l:250,000 GEOLOGICAL SERIES-EXPLANATORY NOTES

CHARLEVILLE QUEENSLAND

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SHEET SG/55-10 INTERNATIONAL INDEX COMMONWEALTH OF AUSTRALIA

STATE OF QUEENSLAND

1:250,000 GEOLOGICAL SERIES-EXPLANATORY NOTES Charleville, Qld

SHEET SG/55-10 INTERNATIONAL INDEX COMPILED BY D. SENIOR

Published by the Bureau of Mineral Resources, Geology and Geophysics and issued under the authority of the Hon. R. W. C. Swartz, M.B.E., E.D., M.P, Minister for National Development 1971. COMMONWEALTH OF AUSTRALIA

DEPARTMENT OF NATIONAL DEVELOPMENT MINISTER: THE HON. R. W. C. SWARTZ, M.B.E., E.D., M.P. SECRETARY: L. F. BOTT, D.S.C.

BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS DIRECTOR: N. H. FISHER GEOLOGICAL BRANCH: ASSISTANT DIRECTOR: J. N. CASEY

STA TE OF QUEENSLAND DEPARTMENT OF MINES MINISTER: THE HON. R. A. CAMM UNDER SECRETARY: E. K. HEALEY

GEOLOGICAL SURVEY OF QUEENSLAND CHIEF GOVERNMENT GEOLOGIST: J. T. Wooos

Printed in Australia by the Tasmanian Government Printer, Hobart Explanatory Notes on the Charleville Geological Sheet Compiled by Daniele Senior

The Charleville Sheet area was mapped in 1968 as part of a regional geological reconnaissance of the Great Artesian Basin undertaken by the Bureau of Mineral Resources and the Geological Survey of Queensland.

Air-photographs at a scale of approximately 1 : 50,000 taken by the RAAF in 1954 provide a complete coverage of the area. Cadastral maps at a scale of 1 inch to 4 miles are available from the Queensland Department of Public Lands, Brisbane, and the photomosaics at 1 inch to 1 mile scale and 1 :250,000 planimetric maps from the Division of National Mapping, Canberra.

Access to the area is good. Bitumen roads connect Charleville Town with Brisbane (Warrego Highway) and Augathella (Mitchell Highway). Graded and formed roads join Charleville with Quilpie to the west (Diaman­ tina Developmental Road), Adavale to the northwest, and Cunnamulla via Wyandra to the south (Mitchell Highway). Most of these roads are negoti­ able in all weather, although 4-wheel-drive vehicles are desirable on the unsealed roads after heavy rain.

Charleville (population about 6000) is the only centre of settlement and serves the whole area. It has an all-weather runway and receives scheduled air-services from Sydney and Brisbane.

Previous investigations Before the 1968 survey ( Senior et al., 1969) there had been few regional geological investigations in the Charleville Sheet area. However, regional studies of the geology of Queensland (Whitehouse, 1940, 1941, 1954), of the subsurface water supplies in the Great Artesian Basin ( Ogilvie, 195 4), and of duricrust ( W oolnough, 192 7) are relevant.

Tanner ( 1966, 1968) discussed the Palaeozoic rocks beneath the Great Artesian Basin and specifically the Adavale Basin with reference to the area mapped. Heikkila ( 1966) described the Palaeozoic of the Adavale Basin, including the Cooladdi and Westgate Troughs in the Charleville Sheet area.

Gravity, seismic, and aeromagnetic surveys cover most of the area, and are particularly concentrated in the northwest; Bouguer anomalies are shown on the map. Table 1 summarizes the results of these surveys.

Six oil exploration wells were drilled in the area (Table 5) and are discussed in the Economic Geology section.

3 TABLE I-GEOPHYSICAL SURVEYS

YEAR ABB RE VIATED TITLE REFERENCE

Seismic sun•eys 1959-1960 Quilpie-Thargomindah Charleville Hier & Spivey, 1962 seismic survey 1961 Seismic survey Adavale area Hier & Spivey, 1961 1962 Reconnaissance survey Charleville Fjelstul, 1962 North area 1963 Detail survey Quilberry Creek Fjelstul & Beck, 1963 Prospect 1965 Augathella seismic survey AMOSEAS, 1965 1966 Adavale Basin detail survey Fjelstul & Rhodes, 1966

Gravity surreys 1960 Gravity traverse Quilpie to Roma Langron, 1962 1964 Semi-detailed gravity survey, Ada­ Darby, 1966 vale Basin 1964 Southern Queensland reconnais­ Lonsdale, 1965 sance gravity survey

