The mid-crustal horizon under the Eromanga Basin, eastern Australia

Tectonoph.wics, 100 (1983) 199-214 Elsevier Science Publishers

199

B.V., Amsterdam

THE MID-CRUSTAL

- Printed

in The Netherlands

HORIZON UNDER THE EROMANGA BASIN, EASTERN

AUSTRALIA

D.M. FINLAYSON Bureau of Mineral Resources, Geology and Geophysics, Canberra, A. C. T (Australia) (Received

by Publisher

September

26, 1983)

ABSTRACT

Finlayson,

D.M.,

Friedman

1983. The mid-crustal

horizon

and M.N. Toksbz (Editors),

under

the Eromanga

Continental

Tectonics:

indicate

that a major

Basin, eastern

Structure,

Australia.

Kinematics

In: M.

and Dynamics.

Tectonophysics, 100: 199-214.

Long-line

explosion

seismic

exists under the Eromanga provinces.

The velocity

boundary

increase

is shown

of a zone of discontinuous

increase

of 0.35-0.6

gradient

produces

km/s

continental

Australia,

The velocity

boundary

between

occurs

conspicuous

The seismic data present detail.

recordings

Basin which contrasts

mid-crustal

the crust of this region

to be a regional

seismic reflections

feature

and

characteristic

wide-angle

reflections

evidence

a feature not prominent in the lower crust

at distances

greater

to date of the existence in other cratonic

below

the horizon

to correspond

increase tectonic

to the upper The velocity

depth of 24 km. This velocity than 60 km from the shot point.

of a major mid-crustal

provinces

is 6.7-7.0

velocity

of the lower crust.

over a small depth range at an average

the clearest

P-wave

from its neighbouring

horizon

which have been investigated km/s.

the upper and lower crust which could imply a different

The horizon

tectonic

history

in in

represents

a

for these two

zones.

INTRODUCTION

On a world scalar anomaly Australia contrasts

stands

map of Magsat

out as a prominent

with its neighbouring

tectonic

data, the Eromanga

magnetic provinces.

anomaly

Basin in eastern

low (Frey,

A large proportion

1982) which of the Earth’s

crust must be involved in producing this anomaly. Using a magnetite Curie point of 670°C and the Sass and Lachenbruch (1979) geotherms for central and eastern Australia, a Curie point depth of 35-40 km is appropriate for the Eromanga Basin and surrounding region. Thus we have at least one geophysical parameter which strongly suggests that the Earth’s crust under Eromanga Basin is significantly different from that of surrounding regions of continental Australia. In 1980 the Bureau of Mineral Resources, Geology and Geophysics (BMR) conducted a long-line seismic refraction survey and coincident vertical seismic

THARGOMINDAH QUiLPlE TROUGH

SHELF

0

100

,

I

I

I

A-Terebooka

E- Blackall

B-Taltyabra

F-Adavale

C-Cheeple

G-Toompine

profiles.

-

200,Km I

&

I

I

Shot point

2S/O/ll2

Recordmg line

Ii-Thargomindah

D-Barcaldine

Fig. 1. General

I

l

!3iELF

geology

Eromanga

of the central

Basin sediments

Eromanga

Basin and the location

of long-line

seismic refraction

overlie the whole of the region.

profiling to 20 s in the central Eromanga Basin region (Fig. 1). Finlayson et al. (1983) have already reported some results from the refraction work along the 300 km east-west traverse and summa~sed the major geological features of the region. Mathur (1983) has highlighted the significant features of the deep vertical profiling records. A major feature of the velocity/depth dist~bution from the east-west data is the prominent mid-crustal horizon at a depth of 21-24 km where the P-wave

EAST

WEST

EROMAWGA

COOPER

L.PAlAEOZOIC PRE-CAMBRIAN

I

GALILEE

I

BASEMENT

I I

I

I i

26/O/113 Fig. 2. The Eromanga

Basin and in&a-basins.

velocity increases by up to 0.6 km/s in a depth range of less than 0.5 km. This is interpreted from large-amplitude wide-angle reflection phases beyond the critical distance. During 1981 BMR conducted further long-line seismic refraction recording on a north-south azimuth traversing the Adavale Basin, Quilpie Trough and Thargomindah Shelf (Fig. 1). Figure 2 is a simplified stratigraphic diagram of the Eromanga Basin and its underlying basins. This paper presents interpretations of data from this traverse and provides further evidence for a mid-crustal seismic horizon as a general feature of the crust under the Eromanga Basin and discusses its significance for theories on the tectonic evolution of the region. THE MIDDLE

