resource

RECORD No. 1967/123

GILES- CARNEGIE SEISMIC SURVEY, WESTERN AUSTRALIA 1961- 1962

The information contained in this report has been obtained by the Department of National Development as part of the policy of the Commonwealth Government to assist in the exploration and development of mineral resources. It may not be published in any form or use in a company prospectus or statement without the permission in writing of the Director, Bureau cf Mineral Resources, Geology and Geophysics.

RECORD

No. 19671123

SEISMIC SURVEY, WESTERN AU3TRALIA 1961 -1962

The information contained in this report has been obtained by the Department of National Development as part of the policy of the Commonwealth Government to assist in the exploration and development of mineral resources. It may not be published in any form or use in a company prospectus or statement without the permission in writing of the Director, Bureau of Mineral Resources, Geology and Geophysics.

S~$ii~l~~ IETRODUCTIOM GEOLOGY GM)I)HYSICAL WORK Iif THE SUEVEY A m

OTIm

OBJECTIVES , ,

F'ROGPATT:II~:E,GZl!TE&\L PROGPLhIU,E MTD RESUXTS, 1361 ADDITIONAL C BJECTIVES, 1962

,

'

PROG&\TJIE AMD TLESULTS, 196 2 DISCUSSION OF PJB-JLTS

1 0. 11

.

12.

GEOLOGICBL I l ~ m R ~ l i T I O P T CONCLUSIOBS RTJF~ii~.Tc:ES

8PPEJDIX A.

S t a f f and equipment

APPBJDIX B.

Table o f o p e r a t i o n s

APPEJDIX C.

s o t - h o l e h i l l i n g setistics

55

A ~ P ~ ~ D. T J IT?at ;: er supplies TABU2 1.

57

.

Comparison of t h e s t r a t i g r a p h y of the Gibson Deserl; a n d 'surrounding a r e a s ( D r n ~ ~ M i on ~ G51 /B3-31) l . , c i n g page

TABLE 2.

Lithology and i n t e r p r e t s t i o n of w e l l s d r i l l e d by Hunt O i l Company.

TABLE 3.

V e l o c i t i e s measured by s o n i c l o g i n . Y a s a l g a No. 2 veil

1A.LZE 3 4.

C o r r e l a t i o n of v s l o c i t (Drm/ing Ho G51 /B3-30

n

.

3

2

!7itlz age and type of roclc.

Facing page 37

Plate 1.

Looality asp 8howhg aurfaoe geology and eelsrnio traverses (~~1D3-8) (WlB3-23)

Plate 2.

Bougusr anomalg aonto-

Plate 3.

Contours of depth t o nm,gaetio:basement . .

Plate 4.

Interpretative mss-seutiosr along the seiamio trsverses

.

. .

'

+

(WD3-24) (e1bQ-25)

Plate 5.

Coqxwison of seisndo aad gravity profiles i n the Mount Saanuel Gradty .Lea . - . (~51p3-26)

Plste 6. Plate 7.

Respoase armes for geophoae and shot-hale. m during the survqy . .

Plate 8.

- mrlable-areer

HJdF 19'Tratteree noise testa

-

a used (%1/B3-29)

seetions (c5lP3-10)

Plate 9.

NNIF 19 Traverse noiae . t e s t s

Plate 10.

NMF 19 Traverse shotdole and gee-ne pattern oompsrisons

Plate 11

.

interpretation

(~51/B>22) ((31 lB3-20)

&mt Ehrersrd l%verse shot-hole and geophoae pattern ,

'

comparisons

(G51 D3-21)

-

Plate 12.

Momt Beadell Trsverso expa.nded spread veloai'ty shoot variable-srea aeation (~51/B3-16)

Plate 13.

Mount Beadell Traverse expanded spread 'velooity shoot. . (~52b3-29) interpretation

Plate 14.

Vclooity and time versrrs depth f r o m expanded spread velooity shoot (G52D3-31)

trarav8rsea

Variable-ma seotions from refle&&on Plate 15.

bbmt Charles, 1961

( ~ 5 1BE^ 3)

Plete16.

Mount ~amusl, 1961

( ~ 5/B3-15 1

Plate 17.

NAIF 19, 1961

Plate 19. Plate 20. Plate 21

.

fl

19,

36 shallow hole d i m ~ pattern, ~ ~ d 1962 (~51/B3-11-3)

&unt Beadell, 1961

. .

Mount Beadell, 1962

(G51 /B3-12-1)

.

,

.

.

.

( ~ 5p3-12-2 1 )

n

I I

P l a t e 22.

I'!Iount W e r a r d , 1962

P l a t e 23.

NIF 13MmtBeadeI4 a ~ l d - h m r d

(~51/53-14) :~nd p l o t t e d c r o s s - s e c t i o n ) (G51/~3-27

(I

.

P l a t e 24.

Lase Xeene

SF' 297,

(~51/~3-28)

Time-distance curves and i n t e r g r e t a t i o n of refractionTmverses P l a t e 25.

Mount & v i e s , Giles, Rasrlinson Range., Lake Hopkins, and Sign2ost (~52/~3-59)

P l a t e 26.

Lake Christopher

(~52/~3-7-11

P l a t e 27.

I m g a n a Turn-off

(~52/B3-9-1)

P l a t e 28.

libunt Charles

P l a t e 29.

I~Iount Samuel

P l a t e 30.

~ ~ 19 . F

P l a t e 31

.

P l a t e 32.

n'lount Beadell Lake Keene

(~52/~3-28)

During p a r t s of t h e 1961 and 1962 f i e l d seasons a recoimaissance seismic survey was made along t h e Weapons Research Establishment road from G i l e s 1~1IeteorologicalS t a t i o n t o Carnegie Homestead i n Western Australia. The main i n v e s t i g a t i o n mas d i r e c t e d a t t h e sedimentary s e c t i o n i n t h e trough between t h e Ifusgrave Block i n t h e e a s t and t h e Yilgarn Block i n t h e v e s t . Surface geologicaL i n v e s t i g a t i o n hed shorn a t h i n l a y e r of f l a t - l y i n g Permian, Iiksozoic, and 'Cainozoic rocks blanketing t h e a r e a from t h e Canning Basin i n t h e north t o t h e O f f i c e r Basin i n t h e south and r e s t i n g unconformably on Precambrian rocks at e a s t and west margins. There was evidence t h a t a t h i c k sedimentary s e c t i o n might be present i n t h e a r e a and it was a l s o known t h a t t h i c k Proterozoic sedimentary sequences e x i s t both e a s t and west of t h e area. I n 1962 t h e r e s u l t s of a reconnaissance g r a v i t y survey c a r r i e d out by t h e BhlR showed t h a t t h e main seismic i n v e s t i g a t i o n was being conducted within t h e a r e a of a major g r a v i t y 'loml,the Gibson Gravity Depression; t h e e a s t e r n p a r t of t h e l i n e from Signpost t o Illaunt Beadell c r o s s e s an elongated north-west trending 'low ' , t h e Mount Samuel Gravity Low; t h e western p a r t of t h e l i n e from Mount Everard t o Carnegie Homestead crosses t h e Herbert Gravity Sub-Depression. Since 1962 o t h e r geophysical and g e o l o g i c a l work has been c a r r i e d out i n t h e a r e a by t h e lease-holders culminating i n t h e d r i l l s n g by Hunt O i l Company of Yoma1 :a No. 2 well t o 3250 f e e t . In t h i s reporft t h e r e s u l t s of t h e BTdR seismic survey have been i n t e r p r e t e d i n t h e 1 i g h t . o f t h e more recent information.. ~ a r m!%in rock sequences Refraction v e l o c i t i e s a s s o c i a t e d with h were determined on outcrops t o t h e e a s t of t h e a r e a . The survey mas t h e n continued westward c a r t y i n g out r e f r a c t i o n probes a t abo~at39-mile Tno p r i n c i p a l r e f r a c t o r s mithin t h e sedimentary s e c t i o n intervals could be c o r r e l a t e d from probe t o probe. T h e s e were f i r s t l y a v e l o c i t y between 10,000 and 11,000 f t / s , vrhich i s i n t e r p r e t e d as being n e a r t h e t o p of t h e Permian s e c t i o n , and secondly a v e l o c i t y between 16,300 and 17,090 f t / s , which i s i n t e r p r e t e d as being n e a r t h e t o p of t h e Proterozoic s e c t i o n ,

.

Short r e f l e c t i o n t r z v e r s e s were recorded over most of t h e r e f r a c t i o n probes west of Signpost t o t e s t t h e e f f e c t i v e n e s s of t h e r e f l e c t i o n method for.mapping s t r u c t u r e i n t h e a r e a and t o a s s i s t i n t h e i n t e r p r e t a t i o n of t h e r e f r a c t i o n probes. The r e f l e c t i o n method mas shown t o be capable of giving usable r e s u l t s on a r e a s of Cretaceous outcrop provided s u f f i c i e n t l y l a r g e numbers of h o l e s and geophones a r e used i n two-dimensional a r r a y s . The maxirmun depth t o t h e 16,300 t o 17,000 f t / s r e f r a c t o r was about 5000 f e e t . It was thought t h a t t h e unknown s e c t i o n at shallower depth might be explained by t h e Lovrer Palaeozoic t o Upper Proterozoic sandstone.mapped at t h e Iragana I n l i e r . In f a c t a r e d sandstone which J i s thought t o be of Upper Proterozoic age was penetrated at t h i s p o s i t i o n i n t h e s e c t i o n by Yowalga No, 2 well.

The amount of seismic evidence obtained showing the depth t o metamorphic basement mas small. A few measurements mere made of a r e f r a c t o r having a velocity of about 20,500 f t / s at depths of 15,000 t o 19,000 f e e t i n t h e Mount Samuel Gravity Low. A f a i r r e f l e c t i o n was obtained from a depth of about 38,000 f e e t i n the Herbert Gravity SubDepression. A t h i c k Proterozoic sedimentary section i s indicated i n both areas. Strong angular unconfonnity was demonstrated by the Yowalga Seismic Survey at Horizon A, which appears t o correlate with the 16,300 t o 17,000 f t / s r e f r a c t o r . Various scattered r e s u l t s of t h e BMR survey, obtained by both r e f l e c t i o n and r e f r a c t ion methods, show t h i s unconformi t y . Possible d i a p i r i c o r dec~llement-typefolds a r e postulated as being crossed by the BMR l i n e j u s t west. of b u n t Charles, between Mount Samuel and NW 19, and at Lake Kaene

.

@

.

rn

*

U n t i l recent years t h e Gibson Desert a r e a of Viestern A u s t r a l i a mas r e l a t i v e l y unexplored. The only t r a c k s e n t e r i n g t h e a r e a ( p l a t e 1) were t h o s e from Alice Springs v i a Blackstone Camp t o Warburton l i s s i o n and from Leonora t o 'Jarburton 1,'Iission; a road from Wilma stopped a t Carnegie Homestead on t h e western margin of t h e a r e a ; t h e Canning ESxploration h a s now forged Stock Route passed on t h e north-west. ahead, g e t t i n g i t s impetus from two sources: t h e i n c l u s i o n of t h e a r e a i n t h e f i r i n g range f o r t h e VJeapons Research Establishment (w.R.E.); and t h e search f o r o i l .

-

I n 1958, a survey p a r t y from W.R.E. and t h e Division of National lhpping made a ground reconn" issance from Signpost, n e a r Warburton lrl;ission, t o Carnegie Homestead ( ~ o h n s o n ,1958) and, i n 1959 t o 1960, a d i r t road was constructed by W.R.E. along t h e l i n e of t h a t reconnaissanc?. P r i o r t o t h i s , W.R.E. had e s t a b l i s h e d Giles Weather S t a t i o n and had constructed a road from Giles t o Warbl-q:-t:on i n 1958. Since then o t h e r roads have been constructed by W.R.E. throughout t h e a r e a . A u s e f u l d e s c r i p t i o n of t h e a r e a between Giles and Cariegie i s given by Johnson. It i s i n t e r e s t i n g t o n o t e t h a t more than 4 y e a r s l a t e r t h e wheel-tracks of a Land Rover belonging t o t h e o r i g i n a l recol1naissance p a r t y could be followed f o r 7 miles . south-west from IITLF 23. I n mid 1960, L e s l i e (1 961 ) c a r r i e d out a geological reconna i s s a n c e f o r fiome-Broken H i l l Pty Ltd i n t h e Gibson Desert a r e a ; i n p a r t i c u l a r he c a r r i e d out a reconnaissance along t h e Giles-Camegie road, which r a n c e n t r , - l l y through t h i s a r n a . A t t h e commencement of t h e seismic survey describe$ i n t h i s Record, t h e r e p o r t by L e s l i e was t h e only f a i r l y cougehensive statemeat on t h e geology of t h a t p a r t of t h e Gibson Desert a r e a where t h e p r i n c i p a l seismic i n v e s t i g a t i o n w a s proposed. Since 1960, widespread geologj.ca1 and g e c ~ h y s i c a l surveys have been made i n t h e a r e a (see Chapters 2 and 3 ) . The main part of t h e seismic survey vras made along t h e road from Giles t o Carnegie during p a r t s of t h e 1961 and 1962 f i e l d seasons. Its purpose was t o i n v e s t i g a t e t h e sedimentary s e c t i o n i n t h e trough between t h e t n c a r e a s of Precambrian outcrop, one l y i n g e a s t from Signpost ( t h e lilusgrave lock) and t h e o t h e r n e s t of Carnegie Homestead ( t h e Yilgairn lock).

I .a.

The seismic t r z v e r s e s were l a i d out by t h e s i d e of t h e r!>ad, mhich was well s u i t e d f o r t h e purpose because of i t s very long s t z a i g h t s t r e t c h e s . Several r e f r a c t i o n t r a v e r s e s were extended t o such l e n g t h s k h - , t t b road had t o be l e f t and d i f f i c u l t country mas t r a v e r s e d ; t h e whole of t h e Lake Keene t r a v e r s e l i e s 40 miles off t h e road. The r e s u l t s of t h e survey a r e discussed and i n t e r p r e t e d i n t h e l i g h t of more recent work. Although t h i s has not a f f e c t e d t h e nain conclusions of t h e survey, it h a s enabled t e n t a t i v e i n t e r p r e t a t i o n s t o be made of various r e s u l t s t h a t were previously unexplained.

]!lain cam?s were s e t up, i n 1961, near t h e !.rater bore 11 miles south of Signpost and, i n 1962, h a l f -way between NI.:F 1 9 and Mount Beadell. I n both y e a r s i n i t i a l s u p p l i e s n e r e c a r r i e d from Alice Springs. I n 1961 a d d i t i o n a l s u p p l i e s n e r e obtained from Alice Springs and one a d d i t i o n a l supply run was made t o Leonom. I n 1962 f u r t h e r s u p p l i e s were obtained t h r o u ~ ht h e r a i l h e a d a.:Me&harra 520 miles from camp; s t o r e s and ie 190 n i l e s from c m p p e t r o l a e r e c o l l e c t e d i'ron ~ d i ~ e g Homestead where -6hey a e r e d e l i v e r e d f o r t n i g h t l y by c n i e r f r o r Meekatharm. Water f o r F--th d r i l l i n g and cemp use was obtained mainly from bc--3s e r i l l e d by t h e saismic party. A s h o r t note concerning t h e s e bores i s given i n Appendix I). W h e r "?formation corcerning underground water s u p p l i e s i-n t h e a r e a i s given by Sofoulis (1 962, 1963) and Jackson (1 966b). D e t a i l s of s t a f f , equipment, and operational s t a t i s t i c s a r e given i n Appendixes A , 13, and C.

The h i s t o r y of geological probes i n t o t h e Gibson Desert and r e l a t e d neighbouring a r e a s i s given by Wells (1 963). I n t h e p r e p a r a t i o n s f o r t h e seismic survey t h e f o l l o n i n g m a t e r i a l -'-s consulted: Wells, 1960; Veevers and Wells, 1961 ; VJells, Forman, and Ranf ord, 1961 (noa replaced by Wells, Forman, and Rznford, 1964); L e s l i e , 1961 ; k v i d , 1950; Tectonic Nap of A u s t r a l i a (BI~ZR1960). A g e n e r a l i s e d geological map of t h i s a r e a i s given i n Plate 1 The s t r a t i g r a p h y of t h e a r e a - a s known at present i s s m a r i s e d i n Table 1.

.

Topography, Climate, Vegetation, e t c . L e s l i e (1 961 ) described t h r e e main topogra2hic d i v i s i o n s : 1.

1-brginal a r e a s with e l e v a t i o n s from 1500 t o 2000 f e e t ( r a r e l y up t o 2500 f e e t ) c o n s i s t i n g of d i s s e c t e d h i l l s and ranges accompanied by more mature topography with o r without sand ridges. These correspond t o a r e a s i n which Precambrain rocks a r e exposed.

2.

I G r i d i o n a l bordering zones with s t r o n g l i n e a r o r r e t i c u l a t e sand dunes, low mesas, f l a t - t o p p e d ranges, and breakaway s c a r p s , corresponding t o a r e a s of l a t e Palaeozoic g l a c i a l sediments and J u r a s s i c sandstones. The base of .the sand dune l e v e l occurs a t about 1500 f e e t e l e v a t i o n , m d few of t h e f l a t - t o p p e d h i l l s exceed 100 f e e t abovg t h i s l e v e l .

3.

A c e n t r a l semi-plateau a r e a , g e n e r a l l ~ rf r e e of sand and dunes, corresponding t o a r e a s o f L m e r Cretaceous mudstones and s i l t s t o n e s . ' The p l a t e a u l e v e l occurs at about 1600 f e e t e l e v a t i o n and o v e r l o o ~ ~t hs e bordering sand dune zolies. Flat-topped h i l l s and ranges, most

of 1.vhich a r e adjacent t o t h e Giles-Carnegie road, r i s e t o 150 t o 200 f e e t above t h e general p l a t e a u l e v e l . The Cretaceous sediments v e r e overlain i n T e r t i a r y times by d e p o s i t s of bedded white chalcedony, marly chalcedonic breccia, and sandy s i l i c e o u s ii'mestone ( t r a v e r t i n o u s ) and a r e mantled by a Quaternary covering of r e d brown clayey s o i l s and l a t e r i t e rubble. The climate i s t h a t of a dry inland d e s e r t a r e a with r a i n f a l l y 100% l e s s than 8 inches p e r y e a r and temperatllres ~ ~ n s i s t e n t lexceeding i n t h e summer months, Spinifex covers dost o f t h e l a n d s u r f a c e n i t h sporadic l a r g e a r e a s of nulga (acacia) t h i c k e t , Surface water nay be f o ~ n di n rock holes and claypans following occasional heawj r a i n s . More d e t a i l e d information concernin climate and v e g e t a t i o n i s given by L e s l i e (1 961 ) and Jackson (1 966b I n 1961 a f r e s h water l a k e , Lake Gruska, was found by army surveyors t o have s e v e r a l f e e t of rniater i n it: considerable fauna were ?resent. Towards t h e end of 1962 when members of t h e seismic p a r t y v i s i t e d t h e l a k e it was dry. A t t h e request of t h e F o r e s t n j and Timber Bureau, 1C.F. Fowler c o l l e c t e d samples of f r u i t and leaves from t r e e s growing i n and around t h e lake. These nere mainly eucalypt, acacia, and t i - t r e e

.

Geolom' known p r i o r t o survey The a r e a of i n t e r e s t t o t h e seismic survey i s surrounded by t h e ca.n,nikg Br;in t o t h e n o r t h , t h e Amadeus Basin t o t h e north-east, t h e Musgmve Block t o t h e south-east, t h e O f f i c e r Basin t o t h e south, and t h e Yilgarn Block t o t h e west ( p l a t e 1 )

.

Veevers a d Wells (1 961 ) t r a c e d t h e Canning Basin, from i t s contact n i t h t h e s e a between Derby and Port Hedland(Western ~ u s t r a l i a ) southward a s f a r as t h e northern boundaries of t h e MADLEY, VIAMI, COBB, and RAWLIRSON 1:250,000 map a r e a s . The e a s t e r n and western edges of t h ? b a s i n a r e shown, i n t h i s region, as Precambrain sediments and Precambrian metamorphics , while t h e main basin sediments continue south~;rard,comprisi n g Permian and u n d i f f e r e n t i a t e d Nesozoics a o r o s s an ezst-\vest f r o n t about 250 miles wide. The presence of a prcbable s a l t dome at Woolnough H i l l s ( ~ e e v e r sand Wells, 1959a & b ) , i n t h e north-west of lFJARRI, i n d i c a t e d t h e presence of a t h i c k sedimentary s e c t i o n . To t h e e a s t of t h e survey area i n IIACDO!TALD arld RAYlLINSQN, Wells, Forman, and Ranford (1 964) mapped Proterozoic sediments of aggregate t h i c l n e s s exceeding 20,000 f e e t i n t h e western p a r t of t h e Amadeus Basin; t h e r e m s some doubt at t h a t time a s t o whether t h e upper p a r t of t h e Proterozoic s e r i e s was e a r l y Palaeozoic. On t h e northern and southern m a r g i ~ sof t h e Amadeus Ba.ain, Upper Proterozoic sediments r e s t unconformab:y on o l d e r Precambrian rocks, which a r e regarded as basement. I n t h e western p a r t s of FLC\CDO?ALDand RAVJLINSON, Permian g l a c i a l s u n c ~ n f o r m a b ?o ~ v e r l i e Proterozoic sediments. From t h e i r survey of RAYfiINSON and PIUCDOITALD, Wells, Forman, and Ranford made a b r i e f t r i p between Giles Weather S t a t i o n and Carnegie

Homest ead examining f o s s i l i f erous Ivlesozoic rocks i n t h e area (wells, 1960). Betvreen Mount Charles and 'young Range, s i l t stone and sandstones were found i n outcrop, nhich were thought t o be t h e probable continuation of Cretaceous sediments from the Canning Basin; well preserved marine macrofossils occur a t Mount Samuel. Leslie (1 961) spent 5& months on a ground reconnaissance of t h e area bounded by l a t i t u d e s 2305 and 290s and longitudes 123% and 127.5OE. He mapped Loner Cretaceous sediments of t o t a l thickness about 250 f e e t , which extended south from the Canning Basin and covered most of t h e c e n t r a l p a r t of t h e a r e a surveyed. Tvro unconformable Mesozoic u n i t s , thought t o be of J u r a s s i c age, amounted t o only I n n f e e t i n thickness. Permian g l a c i a l s cropped out mainly i n t h e western and southern p a r t s of t h e a r e a , with a maximum thickness of 750 f e e t qeasured 5 .on t h e r i m s t r u c t u r e of the d i a p i r a t Woolnough H i l l s . Leslie . 8 1 . stated;r$@t # I t 1.p :-thi'b . d i a p i r included Upper Proterozoic rocks i n t h e core. s

Further evidence of a t h i c k sedimentary section had been found by Goodeve (1 961 ) when an aeromagnetic reconnaissance indicated a possible 10,000 f e e t of non-magnetic rocks e a s t of hlount Charles. The Tectonic Map of Australia shows Archaean and Proterozoic rocks cropping out e a s t f r o m south of Mount Charles, and west of Carnegie Home stead.

A t the s t a r t of the seismic sumey, t h e r e f o r e , i t was lnovm:

\

(a)

t h a t a thiclc sediment an^ section mas lilceljr t o e x i s t i n t h e survey a r e a ,

(b)

t h a t t h i c k Troteyozoic sedimentary sequences e x i s t both e a s t and west of t h e survey area, and

(c)

t h a t Permian, ~!Iesozoic,and Cainozoic rocks, mostly f l a t - l y i n g t 9 su3-horizontal and not known t o have a t o t a l thickness g r e a t e r than 1200 f e e t , blanket t h e a r e a from t h e Canning Basin i n t h e north t o t h e Officer Basin i n t h e south and r e s t unconformably on Precambrian rocks at t h e east and nest margins of t h i s area.

.

Very l $ t t l e w a s laown concerning: (a)

s i g n i f i c a n t v a r i a t i o n s i n thiclmess of Permian and Sblesozoic rocks,

(b)

t h e presence of Palaeozoic rocks other than Permian glacials,

(c)

t h e nature of t h e Precambrian floor']of the basin, i . e . whether it was Proterozoic o r Archaean, o r

(d)

t h e t e c t o n i c h i s t o r y of t h e area. .

.