Aeromagnetic survey 1961 Aeromagnetic survey of Quilpie­ Rollins, Steenland & Charleville-Thargomindah area Hier, 1961

PHYSIOGRAPHY The geomorphology of the area was discussed in detail by Mabbutt (Appendix 5 in Senior et al., 1969). The main drainage features are the south-flowing Warrego River which rises north of the area, and the Ward and Langlo tributaries (Fig. 1). The main channels have the braided habit characteristic of western Queensland. As the mean annual rainfall is small ( Charleville: 19 inches) and the potential evaporation exceeds 7 5 inches, all streams are ephemeral. The tributary systems begin to flow with between ½ and 1¼ inches of.local rain of at least moderate intensity, but the major chan­ nels are dependent on widespread rain (Mabbutt, Appendix 5 in Senior et al., 1969). The Warrego River, which has a hilly catchment area, has a potential yield of 700,000 acre feet. The main channels flow at intervals of one to two years; floods in the Warrego reach the Darling every other year. Extensive flooding of the alluvial plains occurs about twice per decade, fol­ lowing more than 4 inches of rain.

A Tertiary land surface is preserved as small remnants of silcrete in the Charleville Sheet area ( Fig. 1, unit 1 ) . Partial erosion of the land surface produced a dissected tract ( unit 2) consisting of mesas and low rounded hills, stripped of silcrete, and some red-soil plains which are derived from the breakdown of chemically altered Cretaceous and Tertiary rocks. The red soils commonly occur on flat surfaces or the flanks of anticlines.

4 Sllcrt1f11 surfaces

Dissacf11d tracts

Rolling downs

Sondploins

Alluvial ploms

-~~~-~___:_'°,:'

055/AI0/2: Complete stripping of the Tertiary land surface and underlying altered sediments in the axial zone of anticlines and along the margins of faults has resulted in undulating soil plains, the rolling downs ( unit 3), broken by a few rocky rises.

Structural depressions in the area are occupied by the main watercourses and are alluviated ( unit 5).

Reworking of Cainozoic sediments has resulted in extensive monotonous sandplains ( unit 4).

STRATIGRAPHY Tables 2-4 summarize the stratigraphy of the Charleville Sheet area. Stratigraphic nomenclature of the Devonian Adavale Group follows Tanner (1968) modified by Galloway (1970a, b). Nomenclature of the Jurassic to Lower Cretaceous follows Exon ( 1966), and that of the Rolling Downs Group Vine et al. (1967).

Subsurface data are available from six oil exploration wells, logs of water bores, and BMR Charleville Scout Hole 1. Formation tops of the oil exploration wells are given in Table 5.

Basement rocks in the Sheet area are predominantly low-grade meta­ morphics; some granite intrusions occur in the Nebine Ridge. In Tregole 1 and Alba 1, quartz-biotite gneiss was encountered on the flanks of the Nebine Ridge ( Campbell, 1965; Amo seas, 1966). This gneiss is similar to that found associated with granite in the Eulo Ridge, and by extrapolation is presumed to be of Devonian age (Senior et al., 1969). Folded, slightly metamorphosed sediments were intersected in Maryvale 1, Crichton 1, and Lowood 1 (Freeman & Stafford, 1966) ; these sediments were probably metamorphosed at the end of a late Silurian to early Devonian orogeny ( Senior et al., 1969).

Within the Sheet area, Devonian sediments have only been identified from Phillips-Sunray Quilberry 1, which was drilled on the northern flank of the Cooladdi Trough. Geophysical evidence shows that similar sediments occur in the Westgate Trough. Both troughs are southern extensions of the Adavale Basin, and contain up to 16,000 feet of sediments of the Devonian Adavale Group (Phillips, 1964).