CRUST

Seismic models of the Earth’s continental crust have long recognised the necessity of including some form of increase in the P-wave seismic velocity with depth in order to satisfy observed data (e.g. see Bott, 1971). Such models often include the concept of upper and lower crustal layers separated by a Conrad discontinuity at which the velocity increased. Explosion seismic work during 1950-1970 indicated that such simple models were not appropriate and more complex velocity/depth distributions were required to satisfy the observed data (for reviews see Gloss, 1969; Sollogub, 1969; Kosminskaya

202

et

al., 1969; Healy and Warren,

tinuity

changed

extreme

there

were places

continuous

velocity

Landisman

(1966) pointed

depths

1969). The concept

to one of many

possible

where

increases

velocity

no layering

with depth

Landisman Liebscher

further

including a Conrad discontinuity depth. However, the widespread continents

evidence evidence

in the crust.

was evident

and

to satisfy data. Mueller

the crust

and

zones were likely in the crust at

included

by Doyle et al. (1959) to substantiate

(1962) to illustrate

At the

within

out that low velocity

(1966) also used statistical

discon-

were enough

less than 20 km. In fact, these authors

ern Australia

of a single mid-crustal gradients

observations

from southeast-

their interpretations. from deep vertical for horizons

Mueller and soundings

throughout

by

the crust,

at 7 s two-way reflection time i.e. at about 21 km existence of a Conrad discontinuity throughout all

was rightly questioned.

In Australia more complex

recent detailed crustal features

investigations of continental structure resulted being recognised. Figure 3 illustrates examples

in of

26/O/154 Fig. 3. Velocity/depth mond,

profiles

1983); 2 -McArthur

Australian ern La&an homogeneity.

Craton Fold

(Finlayson,

from other

Basin, North

regions Australian

1982); 4 -southern

Belt (Finlayson

and

McCracken,

of continental Craton Lachlan

Australia.

(Collins,

I -Pilbara

1983); S -Tennant

Fold Belt (Finlayson

1981). All models

Block (DrumCreek, North

et al., 1979); 5-north-

were derived

assuming

lateral

203

velocity/depth

models from the Phanerozoic

(Finlayson

et al.,

Australian

Craton

(Drummond,

Finlayson

(Finlayson,

throughout

Australia

there

significance

changed also. The models of continental by the geochemistry of rocks comprising

1981),

by velocity

Australia

Proterozoic

1983) and Archaean

depths (Finlayson,

mid-crustal horizon. In recent years the tectonic

Fold Belt in southeast

McCracken,

are characterised

at mid-crustal

geology

Lachlan

and

1982; Collins,

1983). All models

“discontinuities” basement

1979;

Pilbara

gradients

North Craton

rather

than

1979). Thus in regions of exposed does

not

appear

of mid-crustal

to be a major

seismic

horizons

has

crustal structure have long been constrained the continental lithosphere (see for example

McLennan and Taylor, 1982; Ringwood, 1982). However, the introduction of long, deep-seismic, reflection profiles in continental U.S.A. has highlighted the possibility of large scale decollement of kilometers in extent example

Cook et al., 1979; Harris

continental tional

and mylonite horizons in the middle crust many hundreds resulting from horizontal tectonic movements (see for

mid-crustal

or metamorphic

and Bayer, 1979; Smithson

horizons

may not only be interpreted

horizons

resulting

but also in terms of large scale extension

SEISMIC

REFRACTION

The locations

from vertical

et al., 1980). Hence in terms of composi-

geochemical

and shortening

differentiation

of the lithosphere.

PROFILES

of seismic refraction

profiles used in this paper are shown in Fig. 1.