Recent geological knorrledge A.T. PIells of t h e BPDt Geological Branch t r a v e l l e d throughout t h e Gibson Desert a r e a by h e l i c o 2 t e r accompanying t h e r e g i o n a l g r a v i t y survey 'oy t h e Geophysical B m c h i n June and J u l y 1962. A summary of t h e s t r a t i g r a p h y described i n h i s regor: ('#?ells, 1963) i s shown in column 2 of Table 1. From 1960, H u n t O i l Company operated permits t o explore i n an q r e a bourided by l a t i t u d e s 25's and 30°S and by longitudes 1230E and 1 2 9 ' ~ p l u s ICIWGSTO>T, but excluding I.IERBERT. Some ace geological mapping mas done, and i n 1962 and 1963, a photogeologic study was made. Four shallow scout wells nere d r i l l e d i n 1965. Although none of t h i s work was published, t h e r e s u l t s have been described i n r e p o r t s of geophysical surveys ~ m d e rt h e Petroleum Search Subsidy Act and i n t h e well completion .. a l s o subsidised. r e p o r t of Yonalga No. 2 (~aclcson, 1966a), which v&s \

The photogeologic study i s s a i d t o have'deTined nunerous a n t i c l i n a l b e l t s a s wzll as s e v e r a l s t r u c t u r e s d l i c h can possibly be c l a s s i f i e d as d i a p i r i c i n o r i g i n , although it i s l a t e r s t a t e d t h a t s u r f a c e f l e x u r e s are almost t o t a l l y absent and t h a t t h e i n d i c a t i o n of subsurface s t r u c t u r e i s only s l i g h t . . A g e n e r a l i s e d geological map i n t h e w - 1 1 completion r e p o r t f o r Yoraalga No. 2 shows a summary of t h e f i e l d geol ~ g yand photogeology It i s seen t h a t The p r i n c i p a l s t n ~ c t u r a lf e a t u r e s a r e shown i n P l a t e 1 most . a n t i c l j q c a l t r e n d s i n BROriRE!, BETTLEY, YOVJALGA, m d TALBOT a r e north-we st :

.

.-

-

.

Three of t h e scout w e l l s were s i t e d i n t h e a r e a defined by t h e Jount Ssnuel Gravity Low ( p l a t e 2 ) , Browne I?os. 1 and 2 on t h e a x i s n e a r t h e g r a v i t y minimum and Yowalga No. 1 twenty miles south of t h e a x i s on t h e minus 70-milligal contour. & s h of t h e s e w e l l s was s i t e d on t h e c r e s t of an a n t i c l i n e l o c a t e d by snismic t r a v e r s i n g ( s e e Chapter 3). The f o u r t h hole, Lennis ITo. 1 , nas one hundred miles t o t h e south-sou-th-east i n t h e north-nest of L ~ ~ ? and I S i n t h e ceiztre of t h e ITorth Lennis Gravity Depression (~azhawand Jackson, 1765). This -
a

-

.

.

.

I n 1965 a reconnaissance geoiogical survey of t h e Gibrpn Desert and surrounding a r e a s mas made f o r Union O i l Developnent Corpomjcion by l ~ k c kand ' Herrmann (1 765). They s t a t e t h a t 28,000 f e e t of Upper Proterozoic t o Cambrian (?) sedimentary rocks a r e exposed on t h e western margin of t h e G i b ~ o nDesert a r e a within a south-.easterly s t r i k i n g s t r u c t u r a l depression. This depression l i e s between a r e a s of Archa.e,m t o Lower Proterozoic g ~ a n i t e ,metamorpllics, and v o l c a n i c s t o t h e south-west of Lake Carnegie and t o t h e north of Lake Disappointment. Folding i n t h e outcroppi= sediments i s c h a r a c t e r i s e d by t h i n elongated and f a u l t e d a n t i c l i n e s separated by broad synclines. Disharmonic f o l d i n g of -i:lcompetent s h a l e ,

carbonate, and evapol i t e beds r e l a t i v e t o t h e more competent sandstone p suggests a decollement s t y l e of folding. fthck i s evident i n o ~ ~ t c r oand and Herrmann s t a t e t h a t they recognised s i m i l a r decollement-type f o l d s i n t h e AkcDonald-Bloods Range a r e a and i n t h e western end of t h e Amadeus Basin, where gypsum, s h a l e , and carbonate beds from t h e B i t t e r Springs Formation a r e d i s h a m o n i c a l l y folded i n t h e cores of t h e elongated anticlines. Webb (1965) makes t h e following summary remarks concerning s t r u c t u r e s i n t h e neighbouring Amadeus Basin. "Spectacular a n t i c l i n a l s t r u c t u r e s occur i n t h e Amadeus Basin along t r e n d s 60 t o 80 miles long p a r a l l e l i n g t h e b a s i n edges. I n d i v i d u a l closed a n t i c l i n e s range from 10 t o 30 miles i n length. Some a r e deeply breached but some a r e closed i n Ordovician o r younger beds. The s t r u c t u r e s a r e c h a r a c t e r i s e d by g r a v i t y minima and a r e thought t o be due t o movement of salt from Upper Proterozoic sourcesf'. He a l s o s p e c u l a t e s t o t h e e f f e c t t h a t d i a p i r i c s.l;ructures a r e known i n both t h e Amadeus and O f f i c e r Basins and t h a t t h e O f f i c e r Basin might have a h i s t o r y of deformation similar t o t h a t of t h e Amadeus Basin. These s p e c u l a t i o n s a r e i n general agreement with t h e s u r f a c e g e o l o g i c a l s t r u c t u r e mapped i n t h e c e n t r a l a r e a by Hunt O i l Com~anyand i n t h e v e s t by Itlack and Herrmann. I n the a r e a of t h e Mount Samuel Gravity Low t h e y a r e supported by t h e r e s u l t s of t h e Yowalga seismic survey and t h e Lennis-Breaden g r a v i t y surveys (see Chapter 3). The r e s u l t s of t h e Yo~rialga seismic surrey show t h a t f a i r l y s t r o n g f o l d i n g h a s taken place below Horizon A, which i s equivalent t o t h e v o l c a n i c s i n Yomalga No. 2 and t o t h e limestone, s h a l e , and gypsum i n Broime Nos. 1 and 2. Also t h e f o l d e d sedimentary s e c t i o n probably extends 15,000 f e e t o r more below t h i s horizon. The evidence of s a l t movement i n t h e a r e a and t h e form of t h e a s s o c i a t e d l o c a l g r a v i t y anomalies supgort t h e t h e o r y t h a t t h i s f o l d i n g was a s s o c i a t e d with salt movement. Both decollement and d i a p i r i c - t y p e f o l d i n g a r e probably p r e s e n t . Folding i s p a ~ a l l e lt o t h e a x i s of t h e trough a s s o c i a t e d with t h e 1,Iount Samuel Gravity Lorn. Subsequent t o t h e major f o l d i n g , erosion has taken place, a v o l c a n i c l a y e r has been formed on t h e eroded surface, and about a thousand f e e t of r e d sandstone h a s been deposited, probably a l l w i t h i n t h e P r o t e r o z o i c e r a . It seems p o s s i b l e that t h e limestone, s h a l e , and gypsum encountered i n Browne Nos, 1 and 2 and t h e anhydrite and gypsum encountered below t h e volcanics i n Yomalga No. 2 may have a common source. The r e d sandstone and t h e v o l c a n i c s encountered i n Yowalga No.2 m y be missing i n t h e Browne wella'through l a c k of deposition o r erosion. Folding appears t o have continued a f t e r t h e major erosion and i s r e f l e c t e d i n t h e s u r f a c e t r e n d s mapped by photogeology; however, t h e s e s u r f a c e a n t i c l i n e s could very well be d e p o s i t i o n a l i n o r i g i n . I f t h e volcanic b a s a l t i s t h e time equivalent of t h e B i t t e r Springs Formation of t h e Amadeus Basin ( s e e note i n Table 1 ), it seems t h a t t h e f o l d e d sediments must be o l d e r than t h e B i t t e r Springs Formation.

An up-to-date geological map of Western A u s t r a l i a was published i n 1966 by t h e Geologic.?.?. cli.nre~r of Western A u s t r a l i a . Some map i s sk.,~wnin P l a t e 1, p a r t i c u l a r l y '. . - .' of t h e geology from t h i ~ on t h e western edge of t h e a r e a covered.

-

Jackson (1966b) has nade a comprehensive review of t h e geology of t h e a r e a included i n t h e o i l e x p l o r a t i o n permits operated by Hunt O i l Company. More d e t z i l e d information i s given concerning t h e geological e x p l o r a t i o n c a r r i e d out f o r Hunt O i l Company. This review came t o hand a f t e r t h e present r e p o r t was w r i t t e n .

OTHER GZOPHYSICAL WORK I N THE SURVEY AREA

A map showing contours of depth t o magnetic basement i n t e r y r e t e d from aeromagnetic surveys i n t h e a r e a i s presented i n P l a t e 3. An aeromagnetic survey made by t h e Bureau of Mineral Resources ( ~ o o d e v e , 1 961 ) showed shallow magnetic basement i n a marked narrow anomaly running north-west from Signpost. This anomaly mas i n t e r p r e t e d a s a r i s i n g from 2 s t r u c t u r e which i s shallow n e a r Signpost and v~hich deepens p o s s i b l y t o 10,000 f e e t a s i t extends under t h e sedimentary basin. M h e r i n d i c a t i o n s from t h i s survey were t h a t t h e r e could be a t h i c k n e s s of more t h a n 5000 f e e t of non-magnetic m a t e r i a l west of Iflount Charles t o beyond Ivlount Beadell. During 1961, reconnaissance aeromagnetic l i n e s with 30-mile spacing were flown f o r H u n t O i l Company i n an a r e a bounded approximately by l a t i t u d e s 24OS m d 300s and by longitudes 123OE and l29oE. The r e p o r t 3n t h i s survey h a s not been published, but a map showing t h e i n t e r p r e t e d depth t o basement i s included i n t h e reviem by Jackson (1 966b). A sedimentary t h i c l m e s s i n excess of 12,000 f e e t i s sholm overlying magnetic basenent tnroughout most of t h e a r e a of t h e LennisBreaden g r a v i t y survey ( s e e Chapter 3 ) . A t h i c k n e s s of 18,000 f e e t i s shorm i n t h e a r e a of t h e Yo~valgaNo. 1 and No. 2 w e l l s . During 1965, a band-type aeromagnet i c survey was flown i n t h e Gibson Desert a r e a by Aero Service Ltd f o r Union O i l Development Corporation and Kern County Land Company. The survey consisted of 20,000 l i n e miles of t r a v e r s e and covered RUIJTON, MORRIS, RYAN, I:I[ADJJEY, WARRI, COBB, and HERBERT. It m a s arranged i n bands s i x miles a p a r t , each band c o n s i s t i n g of t h r e e east-west l i n e s at one-mile i n t e r v a l s . A.1 i n t e r p r e t a t i o n by L-pch (1965) shoivs depths t o magnetic basement i n excess of 25,000 f e e t . The g r e a t e s t t h i c k n e s s e s of non-magnetic rocks occur: a western

(1)

A t t h e e a s t e r n edge of RYAN and COBB; extension of t h e Amadeus Basin.

(2)

I n t h e north-east and north-nest of IIIORRIS and RYAN r e s p e c t i v e l y ; a southern extension of t h e Canning Basin.

I n t h e north-vest of t h e survey a r e a , an i s o l a t e d north-nes+ trending b a s i n mostly i n R-LTITON but extending LL~'LO I:TORRIS, ll'lADLIX, and VIAMI i n t h e south-east and i n t o GUlTldTYA on t h e north-west t o e n unknown e x t e n t . This basin coincides with t h e R u n t on Gravity Sub-Depression ( ~ o n s d a l eand F l a v e l l e , 1963) mentioned l a t e r i n Chapter 3. The Woolnoug11 H i l l s S a l t Dome l i e s at t h e south-eastern end of t h i s b a s i n , where t h e depth t o magnetic basement i s about 24,000 f e e t .

(4)

I n t h e north-east of HERBEI1T, a somewhat smaller 'lowl;a n o r t h westerly extension of t h e O f f i c e r Basin.

A map showing Bouguer anomaly contours reduced from g r a v i t y surveys i n t h e a r e a i s presented i n P l a t e 2.

I n mid 1962, a BI:lR p a r t y , using h e l i c o p t e r s , made a r e g i o n a l g r a v i t y survey which included t h e a r e a of t h e seismic survey ( ~ o n s d a l e and F l a v e l l e , 1963). S t a t i o n s ?:{ere on a five-mile g r i d . Preliminary Bouguer anomalies a r e shovln i n P l a t e 2. The nomenclature of g r a v i t y f e a t u r e s as used i n t h i s r e p o r t h a s been taken from Lorsdale and F l a v e l l e . It should be noted t h a t t h e standzrd nonlenclature as used by t h e BIdR h a s now been changed - e .g. s e e Vale, 1965. The road from Giles Weather S t a t i o n t o Carnegie Homestead c r o s s e s two major g r a v i t y 'low' regions, t h e Cobb Gravity Depression and t h e Gibson Gravity Depression. These a r e s e p a r a t e d by a marked g r a v i t y r i d g e running north-west from Signpost, t h e Warri Gravity Ridge, nhich i s more o r l e s s coincident with t h e n a g n e t i c basement r i d g e found by Goodeve (1 961 )

.

f i o m t h e r e s u l t s of t h e g r a v i t y survey it mas found t h a t t h e main BIsR seismic i n v e s t i g a t i o n w a s being c a r r i e d out w i t h i n t h e Gibson Gravity Depression. The f i r s t p a r t of t h e survey, from Signpost t o Mount Beadell, crossed an elongated north-west t r e n d i n g 'low1, Feature No. 6 - t h e llount S m u e l Gravity Low; t h e second p a r t of t h e survey, west from Mount Everard would pass t o t h e south of t h e c e n t r a l 'low' of Feature No. 1 - t h e Herbert Gravity SubDepression. Another msjor lorn f e a t u r e w i t h i n t h e Gibson Gravity Depression i s another elongated north-west t r e n d i n g b a s i n , Feature Xo. 3 t h e Runton Gravity Sub-Depression. This l i e s t o t h e n o r t h , s e p a r a t e d from - t h e Herbert Gravity Sub-Depression by Feature No. 2 t h e Madley Gravity Swell. I n '.he south-easterr? end nf t h i s b a s i n i s a more l o c a l i s e d deeper l l o ~ l which , contains t'ne Nocihough H i l l s S a l t Dome and which h a s been given t h e nor? p a r t i c u u ~ rname of t h e Woolnoxh H i l l s Gravity Low Feature no. 4.

-

-

Between April 1 963 and hkrch 1965, Hunt # O i l Company made a g r m i t y survey covering BROWHE, most of YOVALGA, t h e south-western h a l f of TALBOT, t h e northern h a l v e s of V/l%T\?OODand LENNIS, t h e south-western corners of BEXTLEX and COOPER, and t h e north-western corner of ~AIGDi (~azhawand Jackson, 1965). Two s i z e s of g r i d mere used: 2 x 6 miles (mostly t h a t p a r t north of+l a t i t u d e 27OS), and 4 x 4 miles. Gravity was read every h a l f a t o t a l of 35,265 s t a t ions. mile zfbng each. l i n e

-

No major changes mere m d e t o t h e r e g i o n a l g r a v i t y p i c t u r e i n BROWITE and t h e south-western corner of BENTLEY already surveyed by t h e BMR. However, many neg l o c a l f e a t u r e s were o u t l i n e d and t h e coverage mas extended t o t h e south. The lvlount Samuel Gravity Low extends i n t o t h e north-western corner of TALBOT, The g r a v i t y 'high' i n south-vest BROWNE, F e a t m e No. 5, extends ' t o t h e south. The general low a r e a (bounded by t h e minus 40-mgal contour) between t h i s 'high' and t h e Warri Gravity Ridge widens t o t h e south, where it j o i n s t h e e a s t e r n Officer Basin ( ~ d a s t r aHunting Geophysics Pty Ltd, 1965).

.

Local g r a v i t y anomalies ofmacy-types, ranging i n s i z e from a f e n s q w r e miles t o s e v e r a l hundred syilare miles, a r e s c a t t e r e d throughout t h e a r e a . Certain of t h e anomalies a r e coincident with s u r f a c e s t r u c t u r e , although t h e majority have rio c o r r e l a t i o n with 'xno?-:n f e a t u r e s . Seismic surveys The seismic survey that i s t h e subject of t h i s r e p o r t was t h e f i r s t seismic work t o be done i n t h e a r e a and p r e l i m i n a r y ' r e p o r t s were i s s u e d atso son, 1963; Fowler, 1963). Since then, f o k c seismic surveys have been made f o r Hunt O i l Company within t h e a r e a of t h e Lennis-Breaden g r a v i t y survey. These t h e Babbagoola, 'Clarburton, Yowalga, and L e n n i ~seismic surveys. The Lennis survey was f a r from t h e BTA3 survey and m i l l n s t be mentioned again. Babbagoola seismic survey. This survey was done by Seismograph Services Ltd i n 1963 using t h e ' S l i b r o s e i s ' method endal all and Hartley, 1964). The survey s t a r t e d with a n o i s e t e s t . The s t r o n g e s t family of n o j s e alignments had a v e l o c i t y of about 3200 ft/s. The s u r f a c e waves, having a v e l o c i t y about 1600 f t / s , and t h e a i r wn.ve were a l s o present. Other events had v e l o c i t i e s ranging from 5000 t o 10,000 ft/s. Comparisons were made between i n - l i n e and transposed techniques. Continuing ni t h t h e transposed technique, experiments were made with regard t o s i z e and type of geophone patch, frequency band, and o f f s e t . The values of t h e parameters were v a r i e d during production but were mostly: Line 1 .,

Transposed method

12. 400 geophones i n a patch 600 x 200 f e e t Offset d i s t a n c e 1320 t o 2640 f e e t V i b r a t o r p a t t e r n 396 o r 528 f e e t i r - Line Sneeps p e r t r a c e 20 Sweep frequency 14-40 c/s Number of vi'orators Line

4 9

3

Transposed method 300 geophones i n a patch 600 o r 400 f e e t x 200 f e e t Offset d i s t a n c e 2640 t o 3960 f e e t V i b r a t o r p a t t e r n 396 f e e t i n - l i n e Sweeps p e r t r a c e 10 o r 20 Sweep frequency 14-40 c / s Number of v i b r a t o r s

Line 4 NE

3

10-fold continuous-depth-point

(c.D.P.)

method

40 geophones p e r t r a c e i n 2 l i n e s 400 f e e t long and 20 f e e t a p a r t Offset d i s t a n c e 1386 t o 3894 f e e t V i b r a t o r p a t t e r n 396 f e e t i n l i n e Sveeps p e r t r a c e 10 Smeep frequency 14-40 c/s Number of v i b r a t o r s

3

On Line 1 , an event at 0.5 t o 0.7 second (Horizon A) was f a i r l y continuous along t h e l i n e . Deeper events occurred sporadically. The north-eastern h a l f of Line 4 was completed using t h e 10-fold C.D.P. method. The south-vrestern h a l f mas completed using t h e transposed method. Horizon A was continuous on both p a r t s of t h e t r a v e r s e . The deeper i n f o r n a t i o n i s b e t t e r with t h e transposed method. A s l i g h t l y improved C.D.P. s e c t i o n mas obtained from a 5-fold s t a c k of only t h e f i v e longest o f f s e t samples. Warburton seismic survey. The survey mas done by Geophysical Associates Pty I t d i n 1964 and c o n s i s t e d of both r e f r a c t i o n and r e f l e c t i o n work (Hunt O i l Company, 1965).

-

On r e f r a c t i o n Line hlM, continuous time/distance curves nere recorded i n both d i r e c t i o n s between two shot-points 101 , 480 f e e t a p a r t . The spread was 13,570 f e e t long c o n s i s t i n g of 24 geophone s t a t i o n s (4 geophones p e r s t a t i o n ) 590 f e e t a p a r t n i t h a 3 - s t a t i o n overlap between adjacent spreads. The r e f r a c t o r v e l o c i t i e s derived from t h e curves nere: velocity

*

Depth be1olar 1500 f e e t A.S.L. (feet )

F i r s t breaks were picked out t o a shot-to-geophone d i s t a n c e of 15,000 f e e t . Beyond t h i s d i s t a n c e l a t e r phases mere picked up t o about a second a f t e r t h e presumed f i r s t breaks. I n t h e region vihere V4 was picked, V must have been i n t e r f e r i n g with i t and i n t h e region where V mas p i c ed V4 and V3 must have been i n t e r f e r i n g with it. 5 Reverse coverage mas not obtained on t h e various r e f r a c t o r s and considerable s t r u c t u r e has s i n c e been demonstrated along t h e t r a v e r s e ( ~ J i c k l e b e r r y ,1964). The accuracy of t h e v e l o c i t y and depth determinations l i s t e d above must be doubtful.

I

On Line AA t h e basement r e f r a c t o r (v5) was followed continuously from 'i#arburton htission, where it was j u s t below t h e s u r f a c e , south-westwards on t h e road t o Laverton, where it plunged t o a depth of 20,000 f e e t i n a d i s t a n c e of 20 miles. The i n t e r p r e t a t i o n shows a monocline. The shot-to-geophone d i s t a n c e ranged from 11 80 t o 136,290 f e e t . A t t h e start of t h e r e f l e c t i o n work a n o i s e shoot was recorded .This consisted of one spread of 24 gzophone s t a t i o n s 30 f e e t a p a r t with one group of 8 geophone" i n a bunch at each s t a t i o n . A f u r t h e r noi?'? t e s t was recorded l a t e r i n t h e survey n i t h a geophone s t a t i o n i n t e ~ v a l of 110 f e e t . Ekperinental r e f l e c t i o n s h o t s nere recorded t o compare t h e e f f e c t i v e n e s s of shot-hole p a t t e r n s , geophone p a t t e r n s , and o f f s e t s . The method adopted f o r production r e f l e c t i o n shooting on Lines BB, EE, and FF mas tskip-continuoust ; s h o t s were recorded from 1560 f e e t off each end of a 1560-ft spread. A charge of 50 t o 1101b was used i n a s i n g l e h o l e 50 f e e t deep. Ammonium n i t r a t e / d i e s o l i n e mixture was used wherever possible. The geophone p a t t e r n used was 16 geophones a t 17-ft i n t e r v a l s .

.

On Line BB t h e r e i s r e f l e c t e d energy a t 0.5 t o 0.7 second ( ~ o r i z o nA) but continuity i s poor. Deeper events a r e almost e n t i r e l y absent.

Lin? DD was shot using a 6-fold C.D.P. method. A s p l i t spread w a s used with 220 f e e t betmeen geophone s t a t i o n s and 16 geophones at 17-ft i n t e r v a l s per s t a t i o n . A shot was f i r e d every 440 f e e t with a charge between 30 and 110 l b i n a s i n g l e hole. The 6-fold C.D.P. stack on Line DD gave a continuous event at 0.6 t o 0.7 second over part of t h e t m v e r s e and again there i s no deeper information. Sporadic events a r e continuous over two o r three records but c o n f l i c t i n g dips and lack of character prevent i n t e r p r e t a t i o n . Yowalga seismic survey. This survey was done by Ray Geophysical Division i n 1965 using t h e 'Thumpert method (Mickleberry, 1964). The survey was s t a r t e d with a noise recording. Two strong noise events had v e l o c i t i e s of 3400 and 1600 f t / s . From the noise a n a l y s i s , a patch vas designed using 288 geophones and measuring 575 f e e t i n l i n e n i t h t h e t r a v e r s e by 253 f e e t perpendicular t o it. Comparisons nere made between i n - l i n e and c i r c u l a r , d r o p patterns. The c i r c u l a r p a t t e r n s proved more e f f e c t i v e and bo,th 400-ft diameter overlapped c i r c l e s n i t h 36 drops per c i r c l e and 200-ft diameter tangent c i r c l e s with 24 and 36 drops were used on Line 32B. Both through-the-patch and in-line-extended methods were used with o f f s e t distances ranging from 0 t o 2000 f e e t and from 4000 t o 6000 f e e t respectively. A f u r t h e r s e t of noise analyses mas made using various patch s i z e s , some of which viere s u i t a b l e f o r C.D.P. recording. The six-fold C.D.P. technique gave b e t t e r r e s u l t s and was us'ed f o r t h e r e m i n d e r of t h e survey. A geophone patch 400 f e e t i n l i n e with t h e t r a v e r s e by 200 f e e t perpendicular t o it nas used f o r p r a c t i c a l l y a l l of t h e C.D.P. work. The number of geophones was varied from 72 t o 108. The i n - l i n e method of dropping, using three l i n e s of drops, was adopted a s standard u n t i l , n i t h t h e introduction-of a second weight truck, a change was made t o two l i n e s . 400-ft drop segments nere used through most of t h e a r e a with t h e number of drops per segment ranging from 40 t o 60. The survey consisted of 19 t r a v e r s e s ranging i n length from 8 t o 24 miles. On almost a l l the t r a v e r s e s , the shallow r e f l e c t i o n ( ~ l o r i z o nA) was an outstanding event and occurred a t times from 0.28 A second deeper r e f l e c t i o n t o 1 .07 seconds (1 160 t o 5025 f e e t ) ( ~ o r i z o nB) occurs a t tim?s'oetrveen 0.75 and 1.77 seconds (3375 t o 10,350 f e e t ) ; t h i s reflec- ion i s continuous only sporadically and, a s it i s part of a sequence of r e f l e c t i o n s n i t h conformable dips, it i s doubtful whether t h e same r e f l e c t o r has been mapped throughout t h i s horizon.

