Deep Seismic profiling in central Australia

Tectonophysics, Elsevier

173 (1990) 247-256

Science Publishers

247

B.V.. Amsterdam

- Printed

in The Netherlands

Deep seismic profiling in central Australia C. WRIGHT

‘, B.R. GOLEBY

*, C.D.N.

COLLINS

S.A. GREENHALGH ’ Bureau of Mineral Resources,

‘, R.J. KORSCH

2 and S. SUGIHARTO

*, T. BARTON

‘,

3

C.P.O. Box 378, Canberra, A.C. T. 2601 (Australia)

2 School of Earth Sciences, Flinders University of South Australia, ’ Sceptre Resources Pty. Ltd., Jakarta (Received

October

5, 1988; accepted

C.D.N.,

Korsch,

R.J., Barton,

Bedford Park, S.A. 5042 (Australia) (Indonesia)

April 13,1989)

Abstract Wright,

C., Goleby,

B.R.. Collins,

seismic profiling (Editors),

in central

Seismic Probing

Deep seismic profiling

Australia.

of Continents

undertaken

refraction

work and a small-scale

reflection

profiling.

dipping mapping.

events that are interpreted The Redbank

defines

a marked

absent;

sub-horizontal

Seismic

refraction

Southern

the resolution

basement

Zone,

refraction

Australia

a major

velocity

of anisotropy

feature, below

long,-range

spread

incidence

Block in central

reflection

Australia

has been imaged Zone,

the Southern

show abundant

to depths

Arunta

reflections

are

Basin.

between

the

reflection

spreads

and

of special geological

interest,

and

rocks of the northern Arunta

northerly geological

and Amadeus

the boundary

Basin. Expanding

to the results in regions of the Central

dipping

Province both

in surface

of at least 30 km, and

steep, northerly

50 km thick below

in the sedimentary

in the granulites

Kennett

profiling,

part of the Amadeus

fine details

S., 1990. Deep

and B.L.N.

173: 247-256.

faults, many of which are evident

is more than

variations

J.C. Dooley

as well as the more usual near-vertical

South of the Redbank

and the northern

survey have added

of complicated

from dipping

are prevalent

that the crust

Provinces

the Anmta

thrust

expanding

survey,

S.A. and Sugiharto,

C. Wright,

Tectonophysics,

comprised

refraction

within

character.

reflections

indicate

Arunta

Basin and the measurement

sections

in reflection

profiles

and Central

a tree-dimensional include

in central

as reflections

Deformed

change

and their Margins.

three-dimensional

Seismic reflection

T., Greenhalgh,

In: J.H. Leven, D.M. Finlayson,

Province

part of the Amadeus

adjacent

to the Redbank

Zone.

In 1985, the Australian

Bureau

of Mineral

Re-

deep-reflection and long-range refraction profiling. Finally, some key results from expanding spread reflection and three-dimensional refraction

sources undertook a program of seismic reflection and refraction profiling across the Arunta Block

profiling are discussed. The implications tectonic evolution of the central Australian

and the Ngalia and Amadeus Basins in central Australia (Fig. 1). The purpose of the seismic work was to constrain the structure of the deep

are discussed et al. (1990).

crust and to test models of the geological evolution of the central Australian region. A summary of the seismic recording parameters is given by

The geology and evolution of the central Australian region

Goleby et al. (1988). In this paper we review briefly the tectonic problems that have been identified by earlier geological and geophysical studies, and present the most significant results of the

The Arunta Block (Fig. 1) has been interpreted as a Proterozoic mobile belt underlain by continental crust. It consists of three tectonic provinces, each with separate histories of deformation

in the companion

paper

for the region

by Goleby

AMADEUS

@----

ov

BASiN

Refraction

survey

f 1985/

Refraction

survey

(19881

Reflection

profile

(1985)

El, E2. E3 @-

Expanding

RDZ-

Redbank

GF - Gardmer

Road

M P - Missmnar

Fig. 1. Map of central reflection

spreads

Australian

and transmission

survey

area showing

tomography

location

experiment.