The east-west traverse extends from the Cooper Basin across the Warrabin Canaway Ridge, Quilpie Trough and Cheepie Shelf. The north-south extends

along

Thargomindah

the

axis

of the Adavale

160 km will be discussed. reversed,

Basin

and

Shelf. In this paper only the recorded the east-west

Trough

on

to the

seismic data out to distances line

will be considered

of

as two

B-C, and the central part of the north-south as two reversed, 160 km traverses E-F and F-G. A full

160 km traverses

line will be considered

Hence

Quilpie

Trough, traverse

A-B

and

description of survey operations has been written by Lock (1983). The shots for the interpretation in this paper were, respectively, 0.7 t and 0.9 t on the east-west

and north-south

m depth in drillhole

patterns,

lines. DuPont usually

Anzite Blue explosive

100 kg of explosive

fired electrically and timed with respect broadcast by VNG. Seismic recordings

was placed at 40

per hole. The shots were

to the Telecom Australia radio time signal were made at 7.5 km intervals on BMR

automatic seismic tape recording systems, 21 of which were used on this survey. These systems record both a high and a low-grain vertical seismic channel (24 dB separation, frequency modulated), a programmable crystal clock time-code and the VNG radio time signal to ensure a common time source for all data (Finlayson and Collins, 1980).

204

SEISMIC RECORD SECTIONS

Seismic recordings

were digitized

using the playback

Seers (1982). The seismic record sections have the traces normalized

to the maximum

all have been filtered in the bandpass channel channel channel.

produced

2-15

system described

by Liu and

from the data for this paper all

amplitude

on each individual

trace and

Hz. In many cases the low-gain

seismic

displayed the character of the seismic phases better than the high-gain because of overmodulation of the large amplitude phases on the high-gain Consequently the majority of traces displayed on the record sections are

from the low-gain channel. The high-gain channel has, however, been used to determine the arrival times of the various phases, often with an error of less than 0.05 s; these are indicated The diagnostic been outlined

features

of a major velocity

boundary

at mid-crustal

depths

have

by Bott (1971) and Braile and Smith (1975). These are principally

large amplitudes the apparent

expected

velocities

A-B-C

for super-critically

of the refracted

crust and the identification TRAVERSE

by dots on the record sections.

of refracted

reflected

and reflected

energy

phases

the

from the boundary,

from within

the upper

phases from the lower crust.

(EAST-WEST)

Data from the traverse A-B-C (1983); only the essential

features

have already

been described

of the mid-crustal

horizon

by Finlayson

will be described

et al. here.

Fig. 4 shows the seismic record sections along the two halves of the traverse in the distance range 40-160 km. They clearly illustrate seismic phases interpreted as traversing the upper and middle crust. The series of first arrivais out to distances of about 100 km (labelled p-q) are usually impulsive and have an apparent velocity of less than 6.1 km/s. basement

beneath

The other

They are identified the sedimentary

significant

phases

with P-waves

traversing

the upper

crustal

sequence. displayed

in the record

sections

are the events

labelled T--S. In Figs. 4a, b and c they are evident at distances greater than 60 km. Near point “r” the apparent velocity is greater than 6.5 km/s and near point “3” it approaches velocity

that of the upper crustal basement

of the critically

refracted

i.e. about 6.1 km/s. The low apparent precludes their being upper mantle events “r-t”

arrivals. These large amplitude from a prominent mid-crustal

events are interpreted as being wide-angle reflections velocity increase. In Fig. 4d the events labelled X--Y

have a much higher apparent

velocity

than events r-s and Finlayson

_-----Fig. 4. Seismic record sections from the east-west traverse A- B-C.

et al. (1983)

_____-._. a. Shots at A recorded to B. b. Shot

at B recorded to A. c. Shots at C recorded to B. d. Shot at B recorded to c. Seismic traces have been normalised to equal maximum amplitude and filtered in the bandpass 2-15

Hz. Dots indicate first

arrivals confidently read from high-gain records (not all shown). The various seismic phases are described in the text.

205

01

I

I

I

I

60

40

I

I

I

I

L

I

1

I

160

I

J

I

160

120

80

80

160

120

60

01 40

-I

I

120

I

MSlAtJCE ( 0) km

I

J 160

t

120 26/O/115

206

0

Y

“, r

0

Fig. 5. Seismic record Shot at F recorded annotation

sections

from the north-south

to E. c. Shot at F recorded

the same as in Fig. 4.

traverse

E-F-G.

a. Shots at E recorded

to G. d. Shots at G recorded

to F. Trace

to F. b.

display

and

207

have indicated that they result from a shallower crust/mantle boundary under the Canaway Ridge where the crustal velocity/depth distribution is significantly different from the surrounding region. TRAVERSE