.

Similar s t r u c t u r e i s shown by both Horizons A and B, but t h e dips on Horizon B a r e steeper and t h e deeper beds a r e seen t r u n c a t i n g a t t h e unconformity defined by Horizon A; i n p a r t i c u l a r , Horizon B i s truncated i n places. Reflection Horizon A i s e a s i l y recogn:'s!zble on most of t h e Yowalga t r a v e r s e s , f i r s t l y because it i s t h e s t i s n g e s t l u f l e c t i o n

15:

-

and secondly because of t h e stroni'angular unconformity beneath it. Honever, i f t h i s r e f l e c t i o n i s examined more closely, it i s seen t o be a complex event varying i n s t r e n g t h and character throughout t h e area. Deeper r e f l e c t i o n s , some as strong as o r even sCronger than t h e main r e f l e c t i o n , a r e seen t o be continually converging and coalescing with it, o r a l t e r n a t i v e l y diverging from it. The r e f l e c t i o n at Horizon B i s a function of t h e strength of t h e r e f l e c t i o n a t Horizon A. In p a r t i c u l a r , where t h e Horizon-A r e f l e c t i o n becomes neak t h e Horizon-B r e f l e c t i o n becomes strong. This happens a t t h e northern end of Line 325, which i s t h e nearest point of approach t o t h e 1D~'Ili' 19 and Mount Beadell t r a v e r s e s . The Horizon-B r e f l e c t i o n i s seen c l e a r l y as t h e strongest of a m i t e of conformable r e f l e c t i o n s . Reflections t h a t a r e f a i r l y obviously primary occur down t o t h e bottom of t h e 3-second cross-sections throughout most of t h e area. Most of t h e r e f l e c t i o n s seem t o be primary. The deeper r e f l e c t i o n s a r e ' n o t altvays continuous but become stronger sporadically. I n places they a r e present as an almost c o n t i n ~ 7 . 0nave ~ ~ from Horizon A down. This e f f e c t i s present at t h e northern end of Line l7P. Comparison of Hunt seismic surveys. Line BB.of t h e Warburton survey coincides with Line 1 of t h e Babbagoola survey. The 'Vibroseis' s e c t i o n shows more continuity on Horizon A and more deeper information.

-

Line 4 of t h e Babbagoola survey, Line DD of t h e Warburton survey, and Line 535 of t h e Yowalga survey mere run p a r a l l e l t o and close t o one another. The r e f l e c t i o n section obtained by t h e shothole method with six-fold C.D.?. s t a c k on Line DD lacked continuity on Horizon A and deeper information w a s almost e n t i r e l y absent. The 'Thumper' section on Line 535 had been obtained by a six-fold C.D.P. stack. Horizon A i s strong and continuous and much good q u a l i t y deeper information i s present although sporadic. The 'Vibroseis' s e c t i o n has been obtained by t h e transposed method on t h e south-viestern half and by a five-fold C.D.P. stack on t h e north-eastern h a l f of Line 4, The transposed nethod gives a s e c t i o n approximately equal t o t h e 'Thumper' section i n q u a l i t y and i n information present. The f i v e - f o l d C.D.P. stack gives a s e c t i o n which i s equal t o t h e 'Thumper' s e c t i o n at t h e l e v e l of Horizon A but t~ihichlacks deeper infornation. &act comparison of t h e 'Vibroseis' and 'Thumper' s e c t i o n s i s mad2 d i f f i c u l t by t h e f a c t t h a t 5/4 and 3/2 composites have been used on t h e 'Vibroseis' s e c t i o n s and a 2/0 composite on t h e 'Thumper' section. The f a i l u r e of t h e 'Vibroseis' C.D.P. section t o provide deeper information may be t h e f a u l t of t h e v e l o c i t y function used. Dynamic c o r r e c t i o n s f o r t h e 'Thumper' mere determined from t h e r e s u l t s of an expanded-spread velocity shoot on Line 13C. The time/depth curve obtained i s shown i n P l a t e 14. It i s similar t o t h e curve obtained a t Mount Beadell down t o 10,000 f e e t but departs from s i m i l a r i t y below t h i s depth and must surely be i n e r r o r a s it shows an i n t e r v a l v e l o c i t y increasing uniformly t o about 100,000 f t / s at a depth of . 20,000 feet.. . However, t h e dynamic corrections used i n obtaining t h e 1 Thumper ' sect ions mere e f f e c t i v e i n revealing deep information and mere based on a v e l o c i t y d i s t r i b u t i o n considerably d i f f e r e n t from t h e constant 10,000 f t / s assumed f o r t h e 'Vibroseis ' corrections.

.._

Geological d i s c u s s i o n

The sediments deeper t h a n Horizon A have undergone f a i r l y s t r o n g f o l d i n g follo!nled by erosion. The. f o l d i n g has continued t o a l e s s extent subsequent t o t h e erosion, The geological discussion i n Chapter 2 p o i n t s t o t h i s f o l d i n g baing due !to salt movement. This view i s strengthe7-?d by t h e prec,ence of what appears t o be well-developed p i e r c i n g i n one of t h e s e f o l d s . This w i l l be discussed i n g r e a t e r d e t a i l below. .

I n P l a t e 5 t h e depths t o seismic Horizons A and B, as measured on Lines 13C, 15G, i n d 53B, a r e compared with t h e Bouguer g r a v i t y anomaly p r o f i l e s talcen from t h e r e s u l t s of t h e Lennis-Breaden g r a v i t y surveys. The point a t which a surface a n t i c l i n e i n t e r s e c t s Line 13C i s a l s o marked. Lines 13C and l5G i n t e r s e c t vrhat i s probably t h e same a n t i c l i n a l f e a t u r e , which may bn one of seve-ral running p a r a l l e l t o t h e s u r f z c e s t r u c t u r e and t o t h e g r a v i t y g r a i n . Line 53B i n t e r s e c t s a n o t h e r which could be a p a r a l l e l f o l d . The f i r s t of a n t i c l i n a , sb&ture, t h e s e a n t i c l i n e s runs along t h e axis of t h e Mount Samuel Gravity Low. It looks l i k e an i n c l i n e d f o l d s i t h s t e e p e r e a s t e r n limb. A sharp g r a v i t y doublet coincides n i t h t h e f o l d ; t h e maximum occurs over t h e shallow limb and t h e minimum over t h e s t e e p e r limb. Within t h e core of t h i s a n t i c l i n e a l l r e f l e c t i o n s a r e l o s t across a distance of f i v e miles. R e f l e c t i o n s on e i t h e r s i d e of t h e core i n d i c a t e t h a t t h e mall rocks may be upturned t o depths of 20,000 f e e t o r more. Piercing may have taken p l a c e t o a l a r g e e x t e n t i n t h i s f o l d . Brome Nos. 1 and 2 mere d r i l l e d on t h e c r e s t of t h i s a n t i c l i n e and s t r u c k limestone, shale,and gypsum a t about t h e depth of Horizon A. This could be confirmation of t h e d i a p i r i c n a t u r e of t h e f o l d .

An i n c l i n e d d i a p i r i c f o l d n i t h an exposed core at about t h e depth of Horizon A provides a p o s s i b l e explanation of t h e g r a v i t y doublet e f f e c t , p a r t i c u l a r l y i f t h e s h a l l o v ~limb c a r r i e s a cover of dense b a s a l t . Yowalga No. 2 was d r i l l e d on a more gradual and r e g u l a r s t r u c t u r e . There a r e i n d i c a t i o n s of p i e r c i n g n e a r t h e c r e s t of t h e a n t i c l i n e but only t o a s n a l l e x t e n t . Continuous v e l o c i t y l o g i n Yowalga No. 2 well Schlumberger a sonic l o g i n Yowalga No. 2 well. r e s u l t s a r e summarised i n Table 3.

4.

The.:-.'

OBJECTIVE3

It w a s intended t o conduct a reconnaissance seismic survey along a n approximately east-west l i n e from Giles Weather S t a t i o n t o Carnegie Homestead, using r e f l e c t i o n and r e f r a c t i o n techniques with t h e following o b j e c t i v e s :

,

.

TABLE 3 Velocities measured by sonic l o g i n Yowalga No. 2 well

Age

Lithology

Depth ( f e e t ) 25

-

Mesozoic

Laterite, claystone, sandstone, siltstone.

Lower Permian

Sandstone

Upper Proterozoic

Brick red arkosic sandstone

1335

Upper Proterozoic

Basalt

2390

-

Upper Proterozoic

Sandstone and shale with veins and f r a c t u r e f i l l i n g s of anhydrite and gypsum

Upper Proterozoic Upper Proterozoic

Velocity range (ft/s)

310

2390

- 11,000 9000 - 11,000

2775

14,000- 20,000

2775

- 2910

10,500- 15,000

Dolomite with veins and f r a c t u r e f i l l i n g s of anhydrite and gypsum

2910

-

2930

18 000- 23 000

Shale, s i l t s t o n e

2930

-

3246

11,000- 12,000

..

......

.

.

310

- 1335

8000

,

a 4

1.

To d i s t i n g g s h , by c r i t e r i a involving velocity and s t r u c t u r a l indications such a s unconf ormities, between the main sequences of rocks, more p a r t i c u l a r l y Precambrian metamorphic, Upper Proterozoic, Palaeozoic , and Mesozoic,

2.

To delineate regional structures i f moderately deformed sediments mere detected; more particularly t o help determine directional trends of axes, f a u l t s , and regional dips.

3. To t r a c e t h e tectonic h i s t o r y of any a n t i c l i n a l feature discovered; more p a r t i c u l a r l y t o t r a c e ~ e r i o d sof deposition quiescence, movement, and erosion.

4.

To indicate from seismic evidence nhere stratigraphic d r i l l i n g may be carried out t o produce significant information and t o carry out some such d r i l l i n g when t h e t a r g e t was within the c a p a b i l i t i e s of the d r i l l i n g equipment on the seismic party.

5. To carry out r e f l e c t i o n and refraction traverses

following the main rock sequences by seismic techniques.

It was proposed t o record a number of short refraction t r a v e r s e s located or known outcropping formations a t the eastern edge of, and t o the e a s t , o f , the main sedimentary area; t h i s includes the t r a v e r s e a t Signpost and a l l traverses east of there ( p l a t e 1 ). The purpose was t o determine r e f r a c t o r v e l o c i t i e s associated mith known rock sequences as a means of l a t e r identifying main rock sequences within t h e sedimentary section and a t i t s base.

.

The survey would then be continued nest from Signpost carrying out r e f r a c t i o n probes a t about 30-mile infervals. It was hoped t h a t it mould be possible, by correlating r e f r a c t o r v e l o c i t i e s from probe t o probe, t o measure the thickening of the sedimentary section above metamorphic basement and t o distinguish between f h e main sequences withi n t h e sedimentary section ( i e. Proterozoic, Palaeozoic, and lksozoic)

.

.

From liIount Charles westwards, short r e f l e c t i o n traverses would be recorded over each r e f r a c t i o n probe i n order to: (a)

t e s t t h e effectiveness of the r e f l e c t i o n method f o r mapping structure i n the area and

(b)

a s s i s t i n the i n t e r p r e t a t i o n of t h e refraction probes.

These r e f l e c t i o n traverses ~ i o u l dbe extended t o investigate s t r u c t u r e , a s required by the objectives and where practical. Two short r e f r a c t i o n traverses mould be recorded west of Carnegie Homestead t o measure r e f r a c t o r v e l o c i t i e s on h o r n Proterozoic sediments.and on Precambrian metamorphic rocks, so t h a t agreement might be checked mith t h e v e l o c i t i e s measured a t the eastern edge of t h e basin.

It was thought important -to s e e a h e t h e r t h e metamorphic basement rer"ract o r could be followed a c r o s s t h e basin and ~vhetherit could be d i s t i n g u i s h e d from p o s s i b l e high v e l o c i t y r e f r a c t o r s a i t h i n t h e sedimentary sequence so as t o measure t h e t h i c k n e s s of t h e Proterozoic sediments

.

-

It aas intended t o complete t h e survey i n t n o p a r t s firstly westwards as f a r as Mount Beadell i n 1961, and secondly from Ikunt Beadell t o Carnegie i n 1962. 6.

PROGIIAIIQEAND RESULTS, 1 96 1

.

Proposed .programme

During t h e f i r s t p a r t of t h e programe i n 1961, two months mere t o be spent as f o l l o a s : (1)

A t Mount Cavies, S o u t h A u s t r a l i a , while t r a v e l l i n g between Alice Springs and Giles, t o record a r e f r a c t i o n t r a v e r s e on t h e Precambrian rocks (Musgrave Complex)

.

(2)

A t Giles, t o record a r e f r a c t i o n t r a v e r s e on t h e Precambrian rocks.

(3)

A t Giles, t o record a r e f m c t i o n t r a v e r s e on t h e n o r t h s i d e of t h e Ramlinson Range t o determine v e l o c i t i e s a s s o c i a t e d with t h e Upper Proterozoic Dean Q u a r t z i t e .

(4)

I n t h e Giles a r e a , i f access could be gained t o t h e Carnegie Range abot; 60 miles n o r t h of Giles, t o record a r e f r a c t i o n t r a v e r s e on dolomite beds within t h e Upper Proterozoic B i t t e r Springs Formation and on t h e neighbouring Upper Proterozoic rocks.

(5)

A t Lake Christopher, about 60 miles n e s t of G i l e s , where Permian g l a c i a l rocks crop o u t , t o record a r e f m c t i o n t r a v e r s e and so f i n d t h e seismic v e l o c i t y i n t h i s m a t e r i a l , and i n t h e underlying m a t e r i a l . A geological sample was t o be cored from a shot-hole.

(6)

About 60 miles west of Lake Christopher, and n e a r t h e Iragana B i l l s t q - o f f , t o record a r e f r a c t i o n depth . ~ t h e Mesozoic and Permian probe which s ~ o k penetrake rocks and r e a c h ' t h e underlying high-velocity material. A geological sample mas t o be cored from a shot-hole.

(7)

A t Sunday H i l l , t o record a r e f r a c t i o n depth probe t o reach Precambrian metamorphic o r igneous basement beneath t h e Permian and Mesozoic rocks.

(8)

A t a s u i t a b l e l o c a t i o n j u s t v e s t of Signpost, t o determine a r e f r a c t i o n technique t h a t vlould allow t h e P r e c r ~ b r i mmetamorphic basement and, .= p o s s i b l e , t h e Permian t o be followed westward towards Irlount Charles, i n such a may t h a t t h e thickening of sediments above t h e basement could be estimated.

(9)

If Upper Proterozoic rocks could be l o c a t e d j u s t south of Mount Charles, t o c a r r y out a r e f r a c t i o n depth probe. A geological sample was t o be cored n e a r l ~ b u n tCharles.

(10)

A t about e i g h t miles v ~ e s tof l o u n t Samuel, where t h e Permian i s exposed, t o record a r e f l e c t i o n and r e f k c t i o n t r a v e r s e . A geological sample vas t o be cored.

(1 1 )

Near t r i g point NID 19, t o record r e f l e c t i o n and r e f r a c t i o n probes on t h e l k s o z o i c rocks. A geological sample mas t o be cored a t NnlF 19, n e a r t h e contact of Permian and Tksoaoic outcrops.

(12)

A t Mount Beadell (NhlE' 20), t o record r e f l e c t i o n and r e f r a c t i o n probes. According t o known geology ( ~ e s l i e ,1 961 ) t h i s might r e v e a l J u r a s s i c , Permian, and Upper Proterozoic sequences above Precambrian metamorphic basement. A geological sample mas t o be cored.

.

(13)

I f t h e general seismic p i c t u r e vrarranted it, and i f time permitted, t o m k e f u r t h e r probes i n t h e Mount Charles and Mount Beadell a r e a s t o o b t a i n information about r e g i o n a l t r e n d s .

Programme c a r r i e d out and r e s u l t s The programme proposals o u t l i n e d above were c a r r i e d through with v a r i o u s degrees of completeness. (1)

t o (3) The r e f r a c t i o n t r a v e r s e s at Mount &vies, G i l e s , and t h e Rawlinson Range were completed as planned ( p l a t e 25). "

(4)

Reasonably easy access t o Carnegie Range could not be found. This t m v e r s e was t h e r e f o r e l a i d near Lake Hopkins where Upper Proterozoic rocks occur at shallow depth, but i t seems !.ikely t h a t t h e m a t e r i a l i n v e s t i g a t e d (14,000 f t / s ) was Carnegie Formation r a t h e r than dolomite from t h e B i t t e r Springs Formation as planned ( p l a t e 25).

(5)

The r e f r a c t i o n t r a v e r s e at Lake Christopher was completed as planned ( p l a t e 26).

(-6)

The r e f r a c t i o n depth prohe at Iragana B i l l s turn-off mas recorded as planned butthe maximum v e l o c i t y recorded ivas 14,350 f t / s at a maximum shot-to-geophone d i s t a n c e of 17,169 f e e t ( p l a t e 27).

(7)

The r e f r a c t i o n depth probe at Sunday H i l l was abandoned because no s u i t a b l e t r a c k t o Sunday H i l l could be found.

(8)

This proposal was oaly p a r t l y completed. A r e f r a c t o r of velocity 20,500 f t / s was recorded very close t o t h e surface a t Signpost ( p l a t e 25).

(9)

This proposal mas modified i n t h e f i e l d . Upper Proterozoic rocks nere l o t i d e n t i f i e d with c e r t a i n t y just south of Mount Charles so the traverse was placed on t h e t r a c k at Mount Charles it s e l f , The highest velocity measured by t h e r e f r a c t i o n probe mas 17,800 f t / s a t a maximum shot-to-geophowe distance of 9240 f e e t . The r e s u l t s from t h i s prcbe have been included with r e s u l t s of t h e 1962 work i n P l a t a 28. A short r e f l e c t i o n t r a v e r s e v~asrecorded using s i n g l e holes and s i x geophones, 22 f e e t a p a r t , per t r a c e . No r e f l e c t i o n s nere pickable ( p l a t e 15).

(1 0)

The maximwn velocity recorded i n t h e r e f r a c t i o n probe near lbunt Samuel mas 11,140 f t / s a t a maximwn shot-togeophone distance of 13,200 f e e t . The r e s u l t s from t h i s probe have been included with t h e r e s u l t s of t h e 1962 norlc i n ' P l a t e 29, A short r e f l e c t i o n traverse was recorded using s i t g l e holes 2nd s i x geophones, 22 f e e t a p a r t , per t r a c e . No r e f l e c t i o n s mere pickable ( p l a t e 16). The maximum velocity recorded i n t h e r e f r a c t i m probe near TIID 19 was 10,100 f t / s a t a maximum shot-to-geophone distance of 14,520 f e e t . The r e s u l t ? from t h i s probe have been included with t h e r e s u l t s of the 1962 morlc i n P l a t e 30. The shooting mas intended t o give sharp f i r s t breaks but t h e energy i n t n e forward direotion Tias conriderably lower than i n t h e reverse direction, This appears t o be t h e reason why r e f r a c t o r V2 m y be picked i n t h e reverse but not i n t h e forward direction. Although t h e r e i s energy present on t h e record from SP 808, i t would appear t o be a rapidly a t t e n u a t i v event and i s not pickable. A short r e f l e c t i o n traverse vas recorded using s i n g l e holes and s i x geophones, 22 f e e t a p a r t , per t m c e . Some very poor r e f l e c t i o n alignments were obtnixcd ( p l a t e 17).

(12)

A t Mount Beadell, a r e f r a c t i o n velocity of 10,450 f t / s gave way t o a velocity of 17,300 f t / s a t a c r i t i c a l distance of about 16,000 f e e t . The m a x i m shot-togeophone distance used was 19,800 f e e t . The energy fro111the f i r s t of these r e f r a c t o r s a t t e ~ u a t e drapidly, The r e s u l t s from t h i s probe have been included with t h e r e s u l t s of t h e 1962 work i n P l a t e 31 A short r e f l e c t i o n t r a v e r s e was recorded using s i n g l e holes and shallow 9-hole diamond p a t t e r n s with 6 geophones, 22 f e e t a p a r t , per t r a c e . A number of reflect5.on alignments mere recorded down t o 1.5 seconds; a t timmgrea.t;er than t h i s there a r e many regularly spaced ali,,ments whose significance mas not known ( p l a t e

.

(1 3) .-

.

-

This proposal was not attempted.

.

7 ,. ADDITIONAL OliJECTmS 1962. ._

The o b j e c t i v e s as s t a t e d i n Chapter 4 mere, of collrse, t h e o b j e c t i v e s of t h e whole survey; however, t h e 1961 survey h-d posed c e r t a i n d e t a i l e d problems at IVIount Beadell and e a s t of t h e r e . The a t t i t u d e s of t h e 10,000 t o 11,000 f t / s r e f r a c t o r at Mount Samuel and NiMF 1 9 i n d i c a t e d t h e p o s s i b l e presence of an a n t i c l i n a l a x i s under Lake Breaden. I n order t o develop a p o s s i b l e s t r a t i g r a p h i c d r i l l i n g l o c a t i o n , i . t was required t o lnow i f a r e l a t i v e l y t h i n s e c t i o n was present and wxether t h i s s e c t i o n was complete o r truncated. An e x p l i c i t o b j e c t i v e of t h e continuation of t h e survey i n 1962 vras therefore: (a)

To seek confirmation of p o s s i b l e s t r u c t u r e between Mount Samuel and NIIIF 19.

The r e s u l t s of t h e r e f l e c t i o n t r a v e r s e s had on t h e vrhole been v e n j poor; t h e exception was a t Mount Beadell, where r e f l e c t i o n q u a l i t y mas s t i l l not good. Only simple techniques h a s been used i n t h e r e f l e c t i o n shooting. The usefulness of t h e r e f l e c t i o n method had not t h e r e f o r e been pro2erly assessed a s a meanL f o r ' d e l i n e a t i n g s t r u c t u r e i n t h e a r e a . A f u r t h e r e x p l i c i t o b j e c t i v e of t h e 1962 survey mas: (b)

To improve :eflection s e c t i o n s at NMF 19 and Mount Beadell. PROGMIclE -4ND RESULTS, 1962.

Proposed programme

A s s - t a t e d i n Chapter 6 t h e programme west t o Mount Beadell mas only p a r t l y completed i n 1 961 ; a l s o , as s t a t ?d i n Chapter 7, a d d i t i o n a l o b j e c t i v e s r e q u i r i x f u r t h e r i n v e s t i g a t i o n h ~ dr e s u l t e d from t h e 1961 survey.

In 1962, i.t was proposed t o spend about out t h e following programme:

3 months carrying

7.

A t NMF 19 t o complete t h e 1961 depth probe making every e f f o r t t o record t h e 20,000 f t / s r e f r a c t o r .

2.

A t Nh'Ii? 1 9 t o make every e f f o r t t o o b t a i n r e f l e c t i o n s . To try t o record a r e f l e c t i o n s e c t i o n over t h e r e f r a c t i o r : probe and, i f any s i g n i f i c a n t dips were confirmed and a p r a c t i c a l : pro,-edure e s t a b l i s h e d , t o continue t h e r e f l e c t i o n t m v e r a e an e x t r a 5 miles updi.p

.

3.

Depending on t h e NMF 1 9 r e s u l t s , t o complete t h e r e f r a c t i o n probe at Mount Samuel a t l e a s t t o t h e 17,000 f t / s r e f r a c t o r and i f p r a c t i c a l t o record a r e f l e c t i o n s e c t i o n over t h e r e f r a c t i o n probe.

4

To a s s e s s t h e above r e s u l t s i n conjunction with g r a v i t y d a t a and t o decide whether recording of t h e 20,000-ft/s r e f r a c t o r at fhunt Samuel and Mount Charles mas warranted.

5

To obtain an improved r e f l e c t i o n s e c t i o n at b u n t Beadell over t h e r e f r a c t i o n probe.