The Gumbardo Formation is the oldest formation in the Adavale Group; only its eastern arkosic facies is present in the Charleville Sheet area. The Log Creek Formation ('Gilmore Formation' of Tanner, 1968) has been divided into a lower shale member and an upper sandstone member (Tanner, 1968). The formation is dominantly marine, the sandstone member con­ taining pelecypods, brachiopods, rare gastropods, and a few nautiloid frag-

6 TABEL 2: PALAEOZOIC STRATIGRAPHY.

Age Rock Unit Lithology Thickness Environment (Map symbol) (in feet)

Lower Permian (PI) Sandstone, siltstone, conglomerate 0-800? Continental

UNCONFORMITY

Upper Devonian to Buckabie Formation Red sandstone, siltstone, mudstone, Several Continental and shallow Lower Carboniferous (D-Cb) varicoloured in part thousand feet in marine troughs Etonvale Formation Siltstone, mudstone and sandstone, Maximum in Shallow marine (Dme) in part calcareous; dolomite excess of 2000 Cooladdi Dolomite Silty and ar$illaceous dolomite; 0-300 Shallow marine Member minor limestone Log Creek Formation Mudstone and siltstone; minor Maximum in Shallow marine, continental Middle Devonian quartz sa.ndstone, labile and sub­ excess of 2500 labile sandstone Bury Limestone Limestone, dolomite, minor cal­ ? Shallow marine Member careous siltstone Gumbardo Formation Arkose and arkosic conglomerate Maximum in Continental excess of 2500

UNCONFORMITY Palaeozoic (Pz) Schist, phyllite, granite, quartz­ biotite gneiss ments, and the shale member corals, pelecypods, brachiopods, bryozoans, and crinoid fragments. McKellar ( 1966a, b) assigns a Middle Devonian (probably lower Middle Devonian) age to the formation. Palynology of the sandstone member confirms a Middle Devonian age ( de Jersey, 1966). The Bury Limestone Member, which is the eastern facies of the shale member of this formation farther north in the basin, occurs in the deeper parts of the Cooladdi Trough but is not present in Quilberry 1 on the flanking shelf; it may also occur in the Westgate Trough.

The Etonvale Formation is mainly a elastic formation, with a thin basal carbonate member, the Cooladdi Dolomite. The Cooladdi Dolomite Member is the source of a prominent reflection throughout the Adavale Basin (Tan­ ner, 1968), but is not everywhere recognizable in the Charleville Sheet area; consequently its distribution in the troughs is difficult to determine. However, in Quilberry 1, 204 feet of Cooladdi Dolomite Member consisting of fine­ grained elastic material with dolomitized corals was intersected.

The Cooladdi Dolomite Member passes laterally eastwards into the Boree Salt Member, but salt has not yet been recognized in the Charleville Sheet area (Tanner, 1968). The continental to shallow marine Buckabie Formation occurs in Quilberry 1, where it is 121 feet thick. It thickens markedly towards the axes of the Cooladdi and Westgate Troughs, and may extend to 10,000 feet in structurally low areas in more northerly parts of the basin, according to seismic interpretation (Tanner, 1968). The formation is barren but is probably Upper Devonian to possibly Lower Carboniferous as it lies stratigraphically above the Middle Devonian Etonvale Formation (Tanner, 1968).

Permian sediments were found in Phillips-Sunray Dartmouth 1 ( Quilpie Sheet area) but were not intersected in Phillips-Sunray Quilberry 1. However, they probably occur in northwest Charleville Sheet area in structurally depressed areas. The upper and lower contacts of the Permian are uncon­ formities. Triassic sediments are known only from the northern part of the Adavale Basin. In the south it is presumed that erosion removed the Triassic and truncated the Permian. Jurassic sediments have been intersected by the six petroleum explor­ ation wells and by many of the deep water bores. A complete sequence from the Precipice Sandstone to the Hooray Sandstone is present.

Over the Nebine Ridge in eastern Charleville Sheet area the Precipice Sandstone rests unconformably on basement schist and gneiss. Spores from the Precipice Sandstone in Amoseas Alba 1 belong to Evans' ( 1965) division J1, regarded as Lower Jurassic in age, and marked by the first appearance of abundant Classopollis. In eastern Charleville Sheet area the deposit was laid down under terrestrial conditions in valleys on a pre-Jurassic topographic surface. Its distribution shows that it was confined to depressions (Freeman & Stafford, 1966).

8 The Evergreen Formation was intersected in Amoseas Alba 1 and Tre­ gole 1 and Orion Oil Co. Maryvale 1, Crichton 1, and Lowood 1. These wells are located near the crest of the Nebine Ridge. The Evergreen Forma­ tion intersected in Alba 1 contains a microflora equivalent to the J2 spore division of Evans ( 1965), identified from the Surat Basin. This confirms the continuity of the Surat Basin sequence across the Nebine Ridge (Senior et al., 1969). Muddy sediments of this formation were deposited in marine to brackish conditions and the sea trangressed westwards through topo­ graphically low areas where deposits on the western limb of the Nebine Ridge in the Eromanga Basin were laid down. The western limit of these deposits is unknown, but they may be restricted by a north-trending fault or mono­ cline which, for lack of evidence, is shown on the map mostly as a lineament (from Etona homestead-grid ref. 499754 to Authoringa homestead-grid ref. 466689).