E-F-G

(NORTH-SOUTH)

The traverse E-F-G was designed to extend the regional coverage of crustal investigations to ensure that features found on the east-west traverse were not isolated features. Figures 5a, b, c and d show the seismic record sections in the distance range 40-160 km from the central part of the north-south traverse. Traverse E-F (Figs. 5a and b) is centrally placed in the Adavale Basin. The features seen on the east-west traverse are again evident on this north-south traverse. Arrivals p-q have apparent velocities of less than 6.1 km/s and arrivals r--s have a similar character to wide-angle reflections from the mid-crustal horizon on the east-west traverse. This interpretation is therefore attached to the r-s events on the north-south traverse. Traverse F-G (Figs. SC and d) crosses from the Adavale Basin and Quilpie Trough onto the ~argonindah Shelf. The difference in thickness of low-velocity basin sediments under shot points F and G is an obvious feature of the record sections, the first arrivals at distances out to 60 km being 0.8-0.9 s earlier from shot point G. However, this difference between the thickness of basin and shelf sediments can be taken into account in any interpretation. The principal feature of the record sections beyond 40 km is still the series of wide-angle reflections from a horizon in the middle crust. VELOCITY/DEPTH

MODELS

Finlayson et al. (1983) have derived velocity/depth models for the traverse The travel-time curves for these models are superimposed on the record sections in Figs. 4a, b, c, and d. The models themselves are shown in Fig. 6. The interpretation of the record sections from the north-south traverse E-F-G was conducted in a manner similar to that for the east-west traverse. The travel-time curves from the preferred modeis are superimposed on Figs. 5a, b, c and d. These models are also shown in Fig. 6. One feature of the models different for the north-south line compared with those for the east-west line is the lack of a reduction in velocity in the upper crust at depths of 5-12 km. The models shown in Fig. 6 indicate that there is no decrease in velocity in the approximate depth range 12-22 km and it is possible that the sharp velocity reduction on the models from the east-west line should not be taken as a significant feature. Certainly, if the velocity reduction in Fig. 6 model 3 was reduced, the depth to the mid-crustal horizon would increase and be more in accord with the average depth of 24 km for this horizon. A-3-C.

I

I

I

I

I

I

209

VERTICAL

SEISMIC REFLECTION

PROFILING

As mentioned in the introduction, extensive seismic reflection work was also conducted in the central Eromanga Basin. Approximately 1500 km of six-fold CDP shooting was recorded to 20 s two-way reflection time. Mathur (1983) has described some of the deep reflection recording results from the central part of the east-west traverse A-B-C. Below the sedimentary sequence there is a zone of very few reflections until a two-way reflection time of about 8 s is reached. Between 8 and 12.5 s there is a broad zone of numerous short, discontinuous reflection events which model studies (Fuchs, 1969) have shown can be produced by laminae of alternating high and low velocity the layer thicknesses being less than the seismic wavelength of about 100 m. The mid-crustal horizon interpreted from the long-line refraction work described in this paper corresponds with the start of the prominent reflection events in the middle crust. Under the north-south traverse E-F-G the same zonation can be applied to the reflection events. The zone of reflection events is in the two-way-time interval 8-14 s (S.P. Mathur, pers. commun., 1983). The velocity/depth models in Fig. 6 are compatible with the vertical reflections at 9 s. DISCUSSION

The seismic record sections in Figs. 4 and 5 present the clearest evidence to date of the existence of a major mid-crustal velocity increase in continental Australia. The data from both east-west and north-south traverses show that this feature is not an isolated structure but is general throughout the central Eromanga Basin. The only exceptional structure is that under the Canaway Ridge from shot point B shooting eastwards which results from a different tectonic environment under the ridge. The mid-crustal horizon does, however, generally seem to be present under both basin and shelf areas. The velocity increase at this horizon is interpreted as being in the range 0.35-0.6 km/s and its depth being in the range 21-25 km, however, the average depth is about 24 km. In Fig. 7 the refraction and reflection information have been combined to produce a schematic representation of the Earth’s crust in the central Eromanga Basin. The deep velocity structure has been taken from the inte~retation of Finlayson (1983). It includes a crust-mantle boundary at a depth of 36-41 km with a velocity in the upper mantle of 8.15 km/s. Deeper within the upper mantle at a depth of 56-57 km there is another seismic horizon where the velocity increases to 8.35 km/s. A low velocity zone is interpreted above this horizon. The vertical reflections apparent in the lower crust cut out at the crust/mantle boundary and within the upper mantle there are no further reflections (Mathur, 1983). The tectonic significance of the mid-crustal horizon in the Eromanga Basin is difficult to determine. Such prominent horizons are by no means always recorded in

continental

regions.