6.

meat of Mount E.:e.rard: t o record a r e f r a c t i o n probe t o f i n d t h e depths and a t t i t u d e s of t h e Permian and t h e Proterozoic sediments m d i f possible a l s o of t h e metamorphic o r igneous basement; t o record 5 miles of r e f l e c t i o n t r a v e r s e ; t o take a 5 t o 10-ft core from t h e bottom of a shot-hole as a geological sample,

7.

To f i n d a t r a c k i n t o Young Range from Mount Everard and t o t a k e a geological core from near NIIF 22.

8. t o 10, A t each of t h r e e l o c a t i o n s , west of NhP 23, ) , west of between NIIIF 25 and NMF 27 (&me ~ a n ~ e and NhW 27, t o c a r r y out programmes similar t o t h a t proposed n e a r Mount h r e r a r d i n item 6.

11

.

West of N~W 29: t o record a r e f r a c t i o n probe t o t e s t f o r Permian sediments, Proterozoic sediments, and Precambrian meta.rno~hic rocks; i f metamorphic base., 1.b . . . . ment :i$deep., . $ b !. . ll?t:.. r ~ a b d .,,miles *5 of r e f l e c t i o n t r a v e r s e ; t o t a k e a core from thelbottom of a shot-hole a s a geological sample.

12.

A l i t t l e west of Carnegie vrhere Proterozoic sediments s h o r l d be shallow o r outcropping: t o record a r e f r a c t i o n probe and t o make a l l reasonable e f f o r t s t o record t h e 20,000 f t / s r e f r a c t o r .

13,

To check t h e Precambrian metamorphic r e f r a c t i o n v e l o c i t y west of Carnegie.

Programme c a r r i e d out and r e s u l t s Items (1) t o ( 5 ) of t h e proposed . . General remarks. programme, a t an'd.east of 11bunt Bead-ell, occupied a l a r g e p a r t of t h e time a v a i l a b l e , with t h e r e s u l t t h a t only a r e l a t i v e l y small amount of work was done mest of Mount Et-erard.

A s h o r t r e f l e c t i o n t r a v e r s e vras recorded on t h e s t r a i g h t road ~~ 23 i n p a r t i a l compliance with Items

running between 1 . b u . t Ekerard and ( 6 ) and (8).

Geological cores mere talcen from deep h o l e s i n t h e Young Range i n compliance with Item ( 7 ) , and n e a r NMJ? 23 i n p a r t i a l compliance with Item (8). m e n t h e r e s u l t s became a v a i l a b l e from t h e 1962 helicopter? g r a v i t y survey ( ~ o n s d a l eand F l a v e l l e , 1963) .it appeared t h a t t h e a r e a vrhere a g r e a t e r t h i c h e s s of sedimentary s e c t i o n could be expected, and

therefore t h e a r e a of g r e a t e r i n t e r e s t from t h e point of view of o i l exploration, was i n the Herbert Gravity Sub-Depression, t o t h e north of the road t o Carnegie Homestead, along which it had been intended t o carry out t h e survey - Items (9) t o (11). It was therefore decided t o s h i f t t h e survey t o t h e north and t o c a r r y out a r e f r a c t i o n traverse i n t h e v i c i n i t y of Lake Keene i n p a r t i a l fulfilment of these items. Items (12) and (13) were not attempted. Surveying. The surveyors were a b l e t o t i e i n t o bench-marks been put i n by a survey party every f i v e miles along t h e road; these from t h e Department of t h e I n t e r i o r i n 1961 f o r the regional gravity survey c a r r i e d out i n 1962. The Lake Keene t r a v e r s e l e v e l s were t i e d i n t o Gravity S t a t i o n 200/1962. Some of the traverses occupied i n 1962 had already been occupied i n 1961; where t h i s w a s so 1320-ft spreads, with 110 f e e t between geophone group centres, were used as i n 1961 (NMF 19, Mount Beadell, and Mount ~ h a r l e s ) New cables f o r 1800-ft spreads, with 150 f e e t between ge~phonq~group centres, were c a r r i e d on the party i n 1962 and, where a new traverse was occupied ( ~ o u n tSamuel, Mount Everard, and Lake ~ e e n e,) 1800-ft spreads were used.

.

I j r i l l i n q . Three d r i l l i n g rigs (one Failing and two careys) were operated, except f o r occasional s h o r t periods when water s c a r c i t y made i t necessary t o s t o p t h e Failing, which did not have a i r d r i l l i n g f a c i l i t i e s . A new Mayhew 1000 r i g , which joined the party .on 20th October, s u f f e r e d various t e e t h i n g troubles and, although running i n of the machine and t h e experience gained with i t were valuable, i t d r i l l e d only 2750 f e e t of shot-hole footage. Any excess d r i l l i n g power was used f o r d r i l l i n g geological care holes, anti two core holes having depths of 2'73 and 431 f e e t were d r i l l e d with t h e Failing. The two Carey r i g s d r i l l e d 86$ of thq$hot-hole footage during t h e survey. On t h e NDllF 19 t r a v e r s e and' on parts of t h e Mount Beadell t r a v e r s e the small gravel near t h e surface tends t o f a l l i n shot-holes d r i l l e d with a i r . Augers were used largely f o r both shallow and deep holes, down t o 150 f e e t . The r e s u l t i n g water economy was very valuable. Occasional t h i n hard bands were encountered. Hard material was encountered sporadically on the surface a t Mount Everard, and t h i s would vary over one shot-hole pattern. l~lostof the shallow holes a t Mount Beadell and Mount Lkerard were d r i l l e d with a i r . D r i l l i n g at Lake Keene w a s almost e n t i r e l y with augers. Weathered layer. The t h r e e r e f l e c t i o n traverses c a r r i e d out during t h e .1,962 survey (NID1 19, Mount Beadell, and Mount ~ v e r a r d ) were s i t u a t e d on areas of Cretaceous outcrop ( L e s l i e ' s t h i r d topographic zone). A s might ha.ve been expected from t h e geology, i . e . T e r t i a r y deposits of bedded white chalcedony, marly chacedonic breccia, and sandy s i l i c e o u s limestone (fravertinous), high v e l o c i t y s t r i n g e r s were encountered within t h e f i r s t 150 f e e t of the surface; correspondingly, occasional hard bands were noticed i n t h e d r i l l i n g .

77

:!hen 7;lsa.l;l erig s!io'is were recorded at P2' 820 and FP 821 on Traverse 1IT:P 19, a ~ L - ~ ' L L C ~ ;:]as O T recorded having a v e l o c i t y of 8000 f t / s at a depth of 20 f e e t . There nas previous evidence of t h e presence of s t r i n g e r s and i t v~llasdecided t o record zn uphole shoot a t SP 821 on a s p e s d of 24 s i n g l e geophones at 20-ft i n t e r v a l s (l~n;%sner,1961 ). The a n ~ . e - f r o n tdiagram obtained i s shorm i n P l a t e 6. Siigh v e l o c i t y l a y e r s a r e i n d i c a t e d a t depths of 20 and 40 f e e t . A study of t h e r e s u l t s of t h e uphole shoot recorded a t SP 812 i n 1961 made i t appear t h a t t h e r e n i g h t be a high v e l o c i t y l a y e r a t a depth of 11 3 f e e t . A I k i s s n e r uphole shoot ?!as recorded a i d t h e xsul'is i n d i c a t e high v e l o c i t y l a y e r s at de?ths of 12 and 110 f e e t ( p l a t e 6 ).

a,

L'leissner uphole shoots were a l s o --ecordec?at. sp a d 805 &ere high v e l o c i t y l a y e r s a r e i n d i c e t e d at 15, 25, and 110 feet and 20, 30, and 70 t o 100 f e e t , r e s p e c t i v e l y ( p l a t e 6 ) . .-

-

Thesr uphole shoots demonstrate tlie e r r a t i c and sporadic n a t u r e of t h e high v e l o c i t y s t r i n g e r s t h a t occur i n t h e weathered l a y e r on Traverse NI'Ll? 19. I n such an a r e a t h e v e l o c i t i e s i n t h e weathering and sub-meathering l a y e r s and t h e depth of t h e i r i n t e r f a c e may only be determined by rphole shooting. The high v e l o c i t y l a y e r at a depth of about 110 f e e t seemed t o c o n s t i t u t e t h e base of t h e weathered l a y e r aid seemed -to be f a i r l y continuous; i t was a l s , t h e source of t h e f i - s t breaks 1:lith a deep shot (about 110 f e e t ) . With t h i s i n mind a deep shot was recor!';ed at every shot-point from SP 805 t o 9P 821 , where a deep shot liaci not a l r e a d y been recorded. Some of t h e shots nere not s u f f i c i e n t l y deep because of d i f f i c u l t y i n d r i l l i n g deap holes and i n g e t t i n g h o l e s t o remain open. The present weathering c o r r e c t i o n s on Traverse llTt!IF 1 9 have been computed using t h e uphole shoots at S P 805, SP 812 2nd SP 821 a s b a s i s and i n t e r p o l a t i n g by use of d r i l l logs. A t Mount Beadell a deep shot nas recorded z t each of t h e r e f l e c t i o n shot -2oints. The t h i c h e s s of t h e eathe he red l a y e r was computed from an i n t e r p r e t a t i o n of t h e shallov~r e f r a c t o r s ( p l a t e 31 )

.

A t hlount Elverard v e l o c i t i e s of t h e o r d e r of 13,000 f t / s a r e recorded from 6 f e e t belon t h e s u r f a c e correspondi in^ t o hard m a t e r i a l encountered a t t h e surface by t h e d r i l l s ) . h l y one deep shot was recorded at Mount f i e m r d ; t h i s shows an average v e l o c i t y of 3000 f t / s down t o 72 f e e t .

,

An a n a l y s i s of t h e uphole times over a l l t r a v e r s e s shows t h e low v e l o c i t y (3000 f t / s ) s u r f a c e l a y e r i s 100 f e e t t h a t i n generd o r more t h i c k . It r ~ o u l dappear t h a t most s h o t s throughout t h e survey n e r e f i r e d i n t h e weathering. A t SP 805 on Traverse NlD' 19 a t h i c k l a y e r of h i g h v e l o c i t y m a t e r i a l i s seen t o occur below 80 f e e t ( P l a t e 6 ) . It seems l i k e l y t h a t a similar region of high v e l o c i t y mat-aria1 occurs at shallower depth i n t h e c e n t r e of t h e Mount Beadell tr,v e r s e ( p l a t e 31 )

.

In general the,weathering c o r r e c t i o n s a p p l i e d t o t h e v a r i o u s r e f r a c t i o n probes a r e not considered r e l i a b l e . Variations of t h e o r d e r

of 10 n d l l i s e c o n d s occux at t h e mme p o s i t i o n i n t h e a r r i v z l s from d i f f For exam2le an i r r e g u l a r i t y occurs j u s t e a s t of SP . erent refmctors. 310 at Lake Keene corresponding t o an obvious v a r i a t i o n i n s u r f a c e e l e v a t i o n . W e r e t h e v a r i a t i o n was obvious, smoothing was c a r r i e d out p r i o r t o t h e depth computation. Refraction method. I n t h e extensions t o t h e r e f r a c t i o n probes ' IF 19. a t EJF - . Ilount Beadell, Mount Charles, and Itbunt Samuel ( ~ r o ~ o s e d Programme Items 1 , 3, and 4 ) l a r g e s h o t - t ~ - ~ e o ~ h odnies t a n c e s and l a r g e charges were used ( p l a t e s 28, 29, 30, and 31 ). Because of t h e remoteness of t h e a r e a and t h e l i m i t e d time a v z i l a b l e it mas not p r a c t i c a l t o i n c r e a s e t h e shot-to-geoj2hone d i s t a n c e continuously, a s would have been d e s i r a b l e . Only a few s h o t s were recorded i n each'probe and increments of t h e o r d e r of 25,000 f e e t mere made t o t h e shot-to-geophone dsstances. The method was s u f f i c i e n t t o s a t i s f y t h e primary requirements of t h e survey but d i d e n t a i l e x t r a d i f f i c u l t i e s and doubts i n t h e i n t e r p r e t a t i o n s of t h e probes, as m i l l be noted l a t e r . These f o u r r e f r a c t i o n probes were s i t u a t e d l a r g e l y i n scrub c o n s i s t i n g mainly of srnall t r e c s from 10 t o 20 f e e t high. Light winds blew f r e q u e n t l y &--?ing daylight hours and t h e r e s u l t i n g n o i s e background was high. A q u i c t period, f r e e from wind, occurred r e g u l a r l y j u s t a f t e r dawn, and some long d i s t a n c e recordings were made during t h i s period. E l e c t r i c a l storms accompanied by shov~erswere q u i t e frequent and t h e s e prevented t h e transmission of t h e time-break by r a d i o on several o x a s i o n s

.

It should be n o t i c e d t h a t , although t h e r e a r e shot-point numbers common t o fiD:F 1 9 and filount Beadell t r a v e r s e s , t h e shot-points do not coincide.

.

The charge and depth of shot f o r each r e f r z c t i o n recording i s given i n t h e a p p r o p r i a t e p l a t e . Geophex was used f o r a l l s h o t s except t h e f a r t h e s t ones at Ivbunt Beadell, SF 672 and SP 774, where a mixture of M i t r o l i t e and d i e s o l i n e primed with Geophex was used. Magnetic recordings were nade of most shots. recordings s e r e made on f i x e d gain.

I n 1962 a l l

The computation and p r e s e n t a t i o n of t h e r e f r a c t i o n r e s u l t s I n t h e depth p l o t s , t h e rays a r e l a r g e l y as i n Vale and Smith (1 961 ) at t h e s h o t - p o i n t s have been taken t o a depth p r o p o l ~ k o n a lt o t h e shotp o i n t i n t e r c e p t . However, t h e d i v i s i o n of t o t a l i n t e r c e p t between geophone and shot-point i s l a r g e l y a r b i t r a r y , except on some shallow r e f r a c t o r s and a t Lake Keene, where continuous two-way coverage was recorded between 3hot-point and geophone. The average v e l o c i t y of t h e overburden above a p a r t i c u l a r r e f r a c t o r has been taken a s constant over any one probe.

.

HIXI? 1 9 r e f r s c t i o n t r a v e r s e . The r e f r a c t i o n shooting on ' T r a v e r s e NIG' 19 ( P l a t e 30) was s t a r t e d with a shot t o f u r t h e s t geophone d i s t a n c e i n c r e a s e d , from t h e 14,520 f e e t reached i n 1961, t o 36,960 f e e t (SP 792 and SP 834). The r e f r a c t i o n v e l o c i t y measured was about 17,000 f t / s similar t o t h a t obtained i n t h e Mount Beadell r e f r a c t i o n probe i n 1961

.

-

Attempts a e r e made t o record t h e 20,000-ft/s v e l o c i t y a s a f i r s t event by f u r t h e r i n c r e a s i n g t h e shot-t o-geophone d i s t a n c e t o 50,160 f e e t (SP 782 and SP 844) and then t o 77,880 f e e t (SP 762 and SF 864). From t h e shot at FP 864 a s t r o n g second event mas recorded showing a v e l o c i t y g r e a t e r than 20,930 ft/s. It was computed t h a t it would r e q u i r e a shotto-geophone d i s t a n c e of about 150,000 f e e t t o r e c o r d t h i s r e f r a c t o r as a f i r s t event. Because t h i s event was only recorded 'rom one d i r e c t i o n and because of t h e u n c e r t a i n t i e s involved i n t h e i n t e r p r e t a t i o n of second events, it mas decided t o concentrate f u r t h e r e f f o r t t o record t h e 20,000f t / s r e f r a c t o r a t Mount Beadell, where g r a v i t y r e s u l t s i n d i c a t e d t h a t it night be shallower. The r e f r a c t o r V3 i s c h a r a c t e r i s e d by a r r i v a l s having long periods, mostly about 135 milliseconds. The arrivals from t h e more d i s t a n t s h o t s were emergent but e n e r g e t i c . With t h e records from t h e most d i s t a n t sho-ts t h e r e i s some doubt as t o which phase was picked. .. The event recorded from SP 800 with an apparent v e l o c i t y of 20,800 f t / s i s i n t e r f e r e d by a slo~,verevent on t h e n e a r e r t r a c e s . Although t h e r e i s plenty of energy at t h i s d i s t a n c e it gould appear t o be a t t e n u a t e d f a i r l y r a p i d l y , The event shows a period:of 50 milliseconds.

hlount Beadell r e f r a c t i o n t r a v e r s e ( P l a t e 31). The d i s t a n c e from t h e shot t o t h e f u r t h e s t geophone mas i v c ~ e a s e d ,f i r s t l y by 7920 f e e t , from t h e maximum of 19,eOO f e e t (SP 702 a n d ' ~ d . 7 2 4 )used i n 1961 t o 27,720 f e e t (SP 698 and SP 728), t o record V3 as a f i r s t event over t h e whole spread from both d i r e c t i o n s and t o o b t a i n g r e a t e r two-way coverzge on t h e V3 r e f r a c t o r .

It was attempted t o record f'ne 20,000-ft/s r e f r a c t o r by i n c r e a s i n g t h e d i s t a n c e from t h e shot t o t h e f u r t h e s t geophone by 36,960 f e e t t o 64, 680 f e e t (SP 672 and SP 754). V3 was s t i l l recorded as a f i r s t event. Towards t h e end of t h e survey, a f t e r t h e r e f r a c t i o n work a t Jlount Cnarles and Mount Samuel, a f u r t h e r two s h o t s (SP 652 and SP 774) t7ere recorded with a dista;?ce from t h e shot t o t h e f u r t h e s t geophone increased by 26,400 f e e t t o 91,080 f e e t . A h i g h e r v e l o c i t y r e f r a c t o r was recorded. The a r r i v a l s from t h e s e f u r t h e s t s h o t s shoved good energy but were emergent and t h e r e i s a s l i g h t doubt as t o which phase v!as piclced. s u n t Charles r e f r a c t i o n t r a v e r s e ( p l a t e 28). The 20,000-ft/s r e f r a c t o r hz,d not been recorded at klount S e a d e l l from shot-points 672 and 754. It mas thought t h a t t h i s r e f r a c t o r night be recorded more e a s i l y at Itbunt Charles a small amount of shooting. The e a s t e r n d i p on t h e 17,800-ft /s r e f r a c t o r , measured i n 1961 (wat son, 1 963), was s u r p r i s i n g and it was thought t h a t t h e apparent v e l o c i t y of 18,350 f t / s night be a down- dip metamorphic v e l o c i t y . M h e r measurement a t hlount Charles n i g h t remove t h e n e c e s s i t y f o r more shooting at IZount Samuel, where access was d i f f i c u l t . Two s h o t s (SP 1005 and SP 1021 ) a e r e recorded with d i s t a n c e s t o t h e f u r t h e s t geophones equal t o 14,520 f e e t , and two s h o t s (SP 971 and SP 1055) were recorded with d i s t a n c e s t o t h e f u r t h e s t geophones equal t o 63,360 f e e t . Other t h a n tkis, s h o t s mere recorded from 1320 f e e t from both ends L$ each spread f o r near-surface c o n t r o l .

The i n t e r p r e t a t i o n shows a 17,000-ft/s r e f r a c t o r with f a i r l y f l a t east-nest dip-at a depth j u s t l e s s than 2000 f e e t . Between shotp o i n t s 1013 and 1016 t h e r e f r a c t o r v e l o c i t y i n c r e a s e s t o 19,950 f t / s . 1;ount Samuel r e f r a c t i o n t r a v e r s e ( p l a t e 29). A t NMl? 19, t h e western d i p of t h e 10,100 f t / s r e f r a c t o r , as measured i n 1961 , was not confirmed, and d i p s appeared t o be f a i r l y f l a t throughout t h e s e c t i o n . It w a s t h e r e f o r e decided t o limit t h e morlr a t Mount Samuel t o a quick extension of t h e r e f r a c t i o n probe t o measure t h e approximate depth and a t t i t u d e of t h e 17,000 f t / s r e f r a c t o r . &tensions of t h e Jilount Samuel t r a v e r s e i n i t s o r i g i n a l p o s i t i o n would have involved d i f f i c u l t problems of access. A new t r a v e r s e was surveyed, o f f s e t at an angle of 120 46' from t h e 1961 t r a v e r s e , so t h a t shot-points 9OOA and 95511 would be within easy access of t h e road. Shots were recorded from t h e s e two shot-points with a d i s t a n c e from shot t o f u r t h e s t geophone of 61,200 f e e t i n each case. The 1 7,000-ft/s r e f r a c t o r rva i n d i c a t e d as f a i r l y f l a t - l y i n g a t about t h e same depth a s at NTIF 1 9. The only o t h e r s h o t s t o be recorded vrere at t h e c e n t r e and each end of t h e t r ~ ospreads f o r near-surface control. Lake Keene r e f r a c t i o n t r a v e r s e ( p l a t e 32). Access mas gained t o t h e a r e a by leaving t h e road e a s t of Fame Range and d r i v i n g along t h e f o o t of t h e range through open s p i n i f e x and l i g h t scrub; f u r t h e r n o r t h , sand dune country was crossed by following t h e l i n e of t h e dunes i n a north-westerly d i r e c t i o n . The t o t a l d i s t a n c e of t h e t m v e r s e from t h e road was about 40 miles. The layout of t h i s probe was mvch d i f f e r e n t from t h e others. Continuous r ? c o r d i n g was c a r r i e d out over a d i s t a n c e of f o u r 7200-ft spreads. Shots were recorded on each spread from t h e c e n t r e and ends and t h e n every 7200 f e e t o f f both ends t o a maximum shot-to-geophone d i s t a n c e of 43,650 f e e t . The c o n t r o l obtained i n t h e i n t e r p r e t a t i o n was improved considerably, as two-way coverage between shot-point and geophone mas obtained on a l l r e f r a c t o r s . R e f l e c t i o n method. A s s t a t e d i n Chapter 7, an e x p l i c i t o b j e c t i v e of t h e 1962 survey mas t o improve r e f l e c t i o n q u a l i t y at NlbIF 1 9 and Tdount ~ e a d e l l . . It mas Eequired t ~ - ~ teh et b e s t r e s G l t s with t h e equipment a v a i l a b l e . 24 geophones p e r t r a c e was t h e maximum number t h a t could be used f o r a spread of 24 t r a c e s . The nrogramme was s t a r t e d by carrying out a s h o r t noise t e s t .

It mas considered t h a t t h e main question t o be answered by t h e noise t e s t mas whether i t mould be be1 t e r : (1 )

t o i n c r e a s e t h e number of geophones i n l i n e t o obtain g r e a t e r c a n c e l l a t i o n of t h e organised n o i s e along t h e traverse or

(2)

t o extend t h e p a t t e r n at r i g h t angles t o t h e t r a v e r s e so as t o cancel t r a n s v e r s e organised n o i s e .

The c a n c e l l a t i o n of random n o i s e would arrangements, probably more by t h e l a t t e r because average spacing. It mas t o be borne i n mind t h a t c a n c e l l a t i o n of l o n g i t u d i n a l organised n o i s e (and be obtained by subsequent mixing o r compositing.

be increased by both of t h e increased an increased random n o i s e ) could

I n a noise t e s t reoorded n i t h s i r g l e geophones, n o i s e i s recorded at l a r g e amplitude which would be reduced considerably by t h e b a s i c i n - l i n e geophone group ( s i x geophones, 22 f e e t a p a r t ) which had been used i n 1961. It mas considered t h a t t h e irformation r e q u i r e d f o r t h e s o l u t i o n of t h e problem as s t a t e d above was nhat n o i s e remained a f t e r t h e a p p l i c a t i o n of f i l t e r i n g by t h e b a s i c group. It was t h e r e f o r e decided t o c a r r y out a n o i s e t e s t recording with t h e b a s i c group. Noise Test at SP 81 3 on Traverse NhP 19. The layout used i n t h e n o i s e t e s t i s shown i n P l a t e 8. Shallow ( 1 5 - f t ) and deep (85-ft ) s h o t s were recorded on a l l t h r e e l o n g i t u d i n a l spreads a i d both cross-spreads. A l l s h o t s n e r e recorded using A.G.C. and f i l t e r s e t t i n g s a s f o r a r e f l e c t i o n record. The r e s u l t s of t h e n o i s e t e s t a r e shorn i n v a r i a b l e - a r e a cross-section form i n P l a t e 8. Noise t r a i n s have been picked on t h e s e s e c t i o n s , and apparent v e l o c i t i e s and average periods nere measured. The ~iave-numbervalues corresponding t o t h e mean s p e c t r a l frequency of each wave t r a i n was t h e n computed. The n o i s e t r a i n s have been p l o t t e d i n P l a t e 9 with t h e above parameters marked. Shot-hole and geophone p a t t e r n comparisons on Traverse I'I'IJTF 19. The n o i s e t e s t showed t h a t considerable organised t r a n s v e r s e noise was present. . On the b a s i s of t h e n o i s e t e s t ii n a s decided t o compare 24 geophones i n a square p a t t e r n a g a i n s t t h e b a s i c geophone group i n twin p a r a l l e l spreads between SF 814 and SP 815. Traces 1 t o 12 had 6 geophones p e r t r m e and t r a c e s 13 t o 24 had 24 geo2hones p e r t r a c e . The following shot-hole p a t t e r n s were recorded on t h e comparison spreaQ ( s e e Plate 10)

,-

t,

(a)

Diamond p a t t e r n of 36 shallow h o l e s

(b)

I n - l i n e p a t t e r n of

7 deep h o l e s

(c)

I n - l i n e p a t t e r n of

3

deep h o l e s

The f i r s t two p a t t e r n s mere chosen as being approximately equal and of maximum e f f o r t . I n f a c t t h e 7 dee? h o l e s took longer t o d r i l l t h a n t h e 36 shallow h o l e s . The r e s u l t s of t h e com2arison spread shcved t h a t an imyrovement i n signal-to-noise r a t i o was obtained by going from t h e s i x t o t h e 24 geophone 2 a t t e r n and t h a t a f u r t h e r improvement was obtained by mixing. It mas t h e r e f o r e decided t o continue t h e use of t h e 24 geophone square pattern. The 36-hole diamond p a t t e r n gave only a poor q u a l i t y record and t h e r e f o r e a smaller diamond p a t t e r n was not t r i e d .