The Hutton Sandstone is present in all the petroleum exploration wells of the area. In Quilberry 1, it rests unconformably on the Devonian to Car­ boniferous Buckabie Formation, and on the eastern side of the Eromanga Basin, over the Nebine Ridge, it rests on older Jurassic units. The Hutton Sandstone is 564 feet thick in Amoseas Tregole 1 near the crest of the Nebine Ridge; westwards it thins to 300 feet in Orion Oil Lowood 1. Paly­ nology indicates a Lower Jurassic age for the formation (Evans, 1966).

The Middle Jurassic Birkhead Formation was intersected in all the oil exploration wells and in a few deep water bores. It lacks marine fossils and was apparently deposited in a continental environment. The Adori Sandstone is conformable on the Birkhead Formation. In Orion Oil Lowood, Maryvale, and Crichton Nos. 1, it is present as a single non-marine unit of fine-grained white quartzose sandstone. Similar rocks were encountered in Amoseas Alba 1 and Tregole 1 but with more kaolinitic matrix in the sandstone.

The Westbourne Formation is conformable on the Adori Sandstone. It.is 415 feet thick in Charleville town bore (No. 16982) and thins south­ ward. The formation is Upper Jurassic and contains J5 and J6 spores.

The Upper Jurassic to Lower Cretaceous non-marine Hooray Sand­ stone is present over the whole of the area as a sheet about 700 feet thick. The top of the formation is readily recognized on gamma ray logs as there is a sharp contrast between the low radioactivity of the sandstone and the uniformly higher radioactivity of the overlying argillaceous sediments of the Rolling Downs Group.

Apart from small areas of rolling downs in structurally elevated areas, the dominant outcrop type of the Rolling Downs Group consists of chemi­ cally altered sediments. Chemical alteration has affected sediments through­ out the group to depths of about. 200 feet. Feldspar, rock fragments, and clay minerals are strongly kaolinized,. selectively silicified, ahd ferruginized.

9 TABLE 3: MESOZOIC STRATIGRAPHY.

Age Rock Unit Lithology Thickness Environment (Map symbol) (in feet)

Lower to Upper (Kld-Kw) Kaolinized, ferruginized, and sili­ cified sediments Winton Formation Labile sandstone, siltstone, mud-1 Fluviatile, lacustrine and (Kw) stone, in part calcareous; minor up to 1200 paludal coal Mackunda Formation Labile sandstone, siltstone, mud- \ Paralic (Kim) stone, in part calcareous; coquinite ) Alluru Mudstone Mudstone, siltstone, in part cal­ 0-500 Shallow marine Lower (Kia) careous; minor limestone Toolebuc Limestone Calcareous shale 0-50 Shallow marine (Kio) ~ Coreena Labile sandstone, siltstone, mud-} ]'.a Member stone, in part calcareous 8 ~ (Klc) 450-1150 Shallow marine :5 ,_, Doncaster Mudstone, minor sandstone and 0- ~ 8 Member siltstone, in part calcareous .>~ (Kid) Upper Jurassic to Hooray Sandstone Sublabile sandstone, quartzose 650-800 Fluviatile Lower Cretaceous (J-Kh) sandstone, conglomerate, minor siltstone Westbourne Formation Siltstone, quartzose sandstone, 270-450 Fluviatile Upper (Juw) micaceous sandstone, minor lignite and coal Adori Sandstone Labile sandstone, siltstone, mica­ 80-150 Fluviatile (Ja) ceous sandstone, minor lignite and coal Birkhead Formation Calcareous sublabile sandstone, 210-350 Fluviatile Middle (Jmb) siltstone, micaceous sandstone, minor lignite and coal Hutton Sandstone Quartzose sandstone, minor silt­ 250-564 Fluviatile (Jlh) stone and mudstone Evergreen Formation Sandstone, siltstone, mudstone 55-140 Shallow marine, estuarine, Lower (Jlc) lagoonal Precipice Sandstone Sandstone, siltstone, mudstone 40-140 Fluviatile (Jlp) TABLE 4: CAINOZOIC STRATIGRAPHY

Age Rock Unit Lithology Thickness Environment (Map symbol) (in feet)