central

of seismic

The Arunta

and southern

and metamorphism (Shaw et al., 1984). The Redbank Deformed Zone (RDZ) that forms much of the northern boundary of the Southern Arunta Province is an easterly-trending zone of anastomosing mylonites, 7-10 km wide, dipping northwards at about 45”. In the region covered by the seismic profiling, granulite facies rocks of the Central Arunta Province have been thrust southwards over amphibolite-facies migmatitic gneisses of the Southern Province (G&son, 1987; Shaw, 1987). The Ngalia Basin covers much of the southern part of the Northern Province of the Arunta Block and contains Late Proteruzoic and Palaeozoic

spread

Three -’dfmensmnal

reflection

deformed

survey

zone

Fault y Plain

lines, seismic

Block is divided

(abbreviated

locations

refraction

refraction

into three tectonic

profiles, provinces:

expanding northern,

to STH).

sedimentary rocks of 6 km maximum thickness (to the west of the seismic profile of Fig. 1) that can be correlated with sedimentary rocks of the Amadeus Basin (Wells and Moss, 1983). The Amadeus Basin is an east-west trending intracratonic depression of about 800 km length, bounded on the north and south by the Arunta and Musgrave Blocks, respectively. It also contains Late Proterozoic and Palaeozoic sediments that reach a maximum thickness in the northern part of the basin of 14 km; south of the Gardiner Fault (Fig. l), the sedimentary cover in the southem platform region of the basin is much thinner (Wells et al., 1970; Lindsay and Korsch, 1989).

DEEP

SEISMIC

PROFILING

IN CENTRAL

Some of the largest any where

continent

gravity

present

the total variation

Generally, occur

are

the most

near

anomalies

in central is about

negative

the basin

249

AUSTRALIA

margins

seen on Australia,

1400 pm s-‘.

Bouguer while

anomalies the positive

solely stretching the basins northern

and southwestern

Australian

of the gravity

The

field in central

and

Wellman

Australia

and Shaw (1973)

(1978).

Basins have a complex

were de-

tive model

profiles

and

Ngalia

eation

over a

the deep crust, the mapping

evolutionary

history

basin

margins

of changes

of major

help

in crustal

The are also

Models in the

for the central

by Teyssier

(1985)

(1987)

may

locations

period of crustal compression, during which time the crust buckled to form the depocentres and significant developed

seismic

Shaw

(1976)

long period of time (c. 600 Ma). A mechanical model by Lambeck (1983) invokes a protracted

basement

and

because

equilibrium.

region were devised

(thin-skinned)

Mathur

The Amadeus

mechanisms,

in isostatic

characterised by thrust structures. style of crustal deformation

anomalies correspond to the Arunta and Musgrave Blocks. Models of the crust to explain the features vised by Anfiloff

or thermal

are not

(thick-skinned). to constrain

thickness,

faults or detachment

the

the delin-

surfaces

of sedimentary

into thick-

nesses throughout the basins, and the overall geometry of the basins. These features will assist in discriminating between evolutionary models of the central

Australian

region.

highs. A revised model that still invokes periods of compressional tectonics was by Lambeck et al. (1988). An alternaby Lindsay

and

Korsch

(1989)

pro-

poses a complex history involving both extensional and compressional mechanisms. The evolution of the region cannot be satisfactorily explained by models of basin formation involving

Results from near-vertical incidence profiling Northern

and Central Arunta

Provinces

The main features inferred from the stacked seismic sections are shown with the gravity profile in Fig. 2. Figure 3 is a migrated version of Fig. 2,

s

N

AMADEUS

BASIN

I

ARUNTA BLOCK

1j)Okm

Fig. 2. Line diagram of main north-south

reflection line Ll (Fig. 1) with the observed gravity profile. Regions of prominent

reflections have been marked by thicker lines, and shading denotes zones of strong reflected energy. Vertical exaggeration is 2 an average velocity of 6.0 km s-‘.

MN, GH and EF show locations of seismic sections of Figs. 4 and 5.

: 1 for

250 AMADEUS Southern

S

SI

G

Reg,on

N

N

M

Missionary

BASIN

Plattorm

ARUNTA Redbsnk

Plain “1

BLOCK Ngalla Basin

n

E

N

40km

Fig. 3. Line diagram of Fig. 2 migrated with a constant velocity of 6.0 km s-‘. Vertical exaggeration is 2 : 1. MN, GH and El” show locations of seismic sections of Figs. 4 and 5.