The 36-hole diamond p a t t e r n and t h e 7-hole i n - l i n e p a t t e r n gzve records of comparable q u a l i t y but d i f f e r e n t c h a r a c t e r .

...

R e f l_ e-.c t i o n Traverse _.__-. _..,._.. . .-. .-NI\F -12. I n order t o decide between t h e 4 6 - h o l e diamond pat t e n and t h e 7-hole. *-line p a t t e r n , both were used i n recording along t n o miles of traverse."'The r e s u l t s of t h i s recording a r e shown i n P l a t e s 1 8 and 19. The 36-hole p a t t e r n gave t h e more cont inuoui r e f l e c t ions. Because of t h e slowness of t h e method evolved, t h e rei'lection programme at 1Q.P 1 9 w a s c u r t a i l e d and only t h e 2 miles of r e f l e c t i o n t r a v e r s e was recorded. R e f l e c t i o n s were picked on t h e recordings from both t h e 36h o l e and t h e 7-hole p a t t e r n s and a r e p l o t t e d in P l a t e 23. Shot-hole and geo&qe p a t t e r n comparisons on Itbunt Ebemrd Traverse. A s h o r t t e s t of t h e effectivp-less of t h e r e f l e c t i o n method rnrasmade on t h e Mount Eberstrd Traverse a t SP 61 3. The square p a t t e r n of 24 geophones was compared a g a i n s t +Ye b a s i c group of 6 geophones i n twin p a r a l l e l spreads between SP 61 2 and SP 613. A s i n g l e deep shot and a 36-hole diamond pa-ttern of shallow s h o t s were recorded on t h i s comL?arison spread. Tho res1ilts df- .the comparison recordings a r e shonn i n v a r i a b l e a r e a c r o s s - s e c t i o p form i n P l a t e 11

.

.

fiIount Eherard Ee f l e c t i o n Traverse The improvement i n r e cord q u a l i t y obtained from t h e 24 geophone group i n t h e comparison recordings was thought s u f f i c i e n t t o warrant i t s use on t h i s t r a v e r s e . The 36 shallow h o l e s i n a diamond p a t t e r n gave a record q u a l i t y comparable t o t h a t at Nl\F 19. The method t h a t had given t h e b e s t r e s u l t s on t h e NlF 19 t r a v e r s e was t h e r e f o r e used t o record a s h o r t s e c t i o n on t h e Mount Evernrd t r a v e r s e . The r e s u l t s a r e presented i n v a r i a b l e - a r e a crosss e c t i o n form i n P l a t e 22. Reflections were picked and a r e p l o t t e d i n P l a t e 23.

'c

It should be noted t h a t t h e spread l e n g t h used a t Ivbunt Everard was 1800 f e e t as a g a i n s t 1320 f e e t used elsewhere. .. filount Beadell r e f l e c t i o n t r a v e r s e . A s a l r e a d y s t a t e d i n Chapter 8 t h e s u r f a c e geology i n t h e v i c i n i t i e s of t h e NhP 19, Mount Everard, and P~Tount Beadell r e f l e c t i o n t r a v e r s e s i s similar. A t 1.Ioun-I;Beadell it was t h e r e f o r 2 decided t o start s t r a i g h t away using a diamond p a t t e r n of 36 shallow h o l e s and a square p a t t e r n of 24 geophones, which had had a c e r t a i n amount of success a t ~~ 19 and Records from t h e 1961 sv.rvey with v i s i b l e r e f l e c t i o n s IbTount &erard. mould provide a comparison from which improvenent could be gauged. A r e f l e c t i o n s e c t i o n 23 miles long was shot. The r e s u l t s a r e presented i n v a r i a b l e - a r e a cross-section f o m i n P l a t e 21. R e f l e c t i o n s were picked and a r e p l o t t e d i n P l a t e 23.

-

Ecpanded spread velocilqr shoot. The b e s t r e f l e c t i o n s of t h e sumeg were recorded a t S 3 714 071 t h e ? b u n t Seadell t r a v e r s e . These nere good elov.gh t o v a r r a n t an ex:panded sprezd veloci-by shoot. The r e s ~ l l t sof t h i s v e l o c i t y shoo-t a r e 2reseated i n vz.riablea r e a fo-m i n P l a t e 12. It v i l l be seen t h a t t h e layout was such that ref1ectic;ns w ~ ~ i be l d recorded f r o n t h e sene 1320 fee-t of s ~ ~ b s ~ f faocr e ezch 'of t h e f i v e shots. Spread l e n g t h and shot-hole and geopllone a r r a y s n e r e a s used f o r t h e r e f l e c t i o n t s z v e r s e . The nvcimwn shot--to-geoplio~e d i s t m c e vzs 6500 f e e t . The principal. r e f l e c t i o n s a e r e picked and l e t t e ~ e dfrom A t o Time t i e s nere e x c e l l e n t . A t2:x2 p l o t was constructed and i s presented i n P l a t e 13. G.

.

-

R e f l e c t ions obtained at La!ce Keenc Recording a-t Lake ICeene mas c a r r i e d out p r i m a r i l y w i t h t h e i n t e n t i o n of obtaining informatj.on by t h e r e f r a c t i o n method. S i n g l e s h o t s were recorded on spreads 7200 f e e t long. The tr;?ce spacing was 300 f e e t and t h e r e were 4 geophones p e r t r a c e extended at r i g h t 'angles t o t h e l i n e of t h e t r a v e r s e at 22-ft i n t e r v a l s . Shot-to-geophone d i s t a n c e s ranged from 0 t o 50,000 f e e t . Recordings a e r e made v i t h f i x e d gain and f i l - t e r s e i t h e r 0-30IC o r 0-40K. The high-cut f i l t e r was used t o c u t down mind n o i s e . A l l s h o t s were recorded on maglietic t a p e and it nas hoped t h a t r e f l e c t i o n s might be recorded.

-

In f a c t r e f l e c t i o n s recorded from SP 297 and SP 331 a t shot-to-geophone d i s t a n c e s between 15,000 and 44,000 f e e t . The r e s u l t s obtained from SP 297 a r e presented i n variable-area cross-section fo m i n P l a t e 24. Both an ~ m c o r r e c t e dand a dynamically c o r r e c t e d s e c t i o n a r e shovn (see Chapter 9 ) . Core h o l e s . A g e o l o g i c a l core h o l e n s s d r i l l e d about h a l f a Access was mile t o t h e n o r t h of Charles Knob i n t h e Yo~uzg%nge. gained by t r a v e l l i n g t h i r t e e n -j.les nor-tk along a -I;ra.cl
A geol.clgical COT:, ilole nas d r i l l e d beside t h e road a.bov:i; t h r e e m i l n s 80~:bll-i:!~~~t of PD,P 23, F I e hole nas cored from 422 t o 4.31 f e e t 8:g.d :Feet of core nas recovered. I>e~r:liail;>lant s;?ores, lo;md i n .the core by 3. Ir~Vs~riR,i.i~i!:i.c?;Le i;ii:,t t h e rocl: i s t h e time eili-i.:iv;-.l.ent of t h e GxT,~!~ ?orimi;i.oc i n t h e ?i.tzsoy 7?asin ( v ~ L ~ 1963). s, -77

Ref r a c i i o n ,

~ j . ~ f ieaergy c i s attenil.?.ted rapidly i l l t h c 1 3 , 7 0 0 - f - ~ / ~ 11,000-ft/s r c f r a c t o r at IJount Feadell. r e f ~ ? a c t o r,3,Jc; >?T;Zil 1 C) and i.n I-I;a l s o anpea-s :o be a t ' c n ~ m t e df a i r l y %a-piclly on t h e 1 3 , ~ ) 0 0 - f t / s r e f r a c t o r o-t; ?W 19. There i s i n s ~ g f i c i e - n tinformation t c t e l l rnuch about t h e r a t e of a t t e n m J ~ i o ni n .bile 11 ,000-f-b/z r c f r a c t o r at 1 b ~ n . k n ihe

Samuel. These r e f r a c t o r s have been correlated as Permian (see Chapter 10). These indications of t h i n higher velocity l w e r s n i t h i n the Permian section a r e i n agreement with t h e sonic log i n Yomalga No. 2, where a l a y e r 100 f e e t t h i c k at t h e top of t h e Permian section has a velocity of 10,000 f t / s , followed in sequences by 100 f e e t at about 7000ft/s, 100 f e e t at about 10,500 f t / s and 300 f e e t at about 8500ft/s. A t Nomt Charles the f i r s t a r r i v a l s from the two most d i s t a n t shots, SP 971 and SP 1055, consist of two cycles at low amplitude followed by two cycles increased i n amplitude by a f a a t o r of four. A l l phases have t h e same slope. The period of t h e l o v e r anplitude event i s from 50 t o 80 milliseconds and t h e period of t h e large amplitude wave is from 90 t o 100 milliseconds. Arrivals from t h e 17,000-ft/s r e f r a c t o r recorded at s h o r t e r distance, although ccm?lex, have not the same character. Only one r e f r a c t o r has been inter,..sted. A t Mount Samuelthe a r r i v a l s from t h e tmo most d i s t a n t shots, SP 9OOA and SP 955A, a r e similar t o those at Mount Charles i n t h a t they consist of an i n i t i a l two cycles a t low amplitude follorved by two cycles at about four times t h i s amplitude and t h e periods a r e about the same a s at Mount Chsrles. However, t h e l a r g e r amplitude phases have slopes d i f f e r e n t from those of the f i r s t a r r i v a l s and two r e f r a c t o r s have been interpret.?, havlng v e l o c i t i e s of 17,000 f t / s and 18,200 f t / s . A t NMF 19, the f i r s t a r r i v a l s from t h e 16,800-ft/s r e f r a c t o r are mostly emergent and show evidence of more rapid attenuation. The period i s mostly about 135 milliseconds. The a r r i v a l s from SP 782 and SP 834 are complex. A t b u n t Beadell t h e a r r i v a l s from t h e 16,600-ft/s r e f r a c t o r a r e f a i r l y d e f i n i t e except f o r those recorded from SP 754, where t h e energy i s low. Periods range from 60 t o 100 milliseconds. The c l o s e r recordings show some complexity. The 16,600 t o 17,~.00tat/8r e f r a c t i o n appears t o be a r a t h e r complex event. There i s insufi'icieat' informstion on any probe t o show t h e f u l l nature of t h e complexity. It i s h o r n t h a t t h i s refraction .. probably takes place at an angular unconformity and t h a t t h e rocks below t h e i n t e r f a c e contain layers with considerable variation i n velocity (Chapter 10).

A t I(TMIF 19 t h e second event from SP 864, which shows a velocity of approximately 20,500 ft/s, is very strong. The period i s about 130 milliseconds. A t Mount Beadell the f i r s t evenus from t h e two most d i s t a n t shots, SP 652 and SP 774, show a velocity of about 20,500 f t / s and have periods of ebout 140 milliseconds. The events are d e f i n i t e and f a i r l y strong but t h e r e a r e indications of complexity. On t h e record from SP 652 the 20,500-ft/s event appears t o be intesfered by t h e 16,600-ft/s event; t h i s i s not surprising, as t h e shot-togeophone distance must be just g r e a t e r than the c r i t i c a l distance. Reflection IToise t e s t . The noise t e s t described in Chapter 8 consisted of both longitudinal and transverse recordings of both deep and shallow shots ( p l a t e s 8 m d 9). With the deep shots, not a great many line-ups of coherent noise remained on t h e longitudinal noiee t e s t ; presumably these had been f a i r l y well f i l t e r e d by t h e 6-geophone group used i n t h e t e s t . Transverse noise line-ups came through f a i r l y strongly. With t h e shallow shots t h e longitudinal noise line-ups came through much more

s t r o n g l y and so d i d t h e t r a n s v e r s e line-ups. The most obvioue d i f f e r e n c e between t h e records from t h e deep and shallow s h o t s i s t h e lower frequency c h a r a c t e r of t h e records from t h e shallow shots. A f u r t h e r d i f f e r e n c e i s t h a t a wider wave-number sp5ctrum i s apparent i n t h e deeper recordings. This may be because of t h e lower o v e r a l l n o i s e l e v e l s . The histograms p l o t t e d a t t h e bottom of P l a t e 9 shorn both of t h e s e e f f e c t s .

A very n o t i c e a b l e f e a t u r e of t h e t r a r c v e r s e recordings i s These t h a t most of t h e events have a p p r o x i m t e l y t h e same ve:ocity. v e l o c i t i e s a r e lorn, mostly between 800 and 1000 f t / s . This v e l o c i t y does not appear on t h e l o n g i t u d i n a l recordings and i s most l i k e l y a r e s u l t a n t apparent v e l o c i t y . The histogram f o r t h e shallow l o n g i t u d i n a l noise recording shov~st h r e e sharp peaks. These correspond t o : (1 )I

F i r s t a r r i v a l s and events throughout t h e record with v e l o c i t i e s from 5000 t o 10,000 f t / s .

(2)

Surface waves spreading from t h e shot with v e l o c i t i e s of 1720 and 1900 f t / s .

(3)

A i r waves with v e l o c i t y 1130 f t / s .

3ecause of t h e smaller charges, 2/3 and 2.$ l b as a g a i n s t

5 t o 15 l b , and t h e deeper holes, 1 3 f e e t as a g a i n s t 2 t o 6 f e e t , t h e shallow lioles d i d not blow during t h e r e f l e c t i o n shooting and t h e a i r wave was not obtained. The histogram f o r t h e deep l o n g i t u d i n a l n o i s e recording shows most of t h e n o i s e t o have a wave number below 6 p e r 1000 f e e t . Apparent v e l o c i t i e s range from 4900 t o 23,600 f t / s . A s e p a r a t e small peak r e p r e s e n t s t h e r e s i d i ~ eof t h e surface wave line-ups and shows a v e l o c i t y of 2240 f t / s . During t h e Yowalga seismic survey t h e 'Thumper' produced two strong n o i s e events with v e l o c i t i e s of 1600 and 3400 f t / s . S i m i l a r v e l o c i t i e s mere recorded by t h e 'Vibroseis ' during t h e Babbagoola survey on Line 1. The surface wave v e l o c i t y of 1600 f t / s agrees f a i r l y well with t h e 1720-ft/s measured at ITMI? 1 9 with t h e shallow shots. The event showing a v e l o c i t y of 3400 f t / s may be a P wave r e f r a c t e d i n a high v e l o c i t y l a y e r w i t h i n t h e weathering and may have no exact equivalent at NnD' 19, tvhere events i n t h e same p a r t of t h e recording show v e l o c i t i e s of about 8000 f t / s , which i s s i m i l a r t o t h e f i r s t break v e l o c i t y . Geophone and shot-liole p a t t e r n c o m p a r i s s . The comparisons a r e described i n Chapter 8. The main comparisons were made between SP 814 and SP 815 on t r a v e r s e NNlF 19 following t h e n o i s e t e s t ( p l a t e 1 0 ) . These t e s t s sho171 t h e improvement obtained by changing from 6 geophones i n l i n e t o 24 geophones i n a square p a t t e r n . A s might be expected, s i n c e t h e diamond h o l e - p a t t e r n c a n c e l s t r a n s v e r s e n o i s e , t h i s

irnprovement i s i n some cases more marked mith +he i n - l i n e hole patterns ( a t t e n t i o n .is drarrn t o t h e event a t 2.37 seconds). I

An improvement i n r e f l e c t i o n quality is seen t o be obta.ined

by mixing'.

On such a smll s m y l e i t i s d i f f i c u l t t o decide betnreen t h e 36-11ole dianond and t h e 7-hole in-line patterns. The decision i s made l a r t i c v - l a r l y d i f f i c u l t because of the difference i n frequency content i n t'ne records from the deep and shallom shots. However, comparison of t h e sections i n Plates 18 and 19 shows g r e a t e r r e f l e c t ion continuity t o be obtained mith, the diamond pattern except perhaps i n t h e shallower section a t t i m s l e s s than 0.5 s e c ~ n d . The ~ave-number f i l t e r c h a r a c t e r i s t i c s of t h e various patte&$ used a r e shorn i n P l a t e 7. Comparison of these against t h e histog=ma & . P l a t e 9 w i l l give some idea of the effectiveness of the -. patterns .._

.

--.

The sideways e:ctension of the geoyhone pattern nas limited t o some exient by t h e type of jvxqxr available. These had six e n t r i e s a t 22-foot i n t e r v a l s , The transverse response curve was not computed i n f u l l before use, only t h e zeros -were computed. The curve has two It i s now tliowht that four s t r i n g s of r a t h e r unfortunate maxima. geophones a t 22-ft i n t e r v a l s i~ouldhave been f a r b e t t e r than t h e arrangement used. The transverse noise has sufficiently high navenumbers. The comparisons made on t h e Nount Everard t r a v e r s e (plate 11) again show t h e improvement obtained by changing from 6 geophones i n l i n e -to 24 geonhones i n a square pattern. The 36-hole diamond pattern again proved f a i r l y e f f e c t i v e and the single deep hole proved ineffective. The single deep hole had been t r i e d i n case reflections sho~ildprove e a s i e r t o obtain on t h i s traverse and a l s o f o r up-hole purposes. The expanded spread velocity shoot a t Mount Beadell (plate 12) sholvs what line-ups of longitudinal noise remain a f t e r f i l t e r i n g mith t h e shot-hole and geophone patterns used i n the reflection shooting, i . e . a 36-hole diamond pattern and 24 geophones i n a square pattern. The most evident line-ups of residual noise have a velocity of 7000 t o 8000 ft/s . (gave number = 3). The mixed sections demonstrate the removal of t h i s noise by mixi1g. ~ el efc t i o n sections In 1961 no r e f l e c t i o n s could be picked on t h e r e f l e c t i o n sec-bions from BIount Charles, I:bunt Samuel, and NkIF 1 9 ( p l a t e s 15, 1 6 , 17). F a i r r e f l e c t i o n s mere obtained on t h e llount Beadell traverse ( P l a t e 20)

.

I n 1962, by making a large increase i n e f f o r t , f a i r r e f l e c t i o n s were obtained st ~~~ 13 (plate 19). The same method oktained similar q u a l i t y r e f l e c t i o n s at bbunt Everard ( p l a t e 22) and ingrpved t h e r e f l e c t i o n section a t Mount Beadell ( p l a t e 21 ).

P l e n t i f u l r e f l e c t i o n s a r e seen below 0.9 second. !!lost of t h e s e r e f l e c t i o n s have t h e appearance of being primary, e.g. betneen SP 71 1 and SP 714 at Mount Beadell. Occasionally t h i s r e f l e c t e d energy m s t o g e t h e r t o g i v e t h e appearance of an almost continuous wave, e.g. SP 815 at W 19. The i n t e r p r e t a t i o n of t h e expandedspread v e l o c i t y shoot late 13) makes i t appear a s though t h e event at 1.542 seconds might be a multiple, but t h e picking of t h e r e f l e c t i o n on t h e most d i s t a n t t r a c e s i s doubtful because of interference

.

I n 1961, energy was r a t h e r low at Iblount Beadell n i t h a s i ~ g l ec h e r ~ eof 10 l b , 80 f e e t deep, and with 9 x 2; l b , 6 f e e t deep, Tn 1 962, t h e energy over t h e same p a r t of t h e nbunt i n a diamonl pat t e m Beadell t r a v e r s e was su Cficient, with 36 x 2/3 l b , 1 3 f e e t deep, and r e corded n i t h 24 geophoncs i n place of 6. However, energy was s t i l l low at SP 71 5, SP 71 9, an.d SP 720. The energy on t h e c e n t r a l p a r t of t h e NI!W 19 t r a v e r s e was low. A t Mount Everard 36 x 25 lb mas used znd t h e energy was s u f f i c i e n t . Com,oarison with H~mtO i l Company r e f l e c t i o n t r a v e r s e s . A s l F 19, l ~ f o ~ m Beadell, t already noted i n Chapter 8, t h e t r a v e r s e s at I:dd and Iilount Everard \?]ere s i t ~ ~ a t ei nd a r e a s of Cretaceous outcrop. A l l of t h e Hunt O i l Company r e f l e c t i o n t r a v e r s e s i n t h e Babbagoola, Warburton, and Yovralga seismic surveys mere recorded i n similar a r e a s . Both t h e BnEl t r a v e r s e s and t h e Hunt O i l Company Yo~valga survey t r a v e r s e s were f a i r l y widely sc?,tterced i n t h e type a r e a , and i n each case f a i r l y uniform record quality was'obtained. It would t h e r e f o r e appear t h a t although no coi.rudn t r a v e r s e ivas :i.cc;~i-L~ii,g~Ac-za1c c i x ~ a r i s o n si i ~ justified.

-

'

The method which has had t h e most widespread t e s t i n g i n t h e a r e a i s t h e 'Thumper' i n a s i x - f o l d C.D.P. stack. This method has been found t o be successful over most of t h e Yowalga stuvey a r e a i n nmpping Horizon f\ and t o a l e s s e r extent deeper s t r u c t u r e . From t h e l i m i t e d comparison a v a i l a b l e , i n d i c a t i o n s a r e t h a t t h e 'Vi'aroseii"' with an approximately equal e f f o r t choi.i.lrl give zbout an equal q u a l i t y record (see Chapter 3 ) .

-

On t h e I'WWP19, ltlount Beadell, and Nount B ~ e r a r dr e f l e c t i o n t r a v e r s e s a shot-hole technique using l a r g e two-dimensional patterns of geophones and of shallow holes gave records of approximately equal While t h e r e was no outstanding event which q u a l i t y t o t h e 'Thumper'. could be e a s i l y c o r r e l a t e d with EIorszon A, t h e deeper i n f o r m t i o n was b e t t e r than t h e average q u a l i t y obtained by t h e 'Th~mper'; t h e s l i a l l o a e r information was a l s o b e t t e r . It must be assumed t h a t t h e r e f l - e c t i n g conditions at Horizon A i n t h e v i c i n i t y of t h e BMR t r a v e r s e s a r e d i f f e r e n t from t h s e over t h e g r e a t e r p a r t of t h e Yo~valgasurvey a r e a . The 'Thumper' s e c t i o n has c l e a r l y r e s o l v a b l e information t o t h e bottom of t h e 3-second section. Horizon A i s a strong continuous event, u s u a l l y a two and a h a l f cycle pulse with a period from 55 t o 65. milliseconds. Deeper events a r e not everywhere continuous but they a r e s u f f i c i e n t l y so t o show deeper s t r u c t u r e over most of t h e a r e a . The periods of -the r e f l e c t e d events range from 50 t o 70 milliseconds.