Quaternary (Qa) Sand, silt, clay, soil, minor gravel 0-300 Fluviatile (Qs) Quartz sand 30 Aeolian (Qr) Sandy red earth, minor gravel 1-15 Pluvial and aeolian (Qc) Gravel, mostly silcrete Superficial Colluvial or alluvial

UNCONFORMITY (Cz) Medium to coarse quartzose sand- 0-200 Fluvia tile stone, conglomerate

UNCONFORMITY

Tertiary Glendower Formation Silcrete (silicified quartz sand- 0-25 Fluviatile (Tg) stone), quartzose sandstone, sandy conglomerate

(T) Silcrete, quartzose sandstone, sandy 25 Fluviatile conglomerate Limited relatively fresh outcrops of the Coreena and Doncaster Mem­ bers of the Wallumbilla Formation occur in eastern Charleville Sheet. Shelly macrofossils found there indicate a marine environment.

The Toolebuc Limestone is anomalous in that in Quilberry 1, limestone was not recorded from the cuttings in the interval that corresponds to the gamma ray anomaly. It is probable that in the mapped area the Toolebuc Limestone is little more than a calcareous shale which contains a small quantity of radiogenic minerals (Senior et al., 1969). Toolebuc Limestone occurs only in the western third of the Charleville Sheet. Its absence in the east is probably due to non-deposition, rather than erosion.

Three areas of outcrop of relatively unweathered Allam Mudstone occur in the extreme north along the east margin of the W arrego and Ward Rivers, and a belt of chemically altered outcrops extends south across the central part. Allam Mudstone was intersected in BMR Charleville Scout Hole 1, which was drilled near the crest of the Millie Anticline (Fig. 2). In the western third of Charleville Sheet the Allam Mudstone conformably overlies the Toolebuc Limestone. Where the Toolebuc Limestone was not deposited the Allam Mudstone rests with apparent conformity on the Coreena Member of the Wallumbilla Formation.

Late in the Lower Cretaceous an influx of volcanic detritus resulted in the deposition of labile arenites. Initially these were in paralic environments (Mackunda Formation), but the main deposition took place in fresh water (Winton Formation) in fluviatile, lacustrine, and paludal environments.

Fresh outcrops of Mackunda Formation are absent and chemically altered Mackunda Formation is restricted to a small area of flat-topped hills between the Ward and Warrego Rivers. Subsurface distribution is restricted to the west, the formation having been eroded from the Nebine Ridge area where Wallumbilla Formation sediments crop out. The Mackunda Formation is characteristically thinly bedded and this generally enables it to be differen­ tiated from the overlying more thickly bedded Winton Formation in areas where chemical alteration has destroyed evidence of marine fossils.

The Winton Formation is restricted to the western third of the area, having been eroded from the east. Only the upper chemically altered part of the formation crops out, and consists of kaolinitic sandstone, siltstone, and mudstone, with silicified mudstone (porcellanite) and thin iron-enriched beds. Fragmentary plant material, consisting of impressions of stems and leaves, occurs in the Winton Formation and many specimens of Phyllopteris lanceolata W alkom were collected from the base of the formation in the Quilberry Anticline in the adjacent Quilpie Sheet area. The fossil leaves indicate a Lower Cretaceous age (White, 1969).

12 B MR SCOUT HOLE CHARLEVILLE I

Grid reference 402748, Charleville I: 250,000 Sheet area

Red sandy soil Red -brown earthy c:iuortz sandstone Yellow silty sand

20 Grey-pink siltstone 1 some iron staining

.----:-.;:;;o:-:-:-~~ ~.:...'.....:.·---=--~....:....-.·- '..;(\})\·._)(;( Fine white quartz sand,minor siltstone Grey silty sand 40 ·';7'·'7':-c,-.-~ .·_:...,;,_,:_:..;..,.: ..,;.::',:,; ... ;.: Fine quartz sand with silt interbeds, minor iron oxides laminae Grey silty sand with pisolitic iron

60 Very fine pink-grey silty sand Grey silty sand

Fine red quartz sand

Silcrete,with sand lenses 80 White friable quartz sandstone I-" Siliceous sandstone

White very fine quartz sond,slightly induroted C 100 ...J White very fine friable quartz sand

Slightly pink very fine friable quartz sand 120 Unconformity Grey mudstone minor oxides

Pink grey 1 white siltstone interbeds 140 1 Cored interval showing recovery C 0 Blue -grey mud stone K 2a Palynological age (@ Mocrofossil 160 (i) Spore,pollen

" Laminar carbonaceous ?siltstone C 180

200 Block pyritic mudstone,lominated 2 @ K 2a

220 0

GOO/AI0/3

Fig. 2. Lithology of the Allam Mudstone and Tertiary sequence in BMR Scout Hole Charleville No. 1.