assuming a constant seismic velocity of 6.0 km s-‘. The band of northerly dippixtg reflections at tW between 2 and 10 s beneath the Northern Ar~ta _Province is ~~~1~~~ strik&g (Figs. 2 and 3). -These reflections dip 20-W W probably coqnd to a series of fax& surfaces. This interpretation is consistent with the pattern of dipping faults within the Arunta Block inferred from the surfp geology. Further south, the strength of the r&Iections diminishes soznewhat in the granulites of the Central Arunta Province, though the ap-

parent northerly dip of the reflections contiitues. The most significant boundary of the entire profile is the RDZ which is &x&y i asaplausar feature to depths of at least 30 km, ihe m&ted dip is about 35-40”. Southern Arunta Province and Northern Awwdms Basin To the south of the RDZ, the feflectioa character is quite different. The persistent, steep,

DEEP SEISMIC

PROFILING

IN CENTRAL

AUSTRALIA

COP

Fig. 4. Seismic sections Southern

recorded

Arunta

in the northern

Province

part of the Amadeus

(B) corresponding

northerly apparent dip of the observed absent, and the section contains strong

signals is sub-hori-

zontal bands of reflected energy at times greater than 6 s. Figure 4B shows prominent deep reflections within 21-30

the Southern

Arunta

km) that are also observed

Basin (A) corresponding

to EF of Figs. 2 and 3. The gap between

Province at earlier

(depths times

on the parallel profile (L2 of Fig. 1) to the east, so that there is a small westerly component of dip as well as the northerly component evident in Fig. 4B. Figure 4A shows the seismic section at the northern edge of the Amadeus Basin, where the sedimentary section is more than 10 km thick. The lowermost part of the Proterozoic sequence gives rise to the discontinuous reflection segments at times greater than 3.2 s, and the uppermost basement boundary is not clearly defined. The reflections die out at the northern end of Fig. 4A, close to where surface geological observations show that the sedimentary rocks have been folded upwards. The deep section of Fig. 4B has a layered character similar to sections observed in some other Proterozoic areas, such as the Siljan impact structure in Sweden (Dahl-Jensen et al., 1987); drilling in the Siljan area has shown the reflectors to be mafic sills (Juhlin, 1990). Sills of mafic rocks or alternating layers of mafic and felsic rocks provide an acceptable explanation of the deep reflections observed below the Southern Arunta Province. The youngest intrusions observed in the surface geology of the Southern Arunta Province

to GH in Figs. 2 and 3, and in the the sections

is about

20 km.

are the Stuart Dyke Swarms (south and east of L2 of Fig. I), of doleritic composition, and dated at about 900 Ma (Black et al., 1980). They pre-date the youngest sedimentary rocks of the Amadeus Basin. However, rocks of sedimentary origin could also explain the large reflection coefficients. Is it possible that the deep reflections of Pig. 4B are from

rocks

that

were

originally

part

of

the

Amadeus Basin, in which case they would delineate a major overthrust? Or could the reflectors represent deep crustai shear zones? The latter explanation appears unlikely because of the relatively high reflection amplitudes and the thickness (about 10 km) of the reflecting region, but cannot be dismissed entirely (see Warner, ‘1990). Reprocessing of the data at the northern margin of the Amadeus Basin may provide clues by enabling clearer imaging of some faults. Southern platform

Strong

region of the Amadeu.v Basin

reflections

are observed

throughout

the

sedimentary rocks of the northern part of the Amadeus Basin (Figs. 2 and 3). A vertical uplift of the southern block of about 5 km is inferred along the Gardiner Fault from the seismic sections. Reflections from the sedimentary section together with some multiples remain clear for a distance of 40 km south of the Gardiner Fault. However, further south within the southern platform region,

and the bands of deep basement reflectrons are almost a mirror image of the northerly dipping bands of deep reflections observed below the Southern Arunta Province (Fig. 4) and the fainter reflections

associated

with the Ormiston

Nappe

and Thrust Zone (Goleby et al., 1990). The similarity of the style of basement the southern Amadeus

reflectivity

below

Basin to that below the

Southern Arunta Province suggests that the basement from south of the RDZ margin

of the Amadeus

Basin

to the southern forms

a single

tectonic province. The base of the crust, usually defined as the transition to a lower non-reflective region, is not clearly discernible along the profile, though a crustal thickness of 35-40 km appears reasonable below the Northern Arunta Province (Goleby et al., 1990). Fig. 5. Seismic section Basin, 5.5-6.2

showing

strong

s (MN southerly

from the southern bands

of Figs. dipping

part of the Amadeus

of reflected

2 and

energy

3). Note

thrust marked

also

starting

at

the possihle

by arrows.

shallow reflections become diffuse, and there are few clear reflections from the deep crust. The absence of strong shallow reflections continues to the southern end of the profile; the sedimentary cover is often less than 2.5 km thick throughout the southernmost

150 km. Variable

thicknesses contribute

Other seismic profiling

weathering

to the poor record quality,

but reprocessing with improved statics corrections has resulted in better resolution of some reflections.