tion records

In some areas of Europe

are associated

discontinuities

particular

with “discontinuities”

of Dohr and Meissner

horizons

evident

e.g. the Conrad

on reflec-

and Subconrad

(1975). and not with broad

zones of reflec-

tions. Under

the Columbia

Prodehl

Plateau

and Basin and Range

(1970, 1977) identified

profiles with retrograde velocity

increases

his “h”

branches

and “a-h”

of the travel-time

at mid-crustal

depths.

Province

events

of western

on long-line

curve originating

However,

the events

U.S.A.

refraction

at fairly strong

are not ubiquitous.

Prodehl (1970) for example, interpreted a distinct lower crustal layer with the velocity increasing from 6.446.6 km/s to 7.0 km/s under the northern Basin and Range province but not in the southern part. Braile (1977) and Muller and Mueller (1979) have shown how in another parts of the Basin and Range Province (eastern) there is a thin crust (30 km) with the lower crustal velocity only reaching 6.4-6.6 km/s and the dominant mid-crustal reflections come from a velocity increase at about

lo-12

km depth, below a low velocity WARRABIN

CANAWAY

--_=_-z=s~-_-~~__

zone. P-WAVE

DUILPIE

VELOCITY

(kds)

-______-

~~

_I.

-\*

_

‘.

I

\,

t

.,

,‘

_

--~-

.

7,: ;* , : :. : , *,.:., .* . . .;. ‘. . .: , 1.” ._..I. .I

1.:.

.

. /.,..

:..._. *I ,,:. ‘1 . (. _I. ..

’ ’

L

c

;.. .

.,‘_**‘. . ..‘.i’

-. ‘c*‘>‘_‘,

‘\--‘,

,_I.

\ -e I ,-;, -7 > ’

.= e ,:-** .T-_ 7,’ I .*. *. nl,‘, ,. :.a . _.. , * . : .,. ’ ,. .*.*... *‘. c c. ., _, ,. .:. . . ,’ .. . . ,.‘:. ..:. * . .: ‘, . , . * >. . . . . . , . . a. . . * .I,, :,: ..‘,. ,...*.“.;,::: .:. ‘*. a, ., .‘;. . ,*‘,’ I,,*. . . . ..*.. * ,; ,;.*5* .,.. .,‘,*..,*,. ., .I :*.* -*. .*a’ *. , ,, ,..’ ,*. . ..‘:‘. ‘, . * .‘.I... .**:,,..*..., . ..‘. . . . _‘. -s, \ , #*\:f.\. ., . , . ,_,:,;. ‘. . .:. . * I. j. ., . . , ., .I .,, ‘, --

--

.I.. ._,t--T _,_I. -- , .

-_--

-

*.

,

_. . g,.

-

20

. . _ , ..: : ;: :. . . :’ . .~.‘.,*‘;y.’ * . , :‘. . .’ : : ;’ ., I.. , : , ; ; ** y* ,.*. . ‘-‘:I; :\; .

40

-r-CA -

-

-_

--zz

I”< 1, ;, :.:.!,“_60 \. c -.1...* . ..\ \,;,. . ..,;;..,;..,. . t .,‘.I.’ .; .\.<, I.‘; i :rt..I. I . \.\ \.;. \ .‘,.,Y .j r, .,* .,‘. -.,.I I’... . I.. I . , .-, * . ; I :: : . .\; ,..I’, . .. .‘,’ r ._ . . St. ,.,, :-: .\,.I. ..I. _.,_ ,\‘. . 1 ‘I\ .’ I..’ 1: 1 ._y : ‘: :

Fig. 7. Schematic character

(Fig. 1) recorded the Canaway symbols deformed

lithospheric

of the vertical eastward.

Ridge,

range

rocks;

by metamorphic with broadly

24-40

fronts,

varying

(Mathur,

underplating

Devonian

of the Thomson crustal

horizons

velocity with depth, including

region.