The 'Vibroseis ' s e c t i b n probably contains a l l t h e information p r e s e n t i n t h e 'Thumper' s e c t i o n ( s e e Chapter 3) but c o n f l i c t i n g digs on t h e composited s e c t i o n s tend t o destroy t h e reso1.ution. The v i b r a t o r frequency sweep was 14 t o 40 c/s and t h e periods o! most of t h e r e f l e c t e d e v e n t s a r e between 40 and 50 milliseconds. R e f l e c t i o n s with good r e s o l u t i o n and f a i r c o n t i n u i t y occur t o . t h e bottom of t h e 3.6-second s e c t i o n s a t NlD 19, Mount Beadell, and Mount Everard ( p l a t e s 19, 21,and 22). The frequency content of t h e shoth o l e s e c t i o n s depends on t h e depth of h o l e , a s discussed f o r t h e n o i s e t e s t (Chapter 9 ) . However, t h i s e f f e c t i s not so marked f o r r e f l e c t e d The periods of t h e r e f l e c t e d events l i e e v e n t s ( c f p l a t e s 1 8 and 19) mostly i n t h e range 30 t o 40 milliseconds. The r e s o l u t i o n and c h a r a c t e r of e v e n t s i s probably b e t t e r t h m i n t h e s e c t i o n s obtained by t h e surface input methods. I n t h e b e s t q u a l i t y records, f o r i n s t a n c e SP 711 t o SP 714 at P~buntBeadell, t h e r e i s a c e r t a i n amount of i n t e r f e r e n c e i n t h e deeper s e c t i o n between events with s l i g h t l y d i f f e r e n t dips. A c e r t a i n amount of similar i n t e r f e r e n c e i s present on t h e 'Thumper' s e c t i o n s but t h e primary events a r e strong e n o ~ g ht o overcome it i n a long s e c t i o n . However, t h i s i n t e r f e r e n c e may point t o t h e d e s i r a b i l i t y of a C.D.P. method f o r multiple suppression. With a shot-hole method t h i s could talce t h e form of a s i x f o l d C.D.P. s t a c k using a diamond p a t t e r n of nine shallow holes.

.

.

R e f l e c t i o n s obtained at Lake Keene. I n P l a t e 24 t h e strongest r e f l e c t i o n s occur i n a window between r e f r a c t e d events with v e l o c i t i e s Reflections a r e present t o t h e bottom of about 6200 and 9OOO f t / s . of t h e s e c t i o n at 5.7 seconds, but events deeper than t h e strongest r e f l e c t i o n a t something over f o u r seconds a r e very weak and could p o s s i b l y be m u l t i p l e s

.

A t2:x2 p l o t of t h e strongest r e f l e c t i o n g i v e s an apparent v e l o c i t y of 22,400 f t / s and a c e n t r e time of 4.2 seccnds. This v e l o c i t y i s t o o high t o be compatible mith t h e v e l o c i t i e s t h a t have been measured i n t h e a r e a ( s e e Chapter 1 0 ) . It appears t h a t t h e r e f l e c t i n g horizon must dip t o t h e west. To determine dynat.lic c o r r e c t i o n s , t h e i n t e r v a l v e l o c i t y was taken a s 13,600 f t / s t o a d ~ p t hof 4,500 f e e t mith a constant v e l o c i t y of 19,000 f t / s below t h i s . It was found d i f f i c u l t t o produce a 4vnamically c o r r e c t e d s e c t i o n and t h e dynamic c o r r e c t i o n s equivalent t o a c e n t r e time of 4.0 seconds a e r e a p p l i e d as . s t a t i c c o r r e c t i o n s . R e f l e c t i o n alignments a r e a l s o v i s i b l e on records from SF 301 and SF 305. I\!hgnetic recordings from o t h e r shots with t h e necessary . , o f f s e t a r e not of s u f f i c i e n t duration. It i s not known whether t h e method i s of g e n e r a l a p p l i c a t i o n i n mapping deep r e f l e c t o r s i n t h e a r e a . 10.

GEOLOGICAL I N T W m A T I O N

T h i s s e c t i o n i s discussed i n t h e following order: c o r r e l a t i o n of r e f r a c t i o n v e l o c i t i e s ; c o r r e l a t i o n of r e f l e c t i o n s e c t i o n s ; i n d i c a t i o n s of s t r u c t u r e .

TABLE 4 Correlation of v e l o c i t y with age and t m e of rock.

T y p e of rocks

Age of rocks

C o r r e l a t i o n s i n unknown s e c t i o n

Outcrop r e f r a c t i o n probes

Sonic l o g Yonalga No.2 (ft/s)

Locat ion

Traverse

Velocity (ft/s)

Velocity ( f t / s )

bog0

?recar~br$an (undifferentiated)

Upper ?roterozoic

ikiount Davies

Lletamorphic 2nd igneous

Volcanics

- Basalt

s~r6 7

14,000

-

6 7 2

?ZOO

Shale & s i l t s t o n e

3 3 53 11,000 274J

3 r i c k red a r k o s i c sandst one

9,330

-

Sandstone

8,300

15,000

-

Rswlirlson Iiange

16,100 4'107

Lake Christopher

16,010 cssrq

2odiwa (Amadeus 3asin)

18,300

12,000

-

11,000

-

d.

e Hopkins

Sandstone, s i l t s t o n e , claystone and porcellanite

NOTE:

*

5,000

-

57k

14,000 4267 (probably Carnegie orm mat ion)

Lake G e n e

16,053

+g9t

i"2ount Charles

19,950

60

!Jowlt ;armre1

18,290

554

:LS l 9

20,800

Lake Keene

19,320

iliount Charles

17,000

Xount Sanruel

17,300 16,800

IZS

19

3-2

W

*

-

83

11,000

Lake Christopher

11,070 3374 9,OOO

304-f 10,000

Apparent v e l o c i t y measured i n only one d i r e c t i o n .

27+3

6013

19,750 ,'.-- '8

C'

'I'

572 v

.G 40

Mount Bezdell

15,630

Lake Keene

16,350

Y9@d

:fils' 19

11,630

's36

IJoult Samuel

11,COO

3IS3

lZbT 19

1C,000

?"*

11,300

s2S3

3261

3230

Iragana T m - o f f

8,950 2727

ilount i 3 e d e l l

10,700

h u n t iarnuel

8,900

.

Liount Charles

8,800 10,250

rap

2286

7 533

19

1980

Xount 3 e a d e l l

6,500

1-na

6,000

Turn-off

3-7'2 22+3

- 9j($$0 - 8,500 1827

7

6339

3 3 53

10,600

blesozoic

20,500

3 3 53

Lake Keene

tSa4

idount ileadell

62dg

3 657

-

2438

Lower Pecnian

2c,500

7010

13,000 23,000 (~olonite)

10,500

20,590 62*s

*

lC,T 19

6096

5 6

Sandstone & Shale

Signpost

- 20,000

Quartzite

Sinestone % 3olomite

Giles

19,850 18,900 s 76,

26 83,

3'2~

The correlation of refraction v e l o c i t i e s with age and type of rock a s derived below a r e shown i n Table 4. The overall i n t e r p r e t a t i o n i s presented i n cross-section form i n P l a t e 4. The cross-section i s made along the l i n e of the traverses; directions and various surface features a r e indicated, The Bouguer gravity anomaly along the l i n e of the cross. section i s shown f o r comparison. A s already pointed out i n Chapters 3 and 8 the f i r s t p a r t of the survey from Signpost t o Mount Beadell crosses the Mount Samuel Gravity Low and the Lake Keene t r a v e r s e k v e r s e - i s i n the Herbert Gravity Sub-Depression. The intermediate Mount hherard traverse l i e s on the southeastern end of t h e Madley Gravity Swell. Correlation of veloqity with age and type of rock .. A s already mentioned i n Chapter 5 , the refraction probes made a t Signpost and east of there were intended t o produce diagnostic v e l o c i t i e s f o r l a t e r i d e n t i f i c a t i o n of the unknown rock sequences t o the west. These probes had been s i t e d near known outcrops. The v e l o c i t i e s measured a r e tabulated i n column 5 of Table 4 against the age and type of the outcropping rock i n columns 1 and 2. Some v e l o c i t i e s measured i n these probes have been omitted from the t a b l e because of doubt as t o the source rock. However, some other velocity measurements i n known rocks have been included i n column 5.

The 9,500-ft/s r e f r a c t o r a t Lake Christopher has been omitted. It i s within a few f e e t of t h e surface and t h e transmitted energy i s attenuated rapidly. It probably corresponds t o a high velocity s t r i n g e r i q the weathered layer, cf. Chapter 8. .

The 16,010-ft/s -refractor a t Lake Christopher has been included i n column 5 against the Upper Proterozoic Dean Quartzite. Outcrops of t h i s formation occur over an area a few miles east of the traverse. The 14,350-ft/s r e f r a c t o r a t Iragana turn-off has been omitted. The nearest outcrops of Upper Proterozoic or Lower Palaeozoic age a r e a t the Iragana H i l l s . The 14,000-f t/s velocity measured a t Lake Hopkins probably originates i n the Carnegie Formation. Outcrops of the Carne ' e Formation (quartz greywacke, sandstone, s i l t s t o n e , and shale occur a t two miles from the traverse and outcrops of the B i t t e r Springs Formation (dolomite, limestone, c a l c i l u t i t e , and s i l t s t o n e ) occur about f o u r miles from t h e traverse.

f-=

It has been intended t o measure a sample velocity i n the B i t t e r Springs Formation and t h i s may not have been done. I n 1961 i n t h e Amadeus Basin 14 miles north-west of Rodinga, a velocity of 18,900 f t / s was measured i n outcropping limestone beds of the B i t t e r Springs Formation (MOSS,1962). This velocity has been included i n column 5 f o r comparison. The r e f r a c t i o n probe a t Lake Keene i s known t o be i n an area of Permian outcmp and the shallow refraction v e l o c i t i e s measured t h e r e havebeen included i n column 5. The traverses a t Mount Samuel, NMF 19, and Mount Beadell a r e known t o be on areas of Cretaceous outcrop. The near-surface v e l o c i t i e s measured on these traverses by both uphole and r e f r a c t i o n methods have been included i n Column 5 except where such near surface velocity was thought t o be due t o a T e r t i a r y o r weathered layer. The v e l o c i t i e s measured by sonic log i n Hunt Yowalga No. 2 well have been tabulated i n column 3. Where there i s a comparison between columns 3 and 5 f o r the same age and type of rock, t h e outcmp velocity l i e s within the range measured i n the well. A considerable. overlap e x i s t s between the vel'ocities measured by sonic l o g i n the rocks belonging t o the d i f f e r e n t main age groups. Velocities within the Upper Proterozoic sediments a r e a s low as 9000 f t / s and overlap m o s t of the Permian v e l o c i t y range and part of the Mesozoic Range. A s might be expected t h i s is not t r t e t o t h e same extent of the v e l o c i t i e s measured by refraction and shown i n column 5.

Correlation of r e f r a c t i o n v e l o c i t i e s measured i n unknown section west of S i m p o s t The v e l o c i t i e s measured i n the f i v e ref.raction probes from Mount Charles t c Lake Keene a r e tabulated i n column 7 of Table 4 alongside the age and type of rock i n which i t i s thought they originate. The reasons f o r these c o r r e l a t i o n s a r e t o some extent obvious from the Table but w i l l be discussed i n g r e a t e r d e t a i l below.

Jr'..

1

39

-

High v e l o c i t y r e f r a c t o r s (1 8,200 f t / s and pester). The known rocks i n bordering a r e a s v ~ i t hwhich v e l o c i t i e s of 18,200 f t / s o r g r e a t e r may be a s s o c i a t e d a r e : (a)

metamorphic and igneous rocks of Archaean o r Lover P r o t e r o z o i c age,

(b)

limestone and dolomite members of t h e Upper Proterozoic B i t t e r Springs and Boord Formations,

(c)

Upper Proterozoic volcanics.

The v e l o c i t y ranges overlap and no s e p a r a t i o n i s p o s s i b l e on t h e b a s i s of v e l o c i t y alone. The r e f r a c t o r v e l o c i t y of 20,500 f t / s recorded n e a r t h e s u r f a c e on t h e Signpost t r z v e r s e i s c o r r e l a t e d v i t h u n d i f f e r e n t i a t e d Precam5rian metamorphic rocks which outcrop w i t h i n 5 miles both e a s t and south of t h e t r a v e r s e . The v e l o c i t y i s c l o s e enough t o those measured a t Mount Davies and Giles. A l a r g e a r e a of g r a n i t e and a n o t h e r a r e a containing P r o t e r o z o i c v c l c a n i c s l i e not f a r t o t h e south-east and make o t h e r i n t e r p r e t a t i o n s p o s s i b l e . Other events t h a t may be a s s o c i a t e d with metamorphic basenent were recorded from SP 864 ~t N&IF 1 9 and from SF 652 and SP 774 a t !/bunt Beadell. Although n e i t h e r v e l o c i t y was measured acc-mately they were of t h e r i g h t o r d e r and t h e a s s o c i a t e d rocks a r e very deep. It i s p o s s i b l e t h a t t h e s e v e l o c i t i e s o r i g i n a t e i n deeply bried rocks v i t h i n t h e Upper Proterozoic sedimentary sequence.

It i s thought t h a t o t h e r high r e f r a c t o r v e l o c i t i e s recorded a r e li!:ely t o have had t h e i r o r i g i n i n Upper Proterozoic dolomite and limestone, i n p a r t i c u l a r t h e 18,200 f t / s v e l o c i t y a t ltlount Samuel, t h e 20,800 f t / s v e l o c i t y at NTJl? 19 and t h e 19,120 t o 19,750 f t / s v e l o c i t y at Lake Keene. The reasons f o r t h e s e i n t e r p r e t a t i o n s w i l l be discussed belon.

.

Intermediate v e l o c i t y r e f r a c t o r s (16,000 t o 17,000 f t / s ) The only r e f r a c t i o n v e l o c i t y measured i n an outcropping formation, which cane w i t h i n t h e range 16,000 t o 17,000 f t / s , was that measured i n t h e M Proterozoic Dean Q u a r t z i t e , a formation n e a r t h e base of t h e ~ ~ O VUpper sedimentary s e c t i o n . However, v e l o c i t i e s measured i n Upper Proterozoic sediments s t r a d d l e d t h i s range, v i z . 14,000 f t / s at Lake Hopkins t o 18,900 f t / s at Rodinga. It mas thought t h a t , with increzsed depths of b u r i a l and d i f f e r e n t f a c i e s , v e l o c i t i e s intermediate, somewhat higher, and somewhat l o n e r mould be obtained. The 16,600 t o 17,000 f t / s v e l o c i t y measured on a l l t r a v e r s e s from It'Iotut Charles t o lflount Beadell, because of i t s p e r s i s t e n c e and long period, appeared t o o r i g i n a t e i n a massive r e f r a c t o r . On t h e Mount Beadell t r a v e r s e t h e average v e l o c i t y down t o it had been measured as ayproximately 10,000 f t / s . This a a s thought t o be about what might be expected of a mainly Permian s e c t i o n . It was concluded t h a t t h i r e f r a c t i o n mas t a k i n g p l a c e n e a r t h e t o p of t h e Upper F r o t e r o z o i t section.

\

P va!Caai~

/

?

. P40. : ...

It now seems l i k e l y t h a t t h e r e f r a c t i o n i s a s s o c i a t e d with a c o n t i n u a t i o n of t h e Hmt O i l Company r e f l e c t i o n Horizon A (see below). T h i s horizon was found t o correspond t o t h e t o p of t h e v o l c a n i c s i n Yomalga No. 2 w e l l . The v e l o c i t y of 16,600 t o 17,000 f t / s seems r a t h e r low f o r t h e b a s a l t ; a l s o t h e b a s a l t l a y e r i s about one s i x t h of a wavelength t h i c k and i t i s not 'known how widespread t h e l a y e r i s The v o l c a n i c s do n o t seem t o have been a f e a t u r e of aeromagnettc reconnaissance i n t h e a r e a . A l a r g e - s c a l e angular unconformity occurs at Horizon A and i t appears t h a t t h e v e l o c i t y of 16,600 t o 17,000 f t / s must be a s s o c i a t e d - w i t h t h e o l d e r rocks below it.

.

More t h a n a thousand f e e t of brick-red a r k o s i c sandstone o c c u r r i n g above Horizon A h a s been given a n Upper P r o t e r o z o i c age on l i t h o l o g i c a l grounds. This f o m t i o n has a low v e l o c i t y , comparable with t h e Permian s e c t i o n , an??%orizon A i s t h e i n t e r f a c e a t vhich t h e main i n c r e a s e i n v e l o c i t y occurs.

TNO v e l o c i t i e s w i t h i n t h i s mnge mere measured at Lake Keene a t d i f f e r e n t depths. The shallower refraci'or, having a v e l o c i t y of 16,050 f t / s , i s a h i g h l y a t t e n w t i n g l a y e r . It occurs a t about t h e depth where t h e aeromagnetic i n t e x p:etation (Lynch, 1965) has placed a n e x t r u s i v e l a y e r . It seems l i k z l y t h a t t h i s r e f r z c t i o ? t a k e s place i n a l a y e r of v o l c a n i c rocks. The age of t h e s e rocks -s. very doubtful but they have been t e n t a t i v e l y c o r r e l a t e d with t h e Upper Proterozoic v o l c a n i c s f u r t h e r e a s t . The 16,350 f t / s v e l o c i t y i s measured at a depth g r e a t e r by about a thousand f e e t and t h e r e f r a c t o r appears t o be f a i r l y massive. The i n t e r f a c e might be t h e equivalent of Horizon A f u r t h e r e a s t .

.

T-le Low v e l o c i t y r e f r a c t o r s ( l e s s ,than 12,000 f t / s ) r e f r a c t i o n v e l o c i t i e s measured i r t h e unlmo?ln s e c t i o n west of Signpost .. shon a gap between 16,000 and 11.600-ft/s.. The r e f r a c t i o n v e l o c i t i e s measured i n Permian outcrops range from 8950 t o 11 ,070 f t / s and t h e v e l o c i t i e s messured by s o n i c log i n Permian rocks i n Yov~algaNo. 2 range from 7000 t o 1 1 ,000 f t / s . The r e f r a c t i o n v e l o c i t i e s measured i n Mesozoic outcrops range from 6000 t o 9000 f t / s and t h e v e l o c i t i e s measured by sonic l o g i n hlesozoic rocks i n Yonalga No. 2 range from 5000 t o 10,000 f t / s . There i s considerable o v e r l a p of t h e r e f r a c t i o n v e l o c i t y ranges. However, i t r e q u i r e d more than v e l o c i t y data alone t o i n t e r p r e t r e f r z c t o r s a s Mesozoic o r Permian.

A s a l r e a d y mentioned, t h e sub-weathering v e l o c i t i e s recorded at Llount Samuel, Nl'iE' 19, and Mount Beadell were l i s t e d i n column 5 of

Ta31e 4 as Mesozoic. The next deeper events recorded i n t h e s e probes had v e l o c i t i e s from 10,000 t o 11 , O Q - ~ ~ B a d came from depths of between 500 2nd 1600 f e e t . With t h e a d d i t i o n a l L ~ ~ o w l e dtghea t t h e Mesozoic and Permian sediments a r e f l a t - l y i n g , and t h a t t h e t h i c k e s t Mesozoic s e c t i o n measured a t any one place i s t h e 460 f e e t i n Bromne No. 2 v ~ e l l , t h e s e deeper r e f r a c t o r s mere l i s t e d as Permian ( s e e a l s o Chapter 9 ) . Considerable doubt mas f e l t about a s s i g n i n g an age t o t h e rocks showing v e l o c i t i e s of 8800 and 10,250 f t / s at a depth of 300 f e e t at J~Tount Charles. The v e l o c i t i e s a r e marginal and t h e Mount Samuel probe shows an e a s t e r l y dipping Permian r e f r a c t o r . These v e l o c i t i e s

b

41

were t h e r e f o r e l i s t e d a s Mesozoic.

.

The v e l o c i t y of 11 ,600 f t / s from a depth of about 3000 f e e t

at In1IF19 could be Permian, o r i t c o ~ d dbe some u n h o m Palaeozoic u n i t . Ho%ever, it has been c o r r e l a t e d s i t h t h e Upper Proterozoic Sands-tone encountered i n Yosalga No. 2 a t a depth of 1335 f e e t . This formation gave a sonic l o g v e l o c i t y ranging f r o n 9000 t o 11,000 f t / s . C o r r e l a t i o n of r e ? l e c t ion s e c t i o n s at IriF 19, I~IountBeadell, and Mount Werard

It was noted i n Chapter 3 t h a t , although t h e Hunt O i l Company r e f l e c t i o n Horizon A g i v e s a s t r o n g r e f l e c t i o n throughout most of t h e Yowalga survey a r e a , t h e r e a r e p a r t s of t h e a r e a -%ere - t h e r e f l e c t i o n almost disappears. I n p a r t i c u l a r t h i s happened a t t h e northern end of Line 325, which i s a point of c l o s e s t approach t o t h e TTMl? 19 t r a v e r s e . The Horizon A r e f l e c t i o n time at t h e northern ends of , H u n t O i l Company Lines 12D and 12E i s 0.72 second and increzsing, and a t t h e northern end of Line 325 i s 0.9 second. On t r a v e r s e Ii'IG' 19 t h e s t r o n g e s t r e f l e c t i o n occurs a t about 0.7 second, equivalent t o a depth of about 4300 f e e t . There a r e i n d i c a t i o n s of angular urconformity a t t h i s horj.zon. A 1 1 of t h e s e f a c t o r s favour t h e c o r r e l a t i o n of t h i s r e f l e c t i o n with Horizon A. The N1\1w 19 r e f r a c t i o n probe i n d i c a t e s a 16,800-ft/s x~fbsactarat about this depth. A poor r e f l e c t i o n occurs at about 0.62 second on tile s e c t i o n recorded with t h e 7 deep h o l e p a t t e r n (T'lat e 1 8 ) . This ~ o u l dbe about t h e depth where t h e 11 , 6 0 0 - f t / s r e f r a c t i o n t a k e s place and, i f t h e c o r r e l a t i o n of t h i s r e f r a c t i o n i n t h e previous chapter i s c o r r e c t , would represent t h e t o p of t h e P r o t e r o z o i c section.

-

It i s d i f f i c u l t t o c o r r e l a t e t h e r e f l e c t i o n s e c t i o n recorded on t h e I:lovnt Beadell t r a v e r s e a i t h r e f l e c t i o n s e c t i o n s recorded e l s e w h e r e . In t h e exganded-spread v e l o c i t y shoot centred on SF 714 ( p l a t e 12) r e f l e c - t i o n s a r e seen from between 0.1 m d 0.2 second a l l t h e w a y dov~nt h e s e c t i o n . The s t r o n g e s t event occurs a t about 1 . 3 seconds o r a depth of about 6600 f e e t . The Mount Beadell r e f r a c t i o n probe shows t h e 16,600-ft/s r e f r a c t o r occurring a t .a shallovrer depth of 5500 f e e t . It appears t h a t t h i s nay be an a r e a where t h e Horizon A r e f l e c t i o n i s r e l a t i v e l y weak and t h a t Horizon A should perhaps be c o r r e l a t e d v ~ i t ht h e f a i r r e f l e c t i o n a t 1.15 seconds, which i s at a de$h of about 55,00 f e e t . I n d i c a t i o n s a r e t h a t t h e s e c t i o n above ..2iorizon A Ls f a i r l y f l a t i n t h i s a r e a and t h e good r e f l e c t i o n a t 0.545 second would be a t about t h e r i g h t depth t o c o r r e l a t e a i t h t h e r e f l e c t i o n at 0.62 second at NlbD' 19. This r e f l e c t i o n mould t h e n r e p r e s e n t t h e . . t o p of t h e P r o t e r o z o i c s e c t i o n at Mount Beadell. A c o m ~ a r i s o nof i h e avemge v e l o c i t i e s meas~medi n t h e expanded-spread v e l o c i t y shoot at SF 714 v i t h t h e v e l o c i t i e s measured by sonic l o g i n Yonalga No. 2 favours t h e above c o r r e l a t i o n s . The c o r r e l a l i o n of t h e I~ZountEkerard r e f l e c t i o n s e c t i o n i s again doubtfi,~land t h e r e i s no r e f m c t i o n work f o r compal:ison. The b e s t guess night be t h a t t h e s t r o n g event a t about 0.9 second (4000 f e e t ) would c o r r e l a t e with Horizon A. There i s evidence of a n g u l a r unconformity betneen t h i s r e f l e c t i o n and t h a t immediately below i t .

S t r u c t u r a l i n d i c a t i o n s i n t h e Mount Samuel Gravity Low Vi!!ere t h e BMR seismic t r a v e r s e crosses t h e trough a s s o c i a t e d with t h e Mount Samuel Gravity Low, surface s t r u c t u r e and g r a v i t y f e a t u r e s both deep and shallow t r e n d south-e3st a t about 125 t o 135 degrees.