Senior et al. (1969) make a somewhat arbitrary division of the Tertiary sediments at the probable east limit of the main basin of deposition of the Tertiary Glendower River system, approximately the position of the present­ day Warrego River. Similar sediments, of loc~l extent, in the east are pro­ bably not part of the Glen dower River system but represent ·the deposits of

13 smaller river systems, possibly of similar age. Correlates of the Glendower Formation outside the probable limits of the Glendower basin are shown by the symbol T on the map. The Glendower Formation rests unconformably on differentially eroded chemically altered Lower Cretaceous sediments. Unconsolidated to slightly indurated quartzose sandstone and quartz pebble conglomerate of Cainozoic age crop out along parts of Angellala Creek. The thickest section seen, 45 feet, is close to the base level of Angellala Creek. If the adjacent low sand-covered hills also contain the same sediments the deposit has a true outcrop thickness of approximately 200 feet. Some of the higher conglomerate beds are cemented with iron oxides. Similar unconsolidated sandstone occurs below other sandplains as indicated by the section drilled in BMR Charleville Scout Hole 1 (Fig. 2). Despite the limited outcrop and drill-hole evidence, the deposit is probably widespread. Thin Quaternary sediments are mainly locally derived colluvium and alluvium. The sediments are widespread, especially in the southern half of the Sheet, and some may be reworked late Tertiary fluviatile deposits. Near the Warrego and Ward Rivers the alluvium may be 300 feet thick. TABLE 5. FORMATION TOPS OF OIL EXPLORATION WELLS Quilberry Maryvale Crichton Lowood Alba Tregole Formation tops 1 1 1 1 1 1

Grid references 345719 493687 494685 495683 503707 509714 Winton and Mackunda Formations 0 Eroded Eroded Eroded Eroded Eroded Allam Mudstone 75 Eroded Eroded Eroded Eroded Eroded Toolebuc Limestone 680 Eroded Eroded Eroded Eroded Eroded Coreena Member 730 Eroded Eroded Eroded Eroded Eroded Doncaster Member Not picked 0 0 0 0 0 Hooray Sandstone 1,700 602 558 512 591 356 Westbourne 2,300 1,459 1,360 1,380 1,125 800 Formation Adori Sandstone 2,575 1,790 1,660 1,660 1,460 1,257 Birkhead Formation 2,720 1,874 1,806 1,780 1,600 1,372 Hutton Sandstone 2,930 2,204 2,100 2,132 1,915 1,720 Evergreen Not 2,606 2,502 2,432 2,433 2,284 Formation present Precipice Sandstone Not 2,662 2,572 Not 2,572 2,395 present present Buckabie Formation 3,380 Not Not Not Not Not present present present present present Etonvale Formation 3,500 Not Not Not Not Not present present present present present Cooladdi Dolomite 5,410 Not Not Not Not Not Member present present present present present Log Creek 5,610 Not Not Not Not Not Formation present present present present present Gumbardo 7,825 Not Not Not Not Not Formation present present present present present Basement Not 2,731 2,609 2,478 2,705 2,459 reached Total depth 10,013 2,772 2,670 2,532 2,713 2,475 References: Quilberry 1-Cundill, Meyers & Associates, 1965; Maryvale 1, Crichton 1, Lowood I-Freeman & Stafford, 1966; Alba I-Campbell, 1965; Tregole 1- Amoseas, 1966.

14 STRUCTURE Broadly, the Charleville Sheet area consists of two Devonian to Car­ boniferous troughs, the Cooladdi Trough in the west and the Westgate Trough in the centre, with a basement platform which rises gently in the east to form the Nebine Ridge.

The troughs trend northwest and north respectively and have steep­ sided or fault-bounded margins ( Tanner, 1968). Flat-lying sediments, uncon­ formably overlying those in the troughs, are disturbed in places by shallow symmetrical folds or by faults.