Fold

intrusion;

40-70

a. Derived

profile

from

are not available

sediments;

Belt and other average

velocity

km-amorphous

a low velocity zone.

the

from shots at A east of

there is only diagramatic.

and younger

rocks with increasing

or magma

Basin

than 4 s two-way-time)

of the reflection

O-5 km represent

km-lower

Eromanga

1983). b. Velocity/depth

data (greater

the nature

metasediments/metavolcanics

Palaeozoic

for the central

Deep reflection

therefore

in the depth

section

seismic reflections

5-24

In (a),

km-highly

late Proterozoic-early and layered, upper

possibly

mantle

rocks

211

Thus the long-line refraction data alone can be interpreted in many ways. However, combined with the vertical reflection profiling data there seems to be a major difference in the geological character of the upper and lower crustal zones of the central Eromanga Basin, the upper crust under the sediments being effectively “transparent” and the lower crust displaying effectively a multiple series of short reflecting horizons. Some measure of credibility must therefore be accorded to a number of tectonic models mentioned below. Mueller (1977) has taken characteristics such as those found under the Eromanga Basin into account in his generalised model of the continental crust, emphasizing the diversity of possible tectonic situations which can arise. In this model the lower crust with velocities of about 7 km/s is composed of mafic metamorphic rocks with, perhaps, migmatitic rocks overlying amphibolite facies rocks contributing towards the rapid velocity increase at mid-crustal depths. The different character in the vertical reflection records from the upper and lower crust leads to speculation that tectonic episodes in these two crustal regions were different. The upper crust could be uniformly plutonic so that no seismic reflectors arise, or else it could be highly folded and faulted thus precluding the return of coherent seismic energy. This latter interpretation is preferred based on the comparatively low resistivities of the crust (Spence and Finlayson, 1982). The lower crustal reflection character could result from metamorphic “fronts” (Mueller, 1977) during some tectonic episode which may or may not be contemporaneous with upper crustal tectonism. Rutland (1982), for instance, has argued in favour of the separate development of the upper and lower crust in continental Australia. Much of the upper crustal rock in eastern Australia is envisaged as being reworked older continental material with platformal cover. The lower crustal rocks are considered to be from a different chelogenic cycle (global thermal cycle of the order of 1000 Ma) and this may result in a different seismic reflection character as well as causing a velocity unconformity corresponding to the mid-crustal horizon (Conrad discontinuity). Other mechanisms which may cause the lower crustal “laminated” seismic character include the introduction of basaltic melt fractions or some form of underplating by differentiated upper mantle components either at the time of cratonisation or later. Ewart et al. (1980) and Wass and Hollis (1983) have proposed such underplating for crustal thickening under eastern Australia. Similar episodes could arise during the cratonisation of back-arc or pericratonic basins to cause the la~nat~ structure under the Eromanga Basin. The structure under the Canaway Ridge (Fig. 6, profile 4) is enigmatic at this stage. Finlayson et al. (1983) have compared the velocity structure with that of Leven’s (1980) CQEW model from the Bowen Basin (Fig. 6, profile 9). However, this latter model, derived from seismic profiles recorded cross-strike, differs from the longer reversed profiles of Collins (1980) along the axis of the Bowen Basin (Fig. 6, profile 10). Collins interprets a lower-crustal horizon at slightly shallower depths

212

than Leven’s “Moho”

suggesting

may well be at 44-48 8.2 km/s

that they may be the same feature. The true Moho

km depth where both authors

are reached

below

similar

velocity

agree that velocities

gradients.

Thus

under

in excess of the Canaway

Ridge there is undoubtedly

a strong velocity feature at 34 km depth, but there is still

some doubt

it should be identified

about whether

with the Moho.

ACKNOWLEDGEMENTS

The author seismic

would like to acknowledge

refraction

Lock, Chris

survey

Rochford,

work was greatly leadership

Jim Whatman,

assisted

of John

the help and assistance

work by many

people, John

in particular

Williams

with the long-line

by Clive Collins,

and Jane Rogers.

by help from the BMR seismic reflection

Moss, John

Pinchin

and

Owen

Dixon

Jo

The field

crew under

(Geological

the

Survey

Queensland). This paper is published with the permission of the Director, Mineral Resources, Geology and Geophysics, Canberra, A.C.T.

of

Bureau of

REFERENCES

Bott, M.H.P.,

1971. The Interior

of The Earth.