Seismic refraction profiies The refraction survey recorded to offsets of 350 km in 1985 and extended to 500 km in 1988 (Fig. 1) showed no Pn arrivals (Wright et al., 1987; Goleby et al., 1988). Several branches of later arrivals (Fig. 6) can be interpreted as possible wide-angle reflections from the crust-mantle boundary (PmP), suggesting an average crustal thickness of at least 50 km for the region of the Southern

Arunta

Province

that has been thrust

below the Central Arunta Province (Fig. 2). Seismic refraction data recorded across the north-

Strong reflections similar in appearance to those observed beneath the Southern Arunta Province occur at times between 5 and 10 s below the southern part of the southern platform region (MN of Figs. 2 and 3; Fig. 5). There is an apparent dip to the south, and the onset of these bands of reflections is sharp over a distance of more than 40 km. Figure 5 also shows a planar, southerly dipping feature with an apparent dip of about 20” that is interpreted as a thrust fault; at

Expanding reflection spreads and three-dimensional refraction profiling

times greater than 2 s, the observed energy is reflected from within basement. South of the present seismic profile, in the Musgrave Block, the existence of southerly dipping thrusts is well established from geological evidence (Collerson et al., 1972). The southerly dip of the inferred thrust

Expanding reflection spreads were recorded in the Arunta Block and northern part of the Amadeus Basin (Fig. 1; Wright et al., 1990). The Amadeus Basin expanding spread yields a detailed average velocity model for the basin sedimentary

ern part of the Amadeus Basin (Fig. 1) also indicate a crustal thickness in excess of 50 km. An intra-crustal increase in seismic velocities from 6.2 to about 7.0 km s- * occurs at 40 km depth below the Amadeus Basin, in contrast to 30 km within the Southern Arunta Province.

DFFP

SFISMIC

PROFTI.ING

IN CENTRAL

253

AUSTRALIA

ARUNTA

BLOCK REFRACTION

TRAVERSE

w

AMADEUS

BASIN

Oastance

Fig. 6. Seismic refraction

sections,

Arunta

Block and Amadeus travel-time

REFRACTION

(km)

Basin. Numbers branches

rocks that shows two pronounced low-velocity layers (Fig. 7); its main function is to assist studies of basin evolution by providing reliable seismic velocity estimates at depths below 3 km, where velocity resolution from both industry and BMR seismic reflection profiling is poor (Wright et al.,

TRAVERSE

in km s

on sections

represent

apparent

velocities

of identified

‘.

et al., 1988; Greenhalgh et al., 1990b). The refracted arrivals recorded by the remote instruments, after reduction by a tomographic inversion technique, show significant lateral heterogeneity in the crystalline rocks of the Central Arunta Pro-

1990). A geological interpretation of Fig. 7 is given by Wright et al. (1989). While the two expanding spreads were being recorded in the Arunta Block, remote seismic recorders were deployed on the line orthogonal to

vince (Greenhalgh et al., 1990b). Superimposed on this lateral heterogeneity is about 7% anisotropy (Fig. 8) attributed mainly to propagation through strongly foliated granulites formed at depths below 25 km and thrust up to the earth’s surface; the direction of maximum velocity (east-west) coin-

the one with the shots and reflection spread to give three-dimensional refraction coverage (Goleby

cides with the dominant direction of foliation inferred from geological studies in nearby outcrop

254

4.5

R.m.5.

Velouty (km;s) 5.0

5.5

(Glikson, 1987; Greenhalgh et al., 1990a). The expanding spreads recorded within the Arunta Block also indicate a region of increased reflectivity between depths of about 27 and 35 km with seismic velocities in excess of 7 km s-’ (Wright et al., 1990); this is in good agreement with the refraction results of Fig. 6.

6.0

veicciti

Condusious

Fig. 7. Root mean square (r.m.s.) velocity measurements (dots) with standard errors for sedimentary rocks of the Amadeus Basin. IntervaI vehxities have been computed from the smooth curve (cubic spbne) fitted through the r.m.s. velocity terms. A, B, C and D refer to prominent reflections on the seismic section that were used to define dip and moveout corrections for r.m.s. velocity measurements (Wright et al., 1989). Numbers on the right are approximate depths of reflrztions.

