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BMR Record 1972111

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COMMOruWIEALTH Of AUSTRALIA

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Record 1972/11 '

GALILEE BASIN DETAILED , GRAVITY SURVEY, QUE~NSLAND,

, 1971

- OPERATIONAL REPORT

by

W. Anfiloff

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of the policy of the Commonwealth Government to assist in the exploration and development of mineral resources, It may not be published in any form or used in a company prospectus or statement without the permission in writing of the Director. Bureau of Mineral Resources. Geology & Geophysics.

I I I I I I I I I I I I I I I I I· I I I

Record 1972/11

GALILE E BASIN DETAILED GRAVITY SURVEY, QUEENSLAND,

· 1971

- OPERATIONAL REPORT

by

w. Anfiloff

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1.

2.

3.

4.

CONTENTS

SUMMARY

INTRODUCTION

TIE POINT, TRAVERSE, AND ROCK SAMPLE SPECIFICATIONS

DETAILS OF OPERATIONS

REFERENCES

PLATES

PLATE 1 - Location Map

PLATE 2 .. Preliminary gravity profiles

Page

1

1

4

5

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SUMMARY

The gravity survey was carried out along a seismic traverse from Lake Galilee No.1 well to Drummond Group outcrops in the east. In addition, work was done on: several cross traverses, and on a line extendirigeastwards from the end of the seismic line. This has produced a strip Of detailed gravity data across the boundary between the Galilee and Drummond Basins.

:No 1arge difference from the previous reconnaissance results has been'lobserved, but the present survey has revealed· several. short wavelengtb anomalies which were not previously reco;rded. 'r~e may add Significantly to the structural picture of the area. .

I I I I I I I I I I I I I I I I I

1. iNTRODUCTION

During the period 11 October to 26 November 1971, the Bureau of Mineral Resources (BMR) carried out a gravity survey in the Galilee Basin concurrently with a seismic survey (Harrison et al., 1971), over traverses totalling 185 km in length. The main objective of these surveys was to define the structural configuration of the eastern margin of the Galilee Basin, and its ' relationship to the western margin of the Drummond Basin.

The area covered is an east-west strip 95 km long, and 16 km wide extending eastwards from survey marker AB6, along the seismic traverse and beyond to "Beresford" homestead (Plate 1). The survey encompassed

. six sites previously occupied during the reconnaissance helicopter gravity survey in 1963 (Gibb, 1966), and was finally tied to Isogal station 6491.0250 at Clermont (Barlow, 1964).

This report provides information on the operational aspects of the gravity survey and includes preliminary gravity profiles for the main traverse, and six cross traverses (Plate 2).

2. TIE POINT, TRAVERSE, AND ROCK SAMPLE SPECIFICATIONS

Ties to previous work

A comparison of existing and newly derived observed gravities is shown in Table 1, based on the value of the Clermont Isogal station.

TABLE 1

BASE OBSERVED GRAVITY OBSERVED GRAVITY DIFFERENCE . mgl. (1963) mgl. (1971) mgl .

6306.0805 978715.16 978715.11 -0.05

6306.0806 978715.16 978715.54 -0.07

6306.0807 978716.14 978716.05 -0.09

6306.1253 978764.18 978764.13 -0.05

6306.1254 978764.87 978764.88 0.01

6306.1255 978764.66 .978764.52 -0.14

I.~------------------------------6491.0250 978775.64 978775.64 0.00

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Tie station elevations

Elevations of previously established tie points and their newly assigned B.M.R. gravity station numbers are shown in Table · 2.

TABLE 2

MARKER 8MR GRAVITY STN NO. ELEVATION (metres)

AB5 6306.0805 302.36

AB6 6306.0806 299.00

AB7 6306.0807 301.44

AG53 6306.1253 230.43

AG54 6306.1254 237.44

AG55 6306.1255 241.09

Specifications for the main and cross traverses

Traverse specifications for gravity survey No. 7107 are given in Table 3. '

TABLE 3

STATION SERiES INTERVAL LOCATION NO.