Braile, L.W., 1977. Interpretation seismic

refraction

Geophys.

profiles.

Union,

Collins,

In: J.G. Heacock

R.B., 1975. Guide

Mantle.

C.D.N.,

1980. Crustal

C.D.N.,

structure

Ridge and Piedmont.

structure

Ewart,

Australia.

iavas

thickening. Finlayson,

Tennant

profiles.

Geophys.

D.M.,

Crust

Bowen Basin from deep seismic sounding.

MSc.

McArthur

Hogan,

COCORP

reflections

T.K.,

R.D.. 1979. Thin-skinned

seismic-reflection

in Europe.

1959.

Seismic

seismic velocity/depth

profiling

Geophysics.

recordings

of the Blue

40: 25-39.

of large

models of the upper lithosphere

BMR J. Aust. Geol. Geophys.,

Mineral.

and

central

explosions

in

Queensland,

of the Pilbara

8: 35-51.

and petrogenesis Australia-Possible

of the Tertiary

anorogenic

implications

for crustal

Petrol., 75: 129-152.

The

Australian provinces.

ACT.,

Basin from deep seismic sounding.

Aust. J. Phys., 12: 222-230.

southern

1979.

13: 178-188.

S., Oliver, J. and Hatcher,

Appalachians;

and Palaeozoic

D.M.,

The Earth’s

K. and Ross, J.A., 1980. The petrology

and

bly, Canberra, Finlayson,

Am,

7: 563-567.

LB. and

Australia.

Contrib.

Proterozoic

refraction

In: P.J. Hart (Editor),

Union.

of the southern

southern

B.J., 1983. Detailed northwest

A., Baxter,

mafic

Monogr..

Qld.

R., 1975. Deep crustal

Everingham,

southeastern Craton,

Geophys.

8: 19-34.

Geology,

Dohr, G.P. and Meissner,

Drummond,

using amplitude-corrected

Crust.

of crustal

Europe.

of the central

D.S., Brown, L.D., Kaufman,

in the crystalline

H.A.,

pp. 28-70.

The Earth’s

Am. Geophys.

Brisbane,

1983. Crustal

Cook, F.A., Albaugh,

Doyle,

London,

and Q structure

to the interpretation

Monogr.,

BMR J. Aust. Geol. Geophys., tectonics

(Editor),

seismic studies in western

Geophys.

Thesis, Univ. of Queensland, Collins,

Arnold,

Sot., 40: 145-176.

Gloss, H., 1969. Explosion and Upper

Edward

velocity gradients

20: 427-439.

Braile, L.W. and Smith, J.R. Astron.

of crustal

continental IASPEI

crust:

Programs

Explosion

seismic

and Abstracts,

IUGG

studies

in Archaean,

17th General

Assem-

pp. 84-85.

1982. Seismic crustal

Creek and Mount

structure

Isa. J. Geophys.

of the Proterozoic Res., 87: 10569-10578.