The Nebine Ridge, a gentle rise in the metamorphic basement, extends from the Nogoa Anticline in the Springsure Sheet area (Mollan, 1967) south to the Wyandra Sheet area (Thomas, in prep.), where it merges with the Cunnamulla Shelf. Late Cretaceous and early Tertiary earth movements resulted in uplift and erosion of post-Wallumbilla sediments from the ridge area. However, the structure of the pre-Wallumbilla Hooray Sandstone now reflects the basement Nebine Ridge. Contours on the top of the Hooray Sandstone (Fig. 3) illustrate the position of the Nebine Ridge in the east of the Sheet area.

Fresh Cretaceous outcrop and dips on remnant Tertiary surfaces are used to delineate folds, such as the Quilberry and Tumbleberry Anticlines,

147°001 26°00' •R4089 -417

--soo- f:t:~::r, ;'0//1.:r.z::::::::::n:: ... , 10 20 30 KILOMETRES • 112411 wa,.,. bor• •ifh r•11iafHH numb•r, 10 20 MILES -1oa 1/11/n, •J•11oli011 ol top of Hooray Sand1fon• • !'i: ~;' ,:f~°f°,f{::;•ff~:~:::::'•11ation GOO/AI0/4 Fig. 3. Contours of top of Hooray Sandstone.

15 as well as the lineament and fault in the east, which is interpreted as a base­ ment rise with slight monoclinal flexuring of the Mesozoic sediments.

The Millie Anticline and Biddenham Syncline have no surface expres­ sion and their axes are seismically defined. The contours on the top of the Hooray Sandstone (Fig. 3) illustrate the position of the Biddenham Syncline ( central Charleville Sheet) and the Millie Anticline just to the west.

GEOLOGICAL HISTORY The basement rocks were strongly folded and slightly metamorphosed at the end of a late Silurian to early Devonian orogeny (Senior et al., 1969). The Devonian Adavale Group sediments were deposited on the western shelf of the Tasman Geosyncline (Tanner, 1968). Volcanic sedimentation (Gum­ bardo Formation) early in the Middle Devonian, was followed by marine deposition (Log Creek Formation). The area was then uplifted and eroded before a return to marine conditions ( Cooladdi Dolomite Member of Eton­ vale Formation). A marine environment continuing throughout the deposi­ tion of the Etonvale Formation gave way to continental conditions of low­ lying and fluvial flood plains and saline lakes during deposition of the Buckabie Formation (Tanner, 1968).

Epeirogenic movement in late Carboniferous ttme resulted in down­ warping of the Devonian sediments in the troughs, and erosion of the Devonian and levelling of the basement rocks in the intervening areas.

Continental conditions existed throughout the Permian and Triassic. Epeirogenic movements after the Triassic and subsequent erosion possibly removed all Permian and Triassic sediments from the structurally high areas, leaving Permian remnants in the structurally low areas.

The Devonian Nebine Ridge was eroded and became a low-lying area in early Jurassic time. It had little effect on Jurassic to Cretaceous deposition, as is shown by the increase in thickness of lower Jurassic formations near the crest of the Ridge. In Lower Jurassic times sedimentation was at first restricted to the area of the Nebine Ridge. Initially deposition was by rivers, but a short-lived marine transgression allowed deposition of fine-grained sediments, both in the seas and in marginal lagoons and estuaries. By the end of the Lower Jurassic, fluviatile deposition was taking place throughout the whole area. Continental conditions continued throughout the rest of the Jurassic and into the early Cretaceous.

The seas flooded the area again in the Lower Cretaceous and did not recede until Winton Formation time. After the Winton deposition the area was peneplaned and deeply weathered before the deposition of fluviatile Ter­ tiary sediments.

16 Further silicification and leaching occurred during the Tertiary. Earth movements in late Cretaceous or early Tertiary time formed the present incomplete structural divide between the Eromanga and Surat Basins.

Deposition of thick alluvial deposits occurred in the structurally low areas during the Tertiary and Quaternary.

ECONOMIC GEOLOGY Groundwater One hundred and forty eight bores have been drilled in the Charleville Sheet area; of these 28 are still flowing, 36 have ceased to flow, 65 are sub­ artesian and 19 are abandoned. Amoseas Alba 1 was completed as a sub­ artesian water bore obtaining water from the Hooray Sandstone.

The bores are mainly used for stock water; however, Charleville town bore 16982 provides inhabitants with domestic and industrial supply. Some homesteads are situated close to artesian bores

The most utilized aquifers are from the Hooray, Adori, and Hutton Sandstones. Limited local supplies of brackish water are available from the Coreena Member of the Wallumbilla Formation, and water of variable quality from Quaternary aquifers.