A t t h e northern end of t h e trough a surface a n t i c l i n e occurs as a c r o s s - s t r u c t u r e t r e n d i n g north-east at about 66 degrees. The Mount Charles t r a v e r s e makes a f a i r l y l a r g e angle with t h e main t r e n d . The Mount Samuel and NME' 19 t r a v e r s e s make successi v e l y s m a l l e r angles. It i s necessary t o remember t h i s when looking at t h e c r o s s - s e c t i o n and Bouguer anomaly p r o f i l e i n P l a t e 4. Although t h e r e a r e only a fern seismic measurements of depth t o metamorphic basement, t h e s e lend support t o t h e hypothesis t h a t t h e r e g i o n a l g r a v i t y f e a t u r e s r e f l e c t t h e configuration of metamorphic basement. The measurements concerned a r e t o t h e 20,500-ft /s r e f r a c t o r at Signpost, 1QiZF 19, and hlount Beadell. This r e f r a c t o r was not recorded at Mount Cnarles lalith a shot-to-geophone d i s t a n c e of 63,360 f e e t n o r at I~lount Samuel l i ~ i t ha shot-to-geophone d i s t a n c e of 61,200 f e e t , so t h a t l a r g e depths of b u r i a l a r e a l s o i n d i c a t e d at these locations. The basement configuration shown i n P l a t e 4 a g r e e s a i t h t h a t i n t e r p r e t e d from t h e Bouguer g r a v i t y anomaly on t h e assumption t h a t t h e anomaly i s produced s o l e l y by t h e c o n t r a s t between low density sediments and h i g h e r d e n s i t y basement rocks ( ~ o n s d a l eand F l a v e l l e , 1963). The e a s t e r n f l m k has been made t o agree with t h e g r a v i t y i n t e r p r e t a t i o n . I n t h i s i n t e r p r e t a t i o n a density within t h e basement rocks mas invokcd t o explain t h e p o s i t i v e anomaly at Mount Charles. The i n t e r p r e t a t i o n of t h e e a s t e r n f l a n k as a monocline i s i n agreement with t h e r e f r a c t i o n south-west from Warburton ldission by Hunt O i l Company (1

It was concluded above t h a t t h e 16,600 t o 17,000 f t / s v e l o c i t y measured on a l l t r a v e r s e s from Mount Charles t o fdount Beadell o r i g i n a t e d a t about r e f l e c t i o n Horizon A. This horizon as defined by both r e f r a c t i o n and r e f l e c t i o n seems f a i r l y f l a t and i s shown i n P l a t e 4 at 2 depth of about 5000 f e e t from nqount Samuel t o beyond Mount Everard. Evidence of angular unconformity below t h i s horizon i s given by t h e 18,200 f t / s r e f r a c t o r at Vount Samuel and by t h e r e f l e c t i o n s e c t i o n s at NMF' 19 and Mount Everard. Local g r a v i t y anomalies appear t o o r i g i n a t e at depths of a few thousand f e e t and must r e f l e c t density v a r i a t i o n s within t h e sedimentary s e c t i o n , probably c o n t r o l l e d by s t r u c t u r e . From d i s c u s s i o n s i n Chapters 2 and 3 it seems l i k e l y t h z t some negative anomalies may be a s s o c i a t e d with t h e incompetent core rocks of decollement o r diapiric-type folds. The v e l o c i t y of 19,950 f t / s recorded i n t h e c e n t r e of t h e Mount Charles t r a v e r s e may be a s s o c i a t e d v ~ i t ha r e s i d u a l g r a ~ t y 'low', which appears as an i n f l e c t i o n i n t h e g r a v i t y g r a d i e n t forming

*

t h e northern s i d e of t h e EIovnt S~1.muel Gr2,vity Low, a t t h e minus 40n i l l i g a l ccntovr. Tiiis i n f l e c t i o n appears es tliovgh i t m y be a l i n e a r r e s i d ~ c . 1f e a t u r e p e r a l l e l t o t h e axis of t h e IJount S m u e l G x v i t y Low. The r e f r a c t o r could be t h e exposed core of a corresponding diagiric fold. The 16,203 f t / s v e l o c i t y recorded st Novnt Same1 i n d i c a t e s a n ezs-i; dippifig refractoi-. It could be on t h e north-east f l a n k of t h e a n t i c l i n e passing beneati; Brown6 Mos. 1 and 2 s e l l s . The a s s o c i a t e d s u r f a c e t r e n d i s ' n a p p e a ' t o within f i v e miles south of t h e t r a v e r s e . An event recorded from SP 800 zt l D b F 'I 9 shm-IS 2n apparent v e l o c i t y of 20,800 f-t/s. Depth conputatioon slising assumed t r u e v e l o c i t i e s of both 10,200 and 20,300 f t / s put Lhe r e f r a c t o r a thousznd f e e t be: ow t h e apparently w s s i v e 15,830 f t / s r,n f r i ~ c t o ri5ihich i s c o r r e l a t e d ~ i t U;oper h Proterozoic rocks. The event could be a s s o c i z t e d with a g e s t e r l y 6 l p p i . n ~i:ef~i.c:.ctor having a -true veloci-by of e'oo~l-t 1 8,200 f-t/s, s:imilar t o .[;112t reco:rded xi; 1,:Iovn-t Samuel. The west dip lrrould be i n agreement ivith t h e mean d i p s11o:iin by reflec-Lion events from about t h e same de2th. IIoi:~ever, t h e attenvz,ting ilat.~weof t h e event does ilot agree v i t h t h a t ~t T,lount Samuel. The favoxred ii1";rpretstion i s t h a t t h e event comes from a t h i n high v.elocity l a y e r within t h e Upper P r o t e r o z o i c sequence, probably limestone o r d o l o n i t e . The c r o s s - s t r u c t u r e i n d i c a t e d by s u r f a c e 'geology a t t h e northern end of t h e t r o x h i n t e r s e c t s t h e YilU? 1 c t m v e r s e . It i s seen from t h e TQ!P19 r e f l e c t i o n s e c t i o n t h a t a turn-over e x i s t s i n t h e s e d i m e n t a ~ js e c t i o n a t depth and would appea,r t o be of g r e a t e r amplitude below Horizon A.

It was concluded above t h a t t h e r e f r ~ . c t o r shaving v e l o c i t i e s from 10,OC)O t o 11 ,000 f t / s a t lklount S m u e l , P U ~ F19, and l ~ l o Beadell ~ t were of Termian age. I n Chapter 9 i t nas seen t h a t t h e s e r e f r a c t o r s ap2eared t o be t h i n high v e l o c i t y l a y e r s n e a r %he t o p of t h e Permian s e c t i o n . IjIostly t h e s e r e f r a c t o r s i n d i c a t e f l ~ t - l y i n gbeds s e v e r a l hundred f e e t deep. Only a t L!ount Samuel a r e t h e r e i n d i c a t i o n s of a p p r e c i a b l e d i p and p o s s i b l e thickening of t h e M?sozoic s e c t i o n at t h e e a s t e r n end of t h e t r a v e r s e . St r u c t ~ w a li n d i c a t i o n s at Lake Keene

I n P l a t e 2 t h e Lake ICeene seismic t r a v e r s e i s seen t o be i n t h e c e n t r e of a l a r p s g r a v i t y 'low1 Feature No. 1 , t h e Ilerbert I n P l a t e 24, r e f l e c t i o n s occming dov~nt o Gravity Sub-Depre~sion. t h e bottom of t h e s e c t i o n might i n d i c a t e u n d i s t o r t e d sedimentary l a y e r s down t o about 50,000 f e e t . A s pointed out i n Chapter 9 t h e s t r o n g e s t r e f l e c t i o n has a c e n t r e time of 4.2 seconds, equivalent t o a depth of 38,000 f e e t . The assumed average v e l o c i t y mithin t h e overlying sediments of approximately 19,000 f t /s g i v e s a l s o a s l i g h t west d i p of 2 degrees. This v e l o c i t y wtr be somewhat high and a l o n e r v e l o c i t y mould g i v e a correspondingly s m l l e r depth and g r e a t e r dip. I n P l a t e 4 t h e metamorphic basement has been ioined t o t h e s t r o n g event at 38,000 f e e t . There i s very l i t t l e j u s t i f i c a t i o n f o r t h i s procedure but t h e depth i s v o h a b l y of t h e r i g h t o r d e r and a basement configuration i s produced v~hichi s i n q u a l i t a t i v e agreement with t h e regional gravity profile.

-

I n P l a t e 3 t h e Lake Keene t r a v e r s e i s seen t o be approximately i n l i n e \qith t h e c r e s t of an a n t i c l i n e where it s t a r t s plunging t o t h e e z s t . The s t r u c t u r e i n t e r p r e t e d from aeromagnetic measurements i s a s s o c i a t e d mith a r e l a t i v e l y shallow e x t r u s i v e l a y e r (Lynch, 1965)., which h a s been c o r r e l a t e d above t h e 16,050-ft/s r e f m c t o r . Refracted a r r i v a l s n i t h a high v e l o c i t y of 19,120 t o 19,750 f t / s d e f i n e a r e f r a c t o r dipping e a s t from a minimum depth of 3500 f e e t . Shotp o i n t i n t e r c e p t s i n d i c a t e deepenjng of t h e r e f r a c t o r t o t h e west a l s o . The shallower 16,350-ft/q r e f r a c t o r , ~vhichh a s been t e n t a t i v e l y c o r r e l a t e d with t h e 16,610 t o 17,000-ft/s r e f r a c t o r f u r t h e r e a s t , shows a small amount of turn-over. The r e f l e c t i o n s e c t i o n i n P l a t e 24 shows a f l a t basement at 38,000 f e e t (?) dipping g e n t l y t o t h e west. There i s an i n d i c a t i o n i n t h i s s e c t i o n of s t e e p e r e a s t d i p at shaLlover depth. The o v e r a l l p i c t u r e i s c o n s i s t e n t with decollement o r d i a p i r i c t y p e f o l d i n g . The 19,120 t o 19,750-ft/s r e f n c t ~ rcould be a massive P r o t e r o z o i c limestone o r dolomite i n t h e core of t h e f o l d . CONCLUSIONS The follovring conclusions a r e drawn n i t h regard t o t h e e f f i c a c y of t h e seismic method i n t h e a r e a of t h e BMR seismic t r a v e r s e : 1.

The r e f l e c t i o n method can give usable r e s u l t s on a r e a s of Cretaceous outcrop, provided s u f f i c i e n t l y l a r g e numbers of geophones and shot-holes a r e used i n twodimensional a r r a y s . .

General comparison with more recent surveys has shovm t h a t e f f o r t s of t h e same o r d e r using t h e 'Thumper' and 'Vibroseis' s u r f a c e i n p u t methods give comparable r e s u l t s . These l a t e r surveys have a l s o sho~vnt h e p o s s i b i l i t y of obtaining improved r e s u l t s mith a C.D.P. t eclmique

.

2.

The r e f r a c t i o n method can be used t o f o l l o a two p r i n c i p a l r e f r a c t o r s having v e l o c i t i e s between 10,000 and 11,000 ft/s and between 16,300 and 17,000 f t / s .

Deeper and h i g h e r v e l o c i t y r e f r a c t o r s may be follorved i n p a r t s of t h e a r e a . In p a r t i c u l a r an a p p a r e c t l y massive r e f r a c t o r having a v e l o c i t y of 19,320, t o 19,750 f t / s has::been followed on t h e Lake Keene t r a v e r s e and a r e f r z c t o r having a v e l o c i t y of about 20,500 f t / s has been recorded i n t h e Mount Samuel Gravity Low.

3.

It may be p o s s i b l e t o map deep sedimentary structlme and basement configuration with a simple and r a p i d r e f l e c t i o n technique using l a r g e o f f s e t s , as at Lake Keene.

The main conclusions drann with regard t o t h e geological o b j e c t i v e of t h e survey a r e s e t out below. They a r e a l s o swnmarised i n diagramatic form i n P l a t e 4.

of t h e Permian s e c t i o n . The r e s u l t s of t h e sonic log i n Yowalga No. 2 well support t h i s assumption. The base of t h e Permian s e c t i o n i s undefined although t h e boundary i n d i c a t e d i n P l a t e 4 i s a p o s s i b i l i t y .

7. '

8.

Nothing has been found t o shoa that t h e Mesozoic s e c t i o n i s anything o t h e r than a t h i n veneer of f l a t - l y i n g rocks as expected from surface geology. A p o s s i b l e s l i g h t thickening of t h e sequence occurs under Mount Samuel i f t h e i n t e r p r e t a t i o n of t h e Mount Samuel r e f r a c t i o n probe i s c o r r e c t . This thickening v~ouldcoincide with a surface syncline mapped by photogeology, A n t i c l i n a l f o l d s , below t h e unconformity within t h e Upper Proterozoic, possibly occur a t Mount Charles, betvieen J!DfF 19 and hlount Samuel, and a t Lake Keene.

These f o l d s cannot be p o s t u l a t e d on seismic evidence. A tenuous j u s t i f i c a t i o n i s found only i n t h e combination of geology, g r z v i t y , aeromagnetic , and seismic r e s u l t s . 9.

The c r o s s - s t r u c t u r e i n d i c a t e d by photogeology at t h e north-western end of t h e Mount Samuel Gravity Low occurs at depth.

In t h e e~?-* t h a t t h e above conclusions a r e c o r r e c t and u n l e s s t h e p o s s i b i l i t y of Upper Proterozoic o i l i s a l l o n e d , it would appear t h a t t h e f i n d i n g of s i g n i f i c a n t amounts of accumulated hydrocarbons i n t h e v i c i n i t y of t h e BIAR t r a v e r s e i s u n l i k e l y . It i s of i n t e r e s t t o note t h a t hydrocarbons were found i n t h e e v a p o r i t e sequences a t t h e base of both Bromne No. 1 and Bromne No. 2 n e l l s ( ~ a c k s o n , 1966b).

It must be remembered t h a t some of t h e above conclusions a r e h i g h l y s p e c u l a t i v e and, i n p a r t i c u l a r , those concerning t h e nature a d age of t h e upper p a r t of t h e s e c t i o n a t Lake Keene. It i s recommended t h a t a s t r a t i g r a p h i c h o l e be d r i l l e d on t h e a n t i c l i n a l s t r u c t u r e at Lake Keene.

1.

2.

A t h i c k sedimentary s e c t i o n e x i s t s along t h e whole length of t h e BMR seismic t r a v e r s e , t h e maximum thickness measured being a p o s s i b l e 38,000 f e e t a t Iake Keene.

.

The t r a v e r s e appears t o c r o s s two major troughs, vhich correspond t o t h e ltlount S m u e l Gravity Lorn and t h e Herbert Gmvity Sub-Depression. Rough i n d i c a t i o n s mere obtained t h a t r e g i o n a l g r a v i t y f e a t u r e s b e a r a d i r e c t r e l a t i o n t o aetamorphic basement configuration.

The amount of seismic evidence obtained shoving t h e depth t o metamorphic basement i s small. As already pointed o;.t, t h e 20,500 f t / s r e f r a c t o r could l i e within t h e sedimentary s e c t i o n . The depth t o mctamorphic basement i n t h e Mount Samuel Gravity Low could be g r e a t e r and more nearly equal t o t h a t i n t h e Herbert Gravity Sub-Depression. The aeromagnetic work i n t h e Mount Samuel Gmvity Low, which i n d i c a t e s a depth t o magnetic basement similar t o t h a t shown i n P l a t e 4, was sparse.

3.

The g r e a t e r p a r t of t h e sedimentary s e c t i o n i s of Upper Proterozoic age.

. A s a r e s u l t of t h e BMR survey, it was thought t h a t t h e 16,300 t o 17,000-ft/s r e f r a c t o r mould be about t h e top of t h e Proterozoic s e c t i o n but t h a t t h e unknown s e c t i o n a t shctllob7er depth might be explained Lower Palaeozr~ict o Upper Proterozoic sandstone mapped by Wells (1 963 at t h e Iragana I n l i e r .

4

A major a n g u l r r unconfomity e x i s t s within one o r two thousand f e e t of t h e t o p of t h e Upper Proterozoic sequence. Sediments below t h i s unconformity have been subjected t o f o l d i n g , mhich was probably due t o s a l t movement and which was p a r a l l e l t o t h e edge of t h e basin i n t h e ljlount Samuel Gmvity Low.

This conclusion was drawn from t h e r e s u l t s of t h e Yosalgs seismic survey combined with g r a v i t y , surface geology, and t h e r e s u l t s of t h e Bronne and Yowalga w e l l s . , There vere i n d i c a t i o n s i n t h e r e s u l t s survey and t h i s model allowed t h e p o s s i b l e explanation of t h e BLlR~.~seismic of various s c a t t e r e d r e s u l t s .

5

The two o r t h r e e thousand f e e t of s e c t i o n above t h e angular unconformity and below t h e base of t h e Permian i s probably Lower Palaeozoic o r Upper Proterozoic sandst one. It appears t o be r e l a t i v e l y f l a t -lying although t h e f o l d i n g movement appzars t o have continued t o some extent a f t e r erosion took place.

6.

The Permian se?uence may be up t o 2000 f e e t tliiclc. i s mainly f l a t - l y i n g .

It

I n i n t e r p r e t i n g t h e r e s u l t s of t h e BlJR seismic survey it had been assumed t h a t t h e 10,000 t o 11,000-ft/s r e f r a c t o r l a y n e a r t h e t o p

ADASTRA ; Y U P I N G GEOPHYSICS FIY LTD

1965

An a i r b o r n e magnetometer nl?-rvey of & s t e r n O f f i c e r Basin: O i l Ekploration Lease O.E.L. f o r Exoil Pty Ltd.*

2d, S.A.,

BAZ~%LPI, K O . , and JACKSON, P.R.

1965

Lennis-Breaden Gravity Surveys, Officer Basin, Western A u s t r a l i a , Hunt O i l Company."

BblR

1960

Teot onic Map of A u s t r a l i a

DAVID, T.B.E.

1950

THE GEOLOGY OF T I B C O ~ ~ ~ ~ ~ O ~ ~ ' J E A L T H OF AUSTRALIA; London, Edward Arnold and Co. Vol 1 p. 695

FOIIJLER, K.F.

1963 -

Giles-Carnegie seismic survev, " , W . A , 1962. Bur. Min. Resow. Aust. Geoph. Progress Report 1963/8.

GOODENE, P.E.

1961

Rawlinson Range-Young Range aeromagnetic reconnaissance survey, W.A, 1960. Bur. ILin. Resow. Aust. Rec.

HORVflTZ , R C and o t h e r s

1966

Geological map of Western A u s t r a l i a . Geological Survey of Western A u s t r a l i a .

13Ul?T OIL COMPANY

1965

F i n a l Report on Warburton seismic survey, Vi. A .*

JACICSON, P.R.

196&

Hunt O i l - P l a c i a O i l Well Completion Report No. 2 Yonalga.*

JBCIEON, P.R.

1 966b

Geology and reviev~of e x p l o r a t i o n , O f f i c e r Basin, Western A u s t r a l i a . Hunt O i l Company F.eport.

1958

P o s s i b l e g3odetic survey ssction of ground reconnaissance from blount Harvest t o Carnegie Ilomestead. Division of l?ati o n a l Mapping Reoort (unpublished).

1964

Babbagoola seismic survey, Hunt O i l Company .*

1965

Aeromagnetic survey Polack H i l l s a r e a f o r A u s t r a l i a n Aquitaine Petroleum Pty Ltd.*

<

..

ICENDALL, T.L., HARTLFK, D.A.

and

LEETOM, B.K. and m!D80NS , R ,H

.

-

.. 48 .;' L . ,. +

LESLIE, R.B.

"

*. Geology of t h e Gibson Desert, Western Australia.

1961

fioni+%ken H i l l Pty. Ltd., Rep. No. 3000 G - 38 (unpublished).

-

LONSDALE, G.F., and FLAVELLE , A . J

.

LYIJC'H, Vance M.,

MACK, J.E., and Hl!B.RImT, F.A.

Amadeus and South Canning Basins reconnaissance g r ~ v i t ysurvey using h e l i c o p t e r s , ~ ' 2and FA, 1962. Bur. Idin. Resow. Aust. Rec.. 1963/152.

1963

.

.. .:..::;>., . . 1965 . , :...

Airborne magnetometer survey of t h e Gibson Desert a r e a . Union O i l Company of California*.

1965

Reconnaissance geological survey of t h e Alliance Gibson Desert block PE205H, 20613, 207H Western ~ u s t r a l i a .Union O i l Developments Corporation; G.R. No. 1 8 (unpublished).

.

p~

1961

Wave-front diagrams from uphdie shooting. Geophysical Prospecting 9(4) 9 533-543

I,JIICISLIE~EBRY,R.K.,

1364

Yowalga seismic survey p l u s extension. Hunt O i l Cornpaw.

li1OSS, F.J.

1 962

Amadeus Basin (Ssuthem. l!rgin) seismic survey, Northern T e r r i t o r y , 1961. B u r . l i n . Res. Aust. Rec. 1962/167.

SOFOULIS,

J.

1962 ,

..

Plater supplies, Warburton Range and' iflj~ . i n i n ga r e a s . Report of t h e Department of l b e s , w e s t e m A u s t r a l i a , 1961 pp 61 -63.

.

SOFOULIS, J.

1963

The occurrence and hydrolopacal s i g n i f i c a n c e of c a l c r i t e d e p o s i t s in-west e r n A u s t r a l i a . Report of t h e Department of f i n e s , Western A u s t r a l i a 1961, pp 84-88.

VALE, ILR.,

1960

A discussion on c o r r e c t i o n s f o r weathering and e l e v a t i o n i n e x ~ l o r a t i o nseismic work. B&. E n . Res. Aust. Rec. 1 960/13.

VALE, K.R.,

1965

Progress of t h e reconnaissance g r a v i t y survey of A u s t r a l i a .

49 VALE, K.R. and SCIITH , E R ,

..

.

1961

The depth probing technique using seismic r e f r a c t i o n methods. Bur. IEn. Res. Aust. Rec. 1961/79.

VEEVmS, ,1 J. and YELLS, A.T.,

1959a Probable s a l t dome at Woolnough H i l l s , Canning Basin, Western A u s t r a l i a . Aust J Sci 21 (6) 1 93-1 94.

VEVEBS, J.J. and \,TELLS A.T. ,

1959b Probable salt dome a t \Voolnough H i l l s , Canning Basin, Western A u s t r a l i a . Bur. hlin. Res. Aust.

. . .

Rep. 38. VEWERS, J.J., and 'FELLS, A.T.,

1961

The geology of t h e C m i n g Basin, Western Australia. Bur. hlin. Res. Aust. Bull. 60.

PIflTSOlT, S . J . ,

1963

Giles-Carnegie Seismic Traverse, WA and SA, 1961, Bur. PZin. Resour. Aust. Rec. 1963/7.

?EBB, E.A.

1965

W i l l Officer and Amadeus B ~ ~ i n s

both be productive? -World 0 _1 160(7) , 160-1 65.

YELLS, A.T.,

1 960

Summary of A c t i v i t i e s 1960 Sedimentary Basins. Bur. E n . Res. Aust. Rec. 1960/-

?ELLS, A.T.

1963

Reconnaissance geology by h e l i c o p t e r i n t h e Gibson Deset-t, VIA. Bw. I i n . Resour. Aust. Rec. 1963/59.

YELLS, A.T., FORiJ'A.lLT, D . J . and RANFORD, L.C.,

1964

Geological reconnaissance of t h e Ra.r~linsonand hIacDonald 1 :250,000 Sheet a r e a s , Western A u s t r a l i a . Bur. Min. Resow. Allst. Rep. 65,

\'TELLS, A.T., FORfJA.lJ, D . J . , and RANFORD, L.C.,

1965

'

)

*

The geology of t h e north-western p a r t of the Amadeus B ~ s i n .Bur. Itin. Resour. Aust. Rep. 85.

Unpublished r e p o r t on a Commonwealth-subsidised operation

50. A?PE!YDIX A STAFF

AND E Q U I ? l ' T

Staff

Party leader Geophysicists Surveyors from Dept of the Interior Clerk Observer Shooter Toolpusbsr Drillers

Mechanic F i e 1 d-hands

S.J. Watson K.F. Foviler A. Turpie (from 14. hnckncki R. Leethaa . E. J. Quinn G.L. Abbs R.J.E. Cherry J.G. H a l l s J. Chandler R.O. L a r t e r J . Iceunen A. Z O S ! ~ I.D. P i r i e

4) 0)

A.. Turpie .$ P. Fo-uler G. Bow IJ. b d i n ( t o 22/10) T. Howard R. Leetham P. Short ,J.I<. Grace C. Wood J.G. k l l s J . Chandler K. Suehle J. Keunen L. Watts '

E. Macintosh

13

11

(2 cooks, 1 mechanic, 1 t a n k e r d r i v e r , 3 recorder crew, 1 s h o o t e r ' s o f i s i d e r , 1 s t o r e s d r i v e r and n i s c e l l a n e o u s , and 2 surveyors a s s i s t a n t s ; p l u s 2 d r i l l a s s i s t z n t s i n 1962 o n l y ) . Equipment Seismic a m p l i f i e r s Seismic o s c i l l o g r a p h Tilagnet i c r e c o r d e r Geophones

Transceivers (~ommunicationsand time-breaks) Blasters Drills

Note:

.