Persistent northerly dipping events within the Northern and Central Arunta Provinces are best explained as reflections from faults. Strong reflections within the Southern Arunta Province and the southern part of the Amadeus Basin are produced at depths between 18 and 30 km and have a layered character. The RDZ forms the most fundamental boundary of the survey region and is interpreted as a planar feature extending to depths of at least 30 km. Crustal thickness exceeds 50 km beneath the northern part of the Amadeus Basin and the Southern Arunta Province. It appears to decrease to 35-40 km below the Central Arunta Province. The reflection profiles support a thickskinned model of the tectonic evolution of the central Australian region (Shaw, 1987; Goleby et al., 1990), and suggest a present crust-mantle configuration that agrees best with that proposed by Lambeck et al. (1988). Experimental profiling

5 0

90

270

180 Azimuth

360

(deg)

Fig. 8. Seismic velocity versus azimuth for gram&e facies rocks of the Neutral Arunta Province, showing about 7%anisotropy.

DEEP

SEISMIC

yields

PROFILING

detailed

IN CENTRAL

information

the granulites

at shallow

of the Central

Arunta

on the three-dimensional

structure

An expanding

spread

northern thick

reflection

part of the Amadeus

constrained stratigraphic

on and

of the RDZ. recorded

throughout

sequence,

studies

depths

Province

in the

Basin provides

seismic vefocities

sedimentary

255

AUSTRALIA

that

of basin

well

the 9 km

are

useful

in

Arunta

Block,

evolution.

Greenhalgh,

S.A., Sugiharto,

1990b. Tomographic ity variations J.H.

B.L.N. and

Kennett

References

Symp.

Earth’s

in Position. Black,

Sydney

L.P., Shaw,

Stuart

Dyke

Australian

Sydney,

shield

(Editors),

Field and Secular

University,

Variations

pp. 273-289.

D.M.

Leven.

B.L.N.

nents

and its bearing

sedimentation

on the onset

in central

of late

Australia.

J. Geol.

R.W.R.,

1972. An

Sot. Aust., 27: 151-155. Collerson,

K.D.,

example

R.L. and Rutland,

of structural

Musgrave Aust..

Oliver,

Orogenic

and metamorphic Belt, central

relationships

Australia.

in the

J. Geol.

Sot.

18: 379-393.

Dahl-Jensen,

T..

D.,

Juhlin,

Pedersen,

L.B., 1987. Deep reflection

cambrian

of Sweden.

Geophys.

C.,

Palm,

seismics

H.

and

in the Pre-

J. R. Astron.

Sot.,

89:

371-37s. Glikson,

1987. Regional

Redbank-Mount Arunta Goleby,

and evolution

of the

Zeil thrust zone: a major lineament

in the

Inlier, central

phys..

structure

Australia.

BMR J. Aust. Geol. Geo-

10: 89-107.

K.,

B.R., Wright,

C., Collins,

Block and the Ngalia

Earth Goleby.

C.D.N.

and Kennett,

and refraction

profiling

and Amadeus

B.L.N.,

across

the

Basins. Aust. J.

Sci., 35: 275-294. B.R., Kennett.

Lambeck,

Astron.

terozoic testing

B.L.N.,

Arunta models

Block,

central

of tectonic

Finlayson,

C. Wright,

(Editors),

Seismic Probing

Tectonophysics, Greenhalgh,

Wright,

C., Shaw,

199Oa. Seismic

anisotropy

R.D.

and

of Continents

and

in the Pro-

processing

In: J.H. Leven,

Dooley

173: 257-268

S.A., Sugiharto,

Australia:

evolution.

J.C.

profiling

B.L.N.

for D.M.

1983.

in granulite

Probing

of Continents

173:

63-72

(this

time

J.C. Dooley

Probing

of Conti-

1’73: 345-360

evolution

Australia.

J.F. and

and

of

the

Geophys.

Korsch,

the intracratonic

R.D.,

crustal

J. R. Astron. R.J.,

and sea level changes

in-

J. R.

1988. Teleseismit

structun:

in central

Sot., 94: 105-124.

1989. Interplay

in basin evolution:

Amadeus

Basin,

central

of dynamics

an example

from

Australia.

Basin

Res. (in press). Mathur,

S., 1976. Relation

Aust. Geol. Geophys., Shaw,

of Bouguer

in southwestern

R.D.,

Central

1987. Basement

versity, Canberra,

A.C.T.