7107.1068- : Seismic 540 metres Coincident with SPI068 to SP1173 7107.1173 traverse

7107.2001- 2000 Various between Along road from " Langlan" 7107.2046 0.05 to 0.8 km to "Beresford", starting

at 6306.1254 (AG54) and ending at permanent marker 7107.9001

7107.5001- 5000 0.8 km Cross traverse along road from 7107.5015 AB5 to AB7 via AB6

7107.5102- 5100 0.8 km Cross traverse along dog-proof 7107.5229 fence crossing seismic traverse

at SP 1100 8/12

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7107.5211-7107.5229

5200 0.8 km Cross traverse along road and fenceline, intersecting seismic traverse at SP 1155 and SP 1157

7107.5301-7107.5319

5300 0.8 km Cross traverse along road from AG53 to AG55 via AG54

7107.5401-7107.5418

5400 0.8 km Cross traverse along fencelines, intersecting main traverse at 7107.2023

7107.5501-7107.5517

5500 0.8 km Cross traverse along track,

Rock sample specifications

intersecting main traverse at 7107.2042 and 7107.2043

Descriptions of rock samples collected for density determination are shown in Table 4.

TABLE 4

Number Rock type Description Strat. Unit Location DensifJ. (g/cm )

. N1 Conglomerate Buff-coloured, Mt Hall Mt Bingeringo 2.50 even-grained Formation matrix with we 11 rounded pebbles

N2 Quartzite White, even- Mt Hall Mt Bingeringo 2.48 grained, Formation arkosic

N3 Conglomerate Red, with Mt Hall Mt Bingeringo 2.59 coarse uneven Formation matrix and rounded to angular pebbles

N4 Conglomerate Pink, coarse Mt Hall Mt Bingeringo 2.50 even-grained Formation matrix with rounded pebbles

SI

S2

S3

54

Conglomerate

Feldspathic quartz sandstone

Rhyolite

Rhyolite

-4-

Dark red, with uneven matrix and angular to rounded pebbles; hematite and dark mineral inclusions

White to pink, medium-grained

Dark-coloured pyroclastic

Buff - coloured, porphyritic, flow- banded

Mt Hall Formation

Mt Hall Formation

Silver Hill Volcanics

Silver Hill Volcanics

Mt DOIUlybrook

Mt Donnybrook

Piebald Creek east of Mistake Creek Syncline

12 km N.E. of "Pioneer"

3. DETAILS OF OPERATIONS

PersoIUlel

The field operations were carried out by the following persoIUlel, under the overall supervision of F. W. Brown.

W. Anfiloff

C. Allen

T. Hoffman

T. Plant

Geophysicist

Technical Assistant

Surveyor

Surveyor's assistant

2.74

2.37

2.57

2.41

D. Glasson Surveyor's assistant (after completion of seismic traversing)

Survey -statistics

The operations began on 11/10/71 and ended on 10/11/71. Within . this period, the traverses were recoIUloitred, and stations pegged, photo identified, and occupied for gravity observations. A total of 385· observations were made, which provided 265 new station values. Geological excursions were made in the vicinity of Mount DOIUlybrook, and further north at Mount Bingeringo, and rock samples were collected for density determin~tion.

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Log of activities

Reconnaissance of traverses, photo identification of stations, and pegging of stations: Geological reconnaissance: Gravity observations:

Levelling

5 days 3 days

12 days

Eight days were spent levelling traverses extra to the seismic line. Surveying control was avallable at six established survey markers (Table 2).

Equipment

1 Gravity meter, MW548 (C.F. = 0.10937 mgl/div.)

1 L/R 4 x 4 for gravity work

1 L/R 4 x 4 for surveying work

After the completion of work on the seismic line, two Land Rovers and two rod men were used on the surveying operation.

4. REFERENCES

BARLOW, B.C., 1964 - The Australian Isogal Survey, 1964. Bur. Miner. Resour. Aust. Rec. (in prep., unpubl.). .

GIBB, R .A., 1966 - North Eromanga and Drummond Basins reconnaissance gravity surveys, Queensland 1959-1963. Bur. Miner. Resour. Aust. Rec. 1966/210 (unpubl.).

HARRISON, P., and BROWN, A.R., 1971 - Galilee Basin Seismic Survey Queensland, 1971 - Operational Report. Bur. Miner. Resour. Aust. ~. 1971/138 (unpubl.).

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BASIN DETAILED GRAVITY SURVEY 1971 LOCATION MAP

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