Texas Instruments 7OOOB Electro-Tech ET66 Electro-Tech CS7/700 612 T . I . C . and Electro-Tech, 20 c/s i n grouys of 6 100 T.I.C., 6 c / s (1961) 100 EVS 8B 4.5 c/s i n groups of (1 962) 3 Traeger 59 ldl10 3 Traeger 'I'M 2 (1962 only)

1 1 1 1 1 2

Electro Tech, BC-2-5 S.I.E., SCD 2000A T.1.C 1hyhev1 1000 (from 2/10/62) F a i l i n g 750 Carey

Whereas communicatinns had been almost non-existent i n 1961 using t h e Traeger fr 9 Ill1 0 on 21 40 Kc/s, communications were e x c e l l e n t i n 1962 using t h e Tkl 2 on 681 5 Kc/s.

4

Vehicles Land Rovers L.W.B.

Land Rover S t a t i o n Wagon International

4 x 4, 1 ton, AA120 Bedford Truck 4 x 4, 3 ton

I n t e r n a t i o n a l Rl YO 4 x 4 (from '20/10/62) Chamberlain Tract o r 4 Wheel T r a i l e r s , 4 t o n

4 'Yheel T r a i l e r , 30 cwt. Office Caravan

. . . . ..

2 Geophone Trucks 2 Surveyors

1 General Purpose (1 962 only)

1 Party Leader's Ute. 1 Recording Truck 3 Tankers, 700 g a l l o n 1 Tanker, 1000 gallon 1 Shooting Truck 1 Workshop Truck 1 Stores Truck 2 Carey Drills 1 Failing Drill 1 Mayhew D r i l l 1

2 1 1 1 1

Tmy Body Kitchen Magaz!.ne Work&op Spares .

TABLE OF OPERATIONS

S e d i m a n t ~ r yBasin Area Camp s i t e s Shooting commeqced Shooting ceaced Miles surveyeG Topogr;. n h i c survey c o n t r o l Total footage d r i l l e d Explosives used No. of detona+ -?s used Datum l e v e l s f o r c o r r e c t i o n s ( f e e t above s e a l e v e l )

Source of r e f l e c t i o n velocity distribution l e t h o d used i n r e f r ? c t i n n computation Idethod used i n weathering computation

Officer lllovnt Davies t o Mount Beadell 1 . G i l e s 9 t h t o 22nd September 2. Sigmpost 23rd September t o 23rd October 6 t h September 18th October 13% hISL P o r t Augusta 5463 3016 l b Geophex 206 Irlount Cavies 2000 i900 Giles Ranlinson 1800 i 600 Lake Hopkins Lake Christopher 1300 signpost 1600 Ilount Charle s 1500 X'Iomt Samuel 1450 Nl"nI'F I q i400 1~1ountBzsdell 1450 Iragana Turn-off 1650 Velocity shoot at ll!oun-t Readell (1 962) : Vale and Smith (1 961 ) : Vale (1 960), r e c i p r o c a l time nethod

Reflect i o n Shoot i n a Data Shot-point ir t e r v a l s Geophone groups

1320 f t

6 x 20-c/s geophones i n l i n e at 22-ft i n t e r v a l s

Geophone group i n t e r v a l !?umber of h o l e s shot Niles traversed Usual recording f i l t e r s U s u a l playback f i l t e r s Common charge s i z e s Common shooting depth

110 f t 21 6$ m i 1 3 9 ICl 8 K75 K30 K57 5 t o 10 l b 50 t o 100 f t

R e f r a c t i o n Shooting Data Geophone grocps Geophone group i n t e r v a l Bunber of h o l e s shot Usual recording f i l t e r Number of r e f m c t i o n t r a v e r s e s

: 2 x 6-c/s geophones i n p a r a l l e l : 220 f t : 49 : KO K57 : 11

b

.

Charge s i z e s 1,Tiles t r a v e r s e d 1 1 : k i n m shot-to-geophone distance 1962 : Officer : 1i'loun-t Charles t o Lake Keene : IJalfrrlagr between I ~ Y1D 9 and Itbunt Beadell : 18th September : 4 t h December : 138 : Queensland S t a t e Datum : 44,688 f t : 11 ,267 l b Geophex 3,200 l b I l i t r o l i t e

Sedimentarj basin Area Camp s i t e s Shooting comenced Shooting completed l'liles surveyed Topographic survey c o n t r o l T o t a l footage c l l i l l e d Ekplosives used

Datum

Traverse

(ft

A.s.L.)

V0

(

ft/s 1

Signpost h1ount Charles

1600 1450

1000 4000

Mount Samuel lQ,F19

A50 1400 Refln. 1450 Refrn. 1450 1450 1300

3000

BIo~mtBeadell F~Tount Everard Lake ICeene Source o f v e l o c i t y distribution Reflection -

V e (ft/s) 6000

( 8800 ( 10,250 7600

3200 7000 3000 10,000 1000 7000 5000 9000 : &tended-spread v e l o c i t y s k o ~ t a t 1,Iount Beadell

Shootinn h t a

Shot-point i n t xrvzl Geophone group Geoplione groug i n t e r v a l Holes shot:

(b) 1800 f t : ( a ) 1320 f t : See r e f l e c t i o n s e c t i o n s : (a) 1 1 0 f t (b) 150 f t

Description

Depth

S i n g l e shallow S i n g l e shallow S i n g l e deep S i n g l e deep S i n g l e deep 3 deep-Shot-hole pattern C 7 deep-Shot-hole pattern B 36 shallow-Shot-hole pat t e r n A IJiles traversed

Number shot

Purpose

27

Weat h e r i n g Noise t e s t Noise t e s t Weathering Uphole shoot Comparison

7 7 31

4 h o l e s 76 s h o t s 2

9 33

Usual recording f i l t e r Usual playback f i l t e r Comnon charge s i z e s Weathering c o r r e c t i o n s Gmding system

Reflection traverse Reflection traverse extended-spread

: 65- miles + velocity : 18K t o 66K : 24IC t o 57K : ( a ) 36 x 2/3 l b (b) 36 x ZX l b : Vale (19601 : &by (1 947

R e f r a c t i o n Shooting Data Geophone group

Geoplione group i n t e r v a l Holes shot Us--1 recording f i l t e r lh.1mber of r e f r a c t i o n t r a v e r s e s Charge s i z e s l!hinum shot -to-geophone dis-l;ance Westhe r i n g con-I;r o l Weathering end e l e v a t i o n c o r r e c t i o n s

: Four EVS 8 4.5 c / s 22-ft i n t e r v a l s i n a t r i g h t angles t o traverse : ( c ) 220 f t ( d ) 300 : 80 : 0, 57IC

Mount hbunt Mount hbunt

ft

5

: 10 t o 1600 l b : 17% miles : Reflection spreads s h o r t r e f r a c t i o n and uphole shoots : Vale (1 960), r e c i p r o c a l time method

Notes (a) (b) (c) (d)

at a line the

Beadell, 1Q1P 1 9 Eberard Charles, NlIF 19, Iilount Beadell Samuel, hlount Everard, Lake Keene

S90T-ROLE IRILLIHC- STATISTICS

Seismic shot-point k i l l i n g Drilling rigs T o t d footage b i l l e d Ho. of h o l e s d r i l l e d Average de2S.'1 of h o l e Deepest 1101e b i l l e d Drilling t h e T r a v e l l i n ~and rigging-LI~ time T i m e - l o s t standing by r e c o r d e r Time l o s t s a i - t i n 6 f o r n a t s r Tine Lost becouse of stuck pipe ?To. of s h i f t s worked L Q i ~ t e n s : n ct ~o d r i l l s Bentonite used Drilling rate.

2 Careys

5739 156

37 ft 150 f t 169:: h r 143': h r 26 63 h r 2 hr

53

81 h r 6 & bags 33.8 f t / h r

'$later-bore c h i l l i n g

..

T o t a l footage d r i l l e d No. of h o l e s G r i l l e d D r i l l i n g time T r ~ v1e1-j..?*.: t i n e Tine t a k e n ? a i l i n g s n d casing t , i ~L ~ ~ l;?ild e s settinpup t h e pun? head floe of 5 h i f . t ~i,qorked

665

7 201 i2 hr 165 h r

4.1 5 h r

9

(includin@ v a t s r bore and core llolos) T o t a l footsge d r i l l e d T o t a l Wo. of h o l e s d r i l l e d Average depth of h o l e s Dee2es.t Llole d r i l l e d T m v e l l i n g Line and r i g g i n g up Time l o s t i:~a.i-Lingon water Tine l o s t r e p a i r s t o d - r i l l Time l o s t because of r a i n Time l o s t r e p a i r s t o engine rig Tine waiting on s u r v t y o r s Time l o s t stend by r e c o r d e r D r i l l i q time To. of h i f t s ir!ori:ed i s h i n tens;nce t o &lll Bentoni.l;e used job -'~islij-ng -

710 h r I 3s 1~02; r

I'

5 bags 24"!"4

Drilling rate Running casing and baling Freeing bog.-ed vehicle Working on bore Note: The time l o s t a a i t i n g f o r water ses m i n l y due t o t h e breakdorm of water tankers.

k f i n g t h e e-.rly p a r t of t h e sulvey m t e r was o b t e i l e d from m b l i s h e d bores 8'~ Uomt 32vies, Giles T.Ieteorological Sta-tion,and iiIc7,,-r5urtot7,l
lT/zter~ ~ forsnd 2 s a t 15 f e e t i n shot-holes a t 1iToun.t S m ~ x e l .

PLATE 6

OILLa- U I X L O I I P l W l C WIVE*

I*.)

TRAVERSE NMF R

ISOCHRONS FROM UPHOLE SHOOTS TO ACCOMPANY RECORD No. 1967/123

G52/ 03-51

-

GI LES CARNEGIE SEISMIC SURVEY WA, 1961/2

RESPONSE CURVES FOR HOLE AND GEOPHONE PATTERNS

EZ1/1961'ON

OL1033LI ANWdW033Q 01

El -E8 / IS9

Zb SLY 31s OJluJ3 ~ J o O b l d SWtWS3#

2

/OJOUlW /O noJJn8 'ON

. :A

'

8 N01133S

4 ~ 0 dJlUSJOS : A 0 03080338

-I

-

3SU3AVUl S31UVH3 l N f l O W

-

1961 ' A 3 ~ t I l l S 31WS13S 3193NtlV3- S3119

owz

om

odm o m m 3 7 V 3 S 1VlNOZltlOH

0 0

( pa(sn!pc. 1 tunow P I L ~ S10 zx :zi

~ S J ~ A D J Illapoag

NOllVWtlOJNI

A113013A

suo!tDas aas :

2-

:

~U/~!SO~LUO~

/D/~P

:I!!/

0s-

:lDU!j

OE-

~ o l s~ a d n s

:

09/1 - GZ/I

:

r,

@JL

U!D9

3.9.r S.1

SJalLlj

.

,

NOllVWtlOJNI Y 3 V 8 A V l d xaqdoa9 s q l o l ' s : a610113 14 00101 ZG :wdaa aloq ~ I ~ ' J ! s :

u ~ a l i o daloq-ioqs

14011 lohlaiu! uo!iois au!l u! (lodo (4 2 2 ' a 3 o ~ +l a d g :

u ~ a l l o dauoqdoa9

s/3 0 2 ' 8 1 S A 3 ' 1 1 . 3 aP OE-

:I

09-

:

sauoqdoag

D V ~

'2'9.r

:

UlD9

:/4/l!ul '6.M

:sJ~ll!J

S L Y - 81Y

8000L ' I 1 a : s ~ ? ~ j ! l d ~ ~ OOL

'

JaPJ03aC/ .?/laubo~

1'1.3

NOIlVVUklOJNI 9NlatI033U

e-:

SlNlOd -1OHS

5101 .

PI01

2101

a01

1/01

GI01

bIO1

‘

2101

ZlOl

1101

GI01

b101

S101

ZlOl

1101

SlNlOd -1OHS

-0

SHOTPOINTS

"'

PLATE 16 912

913

914

915

911

912

913

914

9 15

911

912

913

914

'I5

SHOTPOINTS

CORRECTED RECORD SECTION

--

RECORDING INFORMATION E.TL. DS7/ 700

Magnetic Recorder

--

Amplifiers :

T. I.

70008

Filters : K18-K 75 A.G.C.:

W.B.

Gain Initial: Final

-60 -30dB

:

Geophones : E.T.L. EVS 2B, 2 0 c/s Geophone pattern

;

6 per trace, 2 2 f t apart in line Station interval llO f t

Shot - hole pottern : Single hole Depth : 68 to 8 6 f t Charge : 5, 101bs Geophex

'

.

PLAYBACK INFORMATION filters

1/25

:

A. G.C. : Gain

- 1/60

SuperUnmixed slow

Mixed

Initial:

-50

-40

Final:

-30

-20

Trip delay

:

Compositing

:

-2

See sections

VELOCITY t2

INFORMATION :

X2

at SP714 Mount Beadell traverse (adjusted

HORIZONTAL, SCALE

?

0

n x X , , q € J X X W ) @

FEET

2640

1320

GILES - CARNEGIE SEISMIC SURVEY, 1961

MOUNT SAMUEL TRAVERSE a

RECORDED B Y : Seismic Porw No. 2

SECTION B Y : I

I

NOTE: The trace polarity in fhe nuxed sections is r e v e ~ e d

Bureau of Mined Resources P/oyboch Centre S/E MS 42 TO

.

G51 /B3- 15

ACCOMPANY RECORD ~ 0 . 1 9 e 7 / l P

CORRECTED RECORD SECTION

SHOTPOINTS

811

812

813

814

815

811

812

813

814

815

SHOTPOINTS

PLATE 17

RECORDING INFORMATION Magnetic Recorder ETL. D S 7 / 7 0 0 Amplifiers

:

T. I. 7000 B

0.1

Filters

:

K 18 K7 5

0.2

A.G.C.:

0.3

Gain

o DATUM

W.B.

- 40, - 50, - 3 0 dB

Initial:

final

0.4

:

-60

Geophones ; E.T.L. EVS 28, 2 0 c / s Geophone pattern ;

0.5 0.6

6 per trace, 22ft apart in line

0.7

.

0.8

Station interval llO ft

.

0.9

Shot -hole pattern

1.0

:

Single hole Depth 7 2 f t - 116ft Charge 5,10,15 1b Geophex

1.1

1.2 I .3

PLAYBACK INFORMATION

1.4

filters

1.5

A. G.C.

:

Gain

Initial:

1.6

1/25 - 1/60.

:

Super slow -50

Final

1.7 z=3

B

C,

1.8 !$

-30

:

Trip delay

:

-2

Cornpositing

:

See sections

s 2P

1.9 'u 2.0 2.1 2.2

e&

VELOCITY

INFORMATION

t2 :

2.3

X2

at SP714 Mount Beadell traverse

2.4 2.5

HORIZONTAL SCALE 2.6 IOOO

0

2.7

2000

3000 1

I

1320

4000 1 FEET

2640

2.8 2.9 3.0

GILES - CARNEGIE SEISMIC SURVEY, 1961

3.1

NMF 19 TRAVERSE

3.2 3.3 3.4 35 '

RECORDED BY: Seismic /%fv NO. 2

Bureau o f Minem1 RBSOUTCBS P10ybock Centre S1E M S 42

SECTION BY

NOTE: ???etmce polarity on the mixed x f i o n is reversed

-

,

-

-'

.

,-,--TO

ACCOMPANY

G51/B3-ll

'

RECORD. No. 1967/123

PLATE SHOT.POINTS

:

808p

CORRECTED RECORD SECTION

SHOTPOINTS

*

RECORDING INFORMATION 0 DATUM

Magnetic Recorder

E.T.L DS7/ 700

0.1

Amplifiers

T.I. 7 0 0 0 8

:

K18 to K66

0.2

f i/terS :

0.3

A.G.C.:

0.4

Gain /nitia/:

0.5

Final:

0.6 0.7

W.B.

- 40, -50 Max

Geophones .;

E.T.L. EVS 2 8 2 0

Geophone pattern

;

2?

0.8 0.9

1.0

Shot -hole pattern

1.1

:

7 holes 4 4 f t apart in line Depth 8 0 ft Charge 7 x 21/2 Ibs Geophex

I .2

I .3 1.4

PLAYBACK INFORMATION

1.5

filters

1. 6 1.7

3

1.8

&8

:

1/25 - 1/60

A. G.C. ;

Super slow

/nitia/:

-4 0

final

:

-20

Trip delay

:

-2

Cornpositing

:

Gain

s

1.9 U ' 20*

9

2.1

See sections

$ c'

2.2$

VELOCITY

2-3

INFORMATION

2-4

t 2 : x2

2.5

at SP714 Mount Beadell traverse

2.6

HORIZONTAL SCALE 2.7 0

2.8

0

000

2000 1320

3opo

4000 ' FEET

2540

2.9 3.0 3.1

GILES-CARNEGIE SEISMIC SURVEY, 1962

3.2

NMF 19 TRAVERSE

3.3 3.4

RECORDED BY: Seismic Porw No. 2

35

SECTION B Y :

Bureou of Mineml Resources Ploybock Centre SIE MS 42 T O ACCOMPANY

NOTE

:

The trace poturify

the mixed sections is reversed

G51 /83-11-2 RECORD

No. 1987/123

. PLATE 19 SHOTPOINTS

SHOT.POINTS

CORRECTED RECORD SECTION RECORDING INFORMATION

0 DATUM

CUlTUY 0

0.1

0.1

0.2

0.2

0.3

0.3

0.4

0.4

.

Magnetic Recorder

E.T. L. DS7 / 700

Amplifiers :

T. I. 7000 B

Filters

:

K18 $-.K66

A.G.C.

:

W. B.

Gain

Initial:

-5 0

Final

Max

0.5

0.5

0.6

06

,. . . . "5.. .. .. .. .. ......

Geophone pattern

0.8

0.8

4

~

-

PLAYBACK

INFORMATION

Filters:

1/25-1/60

A. G.C.

:

Super slow

Gain

initial:

-40

fino/

:

-20

Trip delay

:

-2

Cornpositing

:

TRAVERSE

1 .3

13

'

........ . ............... ....

1.2

b2

4

Shot -hole potter?

1.1

I.I

22'

d'L

, /-

1.0

10

;

44':.

0.9

0.9

E.T.L. EVS2B 2 0 c/s

Geophones :

0.7

a7

:

-

:

-

D e ~ t h13ft

~

'44'

Charge 36 x 2/31b

1.4

1.4

1.5

1.5

1.6

/6 Y

9

$1.7

1.7

Q 1.8 e

1.8

u $j

gt9

1.9

$j

B

k 2-0

Bk 8 2.1

8 2.1

See sections

e 2 . 2$

$22 2.3

2 3

2.4

2-4

2.5

2.5

2.6

2.6

'2.7

2.7

2.8

2.8

VELOCITY

INFORMATION

12: x2 at SP714 Mount Beadell traverse HORIZONTAL SCALE

2.9

2.9 3.0

3.0

3.1

3.1

3.2

3.2

3.3

3.3

J.4

3.4

3.5

3.5

GILES -CARNEGIE SEISMIC SURVEY, 1962

NMF 19 TRAVERSE RECORDED B Y : Seismic Par& No. 2 SECTION BY :

NOTE

:

The trace polariiy on the mixed sections is reversed

Bureau of Mineral Resources Pfoybock Centre,S1E.M.S42

G51/83-11-3

TO ACCOMPANY RECORD No. 1967/123

CORRECTED RECORD SECTION SHOTPOINTS

"SHOTPOINTS

DATUM 6

0 DATUM

RECORDING INFORMATION Magnetic Recorder

0.1

Amplifiers

0.2

T 1. 7 0 0 0 B

:

K18

Filters :

0.3

A.G. C...

0.4

K75

W.B.

Gain initial:

0.5

E.T. L. DS7/ 700

Final

-50 , -60 - 3 0 Dbs

:

06

Geophones 0.7

E.T.L. EVS 28, 2 0 c/s

:

Geophone pattern

..

0.8

6 per trace, 2 2 ft apart in line 0.9

Station interval 110 ft

/.o

Shot - hole pattern : .\ 711, 712,713 50;

1.I

1.2 1.3

714, 715 Single hole Depth 8 0 f t Charge 10 Ibs

Depth 6 ft Charge 9x2!+ Ibs '

1.4

PLAYBACK INFORMATION

1.5

filters:

1/25-1/60

A G.C.

:

Super slow

Gain

lnlltal.

1.6

VELOC lTY

-40

INFORMATION

l e :x7- at SP714

HORIZONTAL SCALE

GILES - CARNEGIE SEISMIC SURVEY, 1961

MOUNT BEADELL TRAVERSE

NOTE: The

polorifi on the mixed section is reversed

RECORDED B Y : Seismic Porfy Nu. 2

SECTION BY

Bureau of Mineml Reswrces P/oyback Centre S/E MS 42 TO

ACCOMPANY

G51/83-12-1 RECORD

No1967/123

i

SHOT-

~ n l w r c,

DATUM 0

711

712

713

714

715

716

717

718

7 19

720

721

SHOT POI NTS

CORRECTED RECORD SECTION

0 DATUM

RECORDING INFORMATION E T.L.

Magnetic Recorder

0.1

PLATE 21

T I. 7000 8

Amp/ifiers :

Goin /nitio/; -50 Final Geophones

Max.

;

E.TL. EVS 28

.

Geophone pattern

.. 22'

....... Shot - hole patterc ...... . . .................... ..... 44'

;

..?4'

PLAYBACK

Charge 3C x

INFORLATION

Filters:

1, 25 - 1 / 6 0

A. G.C. .

Super sicw

Gain

Depth I?ft

/ n ~ ' t i a l -40 Final

P i p delay

:

-20

:

-2

See sectlons

VELOCITY t2 : x2 at INFORMATION SP714

HORIZONTAL SCALE 0

I'j""'

0

1000

2000

3000

I

1320

4000 FEET

2540

GILES - CARNEGIE SEISMIC SLIFiVEY, 1962

MOUNT BEADELL TRAVERSE

RECORDED BY

SECTION BY:

Se~srnicParty No 2 Bureou of Mineral Resources Ploybock Cenlre SIE MS 42

G:

'/3

PLATE 22

CORRECTED RECORD SECTION SHOTPOINTS

607

. 608

609

610

611

607

608

609

610

611

607

608

609

610

511

SHOTPOINTS RECORDING INFORMATION

DATUM 0

E.T.L. DS7/ 700

Magnetic Recorder

0 DATUM

T I. 7000 B

Amplifiers :

0.1

Filters: K18-K75

0.2

A.G.C.

0.3

W.B.

0.4

Final

Max

:

0.5

Geophones : E.T.L. EVS 28, 2 0 o h

...

Geophone pattern ..

22.

d2K

<-: .. .. .. .. ..

4 4 ' j

'......

44'f

.................*. ... a

TRAVERSE d

-

Charge: 36x2!'2

1/60

Filters:

1/25

A. G.C.

:

Super slow

Gain

Initial:

-40

Final

:

-20

Trip delay

:

-2

Compositing

:

.See sections

VELOCITY

INFORMATION

t * : x2 at SP714 Mount Beadell traverse (adjusted 1 HORIZONTAL SCALE 0 0

1000

2000

4000

XXK)

I

I

1800

3600

I

FEET

GILES - CARNEGIE SEISMIC SURVEY, 1962

MOUNT EVERARD TRAVERSE

NOTE: The trace polarii'y on the m i x e d sections is r e v e r s e d

RECORDED BY: Seismic Porw No. 2 SECTION BY

Bureou of Mineml Resources Ploybock Centre SIE MS 42

lb

-

MOUNT DAVIES

REFRACTION TRAVERSES TIME /DISTANCE

CURVES

HORIZONTAL SCALE 81

0

0

IIQO

2203

330J t

NOTE: VELOCITIES IN FT/S

TO ACCOMPANY RECORD No. 1967 / I 2 3

FEET