R.D.,

Inlier:

Stewart.

2. Tectonic

Uplift

ensialic

history.

Warner,

Aust. J. Earth thrust

system

in an intracratonic

M., 1990. Basalts,

water

or shear

D.M.

Finlayson,

and B.L.N.

Continents 163-174 Wellman,

and

Kennett their

7: 689- 700.

(Editors),

Margins.

zones in the lower C. Wright, Seismic

of 173:

(this volume). P., 1978. Gravity

blocks.

density

evidence

for abrupt

at the junction

stratigraphy

3: 153 -162.

structure.

D.J., Ranford,

of the Amadeus

Bur. Miner.

Resour.

C., Goleby,

Basin, Northern

Aust.

Bur.

Miner.

and

L.C. and Cook, P.J., 1970. central

Australia.

Aust.

Bull., 100: 222~~. Greenhalgh, experiment.

J. R. Astron.

C., Barton.

Basin.

B.R.. Collins.

seismic

Geophys.

in

crustal

Bull., 212, 88 pp.

Wells, A.T., Forman, Geology

and

changes

of Australian

BMR J. Aust. Geoi. Geophys..

Territory:

Wright,

J.C.

Probing

Tectonophysics,

Wells, A.T. and Moss, F.J., 1983. The Ngalia

Wright.

Australia.

Sci.. 31: 457-484.

Geol.,

Leven,

Uni-

L.P., 1984. The Arunta

J. Struct.

In: J.H.

J. in

National

belt in cent-al

environment.

crust?

BMR

Subsidence

Australian

mobile

C., 1985. A crustal

tectonic

and Basin

thesis.

A.J. and Black,

a complex

to crustal

Australia.

1: 277-286.

Ph.D.

Shaw,

anomalies

and central

Australia.

Australian

of the

and

G. and Shaw,

Geophys.

and their Margins.

facies rocks

Seismic

Structure

anomalies

S.

B.R.,

borehole.

C. Wright,

Sac., 74: 843-866.

Sugiharto.

C. and Goieby.

in the Siljan

Tectonophysics,

of central

Kennett

(this volume).

S., Wright,

Finlayson. (Editors),

K., Burgess,

Resour.

K., 1990. Seismic reflection

In: and

from the Gravberg-1

Margins.

basins

mean crustal

1988. Seismic reflection Arunta

their

tracratonic

Dooley

A.Y.,

Australia.

(this volume) Lambeck,

Teyssier.

Dyrelius,

Kennett

and

structure

R.D. and Offe, L.A., 1980. The age of the

Swarm

Precambrian

effects of three

and P.V. Angus-Leppan

Gravity

veloc-

J.C. Dooley

of the reflections

In: J.H.

Australia.

In: R.S. Mather

Proc.

Seismic

B.R.,

crustal

central

Tectonophysics.

on results

Lindsay,

areas.

C. and Goleby,

C. Wright,

C., 1990. Interpretation

travel

blocks in separate

to: Geophys.

of upper

Block,

(Editors),

Margins.

Ring area based

Lambeck.

granulite

S., Wright,

D.M. Finlayson,

their

Juhlin,

We thank B. Drummond and D. Finlayson for critically reading the manuscript. This paper is published with the permission of the Director, Bureau of Mineral Resources.

large uplifted

Submitted

reconstruction

in the Arunta

Leven,

and

W. and Shaw, R.D., 1973. The gravity

Australia.

volume).

Acknowledgements

Anfiloff,

central

Res. Lett.

C.D.N.. S., 1985:

Kermett, 1987.

The

preliminary

B.L.N., central results.

Sot., 89: 431-436.

T.. Goleby,

Seismic velocity variations

B.R. and Taylor,

in the Northern

F.J.,

Amadeus

1989. Basin,

central

Australia.

file. Explor. Wright,

from an expanding

Geophys.,

C., Barton,

T., Goleby,

D., 1990. The interpretation profiles:

examples

spread

reflection

pro-

20 (in press).

J.H.

Leven.

B.L.N.

B.R., Spence, A.G. and Pfister.

and

of expanding

volume).

from central

spread

and eastern

reflection

Australia.

In

D.M.

Kennett their

Finlayson.

(Editors),

Margins.

C. Wright, Seismic

Tectonophysics,

J.C

Probing 173:

Dooley

dnd

of (I ontinents 73--X2

(this