North

Australian

Craton

between

213 Fin&son, D.M. and Collins, C.D.N., 1980. A brief description of BMR portable seismic tape recording systems. Aust. Sot. Explor. Geophys. Bull., 11: 75-77. Finlayson, D.M. and McCracken, H.M., 1981. Crustal structure under the Sydney Basin and Lachlan Fold Belt, determined from explosion seismic studies. J. Geol. Sot. Aust., 28: 177-190. Finlayson, D.M., Prodehl, C. and Collins, C.D.N., 1979. Explosion seismic profiles and their implications for crustal evolution in southeastern Australia. BMR J. Aust. Geol. Geophys., 4: 234-252. Finlayson, D.M., Collins, C.D.N. and Lock, J., 1983. P-wave velocity features of the lithosphere under the Eromanga Basin, eastern Australia, including a prominant mid-crustal (Conrad?) discontinuity. Tectonophysics, 101: 267-291. Frey, H., 1982. MAGSAT scalar anomaly distribution: The global perspective. Geophys. Res. Len., 9: 277-280. Fuchs, K., 1969. On the properties of deep crustal reflectors. Z. Geophys., 35, 133-149. Harris, L.D. and Bayer, K.C., 1979. Sequential development of the Appalachian orogen above a master decollement-A hypothesis. Geology, 7: 568-572. Healy, J.H. and Warren, D.H., 1969. Explosion seismic studies in North America. In: P.J. Hart (Editor), The Earth’s Crust and Upper Mantle. Geophys. Monogr., Am. Geophys. Union, 13: 208-220. Kosminskaya, LP., Belyaevsky, N.A. and Volvovsky, I.S., 1969. Explosion seismology in the USSR. In: P.J. Hart (Editor), The Earth’s Crust and Upper Mantie. Geophys. Manogt., Am. Geophys. Union. 13: 195-208. Leven, J.H., 1980. Application of synthetic seismograms to the interpretation of crustal and upper mantle structure. PhD Thesis, Australian National Univ., Canberra, ACT. Liebscher, H.J., 1962. Reflexionshorizonte der tieferen Erdkruste im Bayer&hen Alpenvorland, abgeleitet aus Ergebnissen der Reflexionsseismik. Z. Geophys., 28: 162. Liu, Y.S.B. and Seers, K.J., 1982. A plackback system for portable seismic recorders. Bull. Aust. Sot. Explor. Geophys., 13: 77-81. Lock, J., 1983. Central Eromanga Basin seismic refraction surveys 1980, 1981; Operations report. Bur. Miner. Resour. Aust., Rec., 1983/29. Mathur, S.P., 1983, Preliminary deep crustai reflection results from the central Eromanga Basin, Australia. Tectonophysics, 100: 163-173. McLennan, S.M. and Taylor, S.R., 1982. Geochemical constraints on the growth of the continental crust. J. Geol., 90: 347-361. Mueller, S., 1977. A new model of the continental crust. In: J.G. Heacoek (Editor), The Earth’s Crust. Geophys. Mono& Am. Geophys. Union, 20: 289-317. Mueller, S. and Landisman, M., 1966. Seismic studies of the Earth’s crust in continents. Geophys. J.R. Astron. Sot., 10: 525-538. Muller, G. and Mueller, S., 1979. Travel-time and amplitude interpretation of crustal phases on the refraction profile Delta-W, Utah. Bull. Seismol. Sot. Am., 69: 1123-1132. Prodehl, C., 1970. Seismic refraction study of crustal structure in the western United States. Geol. Sot. Am. Bull., 81: 2629-2646. Prodehl, C., 1977. The structure of the crust-mantle boundary beneath North America and Europe 8s derived from explosion seismology. In: J.G. Heacock (Editor), The Earth’s Crust. Geophys. Monogr., Am. Geophys. Union, 20: 349-369. Ringwood, A.E., 1982. Phase transformations and differentiation in subducted lithosphere: Implications for mantle dynamics, basalt petrogenesis and crustal evolution. J. Geol., 90: 611-643. Rutland, R.W.R., 2982. On the growth and evolution of continental crust: A comparative tectonic approach. J. Proe. R. Sot. NSW, 115: 33-60. Sass, J.H. and Lachenbruch, A.H., 1979. Thermal regime of the Australian continental crust. in: M.W. McElhinny (Editor), The Earth, Its Origin, Structure and Evolution. Academic Press, New York, N.Y., pp. 301-351.

214

Smithson.

S.B., Brewer, J.A.. Kaufman,

crustal

structure

Wyoming. Sollogub.

S., Oliver, J.E. and Zawislak,

by COC’ORP

Mantle.

A.G. and Finlayson,

central

Eromanga

studies

Geophys.

reflection

and granulitic

in southeastern

Monogr..

R.L.. 1980. Complex

profiling

xenoliths.

Europe.

Am. Geophys.

D.M.. 1983. The resistivity

Basin, Queensland.

Wass, S.Y. and Hollis, J.D.. 1983. Crustal eclogitic

crustal

in the

Archean

Wind

River

lower Range.

Earth Planet. Sci. Lett.. 46: 295-305.

V.B., 1969. Seismic crustal

Crust and Upper Spence.

revealed

structure

using magnetotelluric growth

in southeastern

J. Metamorph.

Geol..

In: P.J. Hart (Editor),

Union.

The Earth’s

13: 1899395.

of the crust and upper mantle

techniques.

Australia--Evidence

1: 25545.

in the

J. Geol. Sot. Aust.. 30: l-16. from lower crustal