The depth to the pre-Hooray aquifers limits their use. The pressure in these aquifers is high and they are used in areas where Hooray Sandstone aquifers have ceased to flow or where pressure has dropped markedly. Charleville town bores 334 and 335 were completed in the Hooray Sand­ stone; but a continuous fall in pressure prompted the drilling of Bore 16982 to 3660 feet to tap Adori Sandstone and Hutton Sandstone aquifers. This bore had an initial flow in 1967 of about 30,000 gallons per hour.

Artesian water from the Hooray Sandstone is available at the present time only in low-lying areas, mainly those near the Warrego and Ward Rivers. The present potentiometric surface is below the ground surface for the rest of the Sheet area and bores in these higher areas have ceased to flow.

The loss of pressure in Hooray Sandstone aquifers is attributed to over-production and lack of control of free-flowing bores (Senior et al., 1969). However, in the more elevated areas of the Nebine Ridge, in the northeast, flowing water at the surface was probably never available and in this area only subartesian water is available from Hooray Sandstone aquifers.

Quaternary aquifers exist along the W arrego River and are especially utilized near Charleville town. Many very shallow wells dug into Quaternary aquifers have ceased to produce, but deeper wells and bores are still produc­ ing adequate supplies.

17 Table 6 summarizes properties of bores with subsurface information.

TABLE 6. BORES WITH SUBSURFACE INFORMATION

QIWSC Initial Registered Depth Aquifers Flow Status Grid No. GPH Ref. 50 1947 Hooray Sandstone A 391690 51 2900 Adori and Hutton Sandstone A 364698 52 1990 Hooray Sandstone B 399695 96 2290 Adori ~nd Hutton Sandstones 45,830 A 366657 1197 3335 Hooray Sandstone A 457705 1291 1221 Hooray Sandstone B 465674 1292 1004 Hooray Sandstone B 463672 1296 720 Hooray Sandstone B 479666 1297 890 Hooray Sandstone B 473668 1561 2304 Hooray Sst. & lnjune Creek B 489652 Group 1563 2427 Hooray Sandstone B 483662 1556 2015 Hooray Sst. & Injune Creek B 467659 Group 1811 2628 Hooray Sandstone B 369734 1812 2518 Hooray Sandstone B 383763 2000 1488 Hooray Sandstone B 417720 2001 2092 Hooray Sandstone 2,500 B 418739 2002 1460 Hooray Sandstone B 419737 2004 184 Quaternary C 433733 2005 160 Quaternary C 426731 2411 3027 Hooray Sandstone 33,330 B 389707 2412 2010 Hooray Sandstone B 397664 4001 1800 Hooray Sandstone A 409653 4089 2209 Hooray Sandstone 75,000 B 399766 4686 2200 Hooray Sandstone & Injune Creek Group 10,420 B 506659 4963 1302 Hooray Sandstone 7,000 B 443727 4964 1040 Hooray Sandstone B 455744 5008 3500 Adori & Hutton Sandstones A 430746 5021 1600 Coreena Member C 426764 5284 1560 Hooray Sandstone A 416669 5387 862 Coreena Member C 385724 7001 812 Coreena Member A 473654 8393 1175 Hooray Sandstone C 449717 10782 400 Coreena Member C 447768 12028 2430 Hooray Sandstone A 347669 12083 317 Quaternary C 421722 12328 903 Coreena Member C 481734 13642 875 Hooray Sandstone C 501664 13767 1704 Hooray Sandstone C 423754 14031 490 Coreena Member C 446667 14295 1265 Hooray Sandstone C 444708 Status: A = Artesian B = Artesian ceased to flow C = Subartesian

Hydrocarbons Details of the six oil exploration wells in the area are summarized in Table 5.

Phillips-Sunray Quilberry 1 was drilled near the culmination of a surface- expressed anticline on the north flank of the Cooladdi Trough to investigate

18 thick Devonian marine sediments unconformably below the Mesozoic. The Mesozoic sandstones were found to contain fresh water and the pre-Permian sediments were impermeable. The well was plugged and abandoned.

Amoseas Tregole 1 and Alba 1 located near the crest of the Nebine Ridge were drilled to test the Lower Jurassic sediments for hydrocarbons in stratigraphic traps. In both wells the main targets were the Evergreen Forma­ tion and the Precipice Sandstone, which have some evidence of marine or brackish water conditions in their depositional history. Although good poros­ ity and permeability were found in the Precipice Sandstone, Hutton Sand­ stone, Injune Creek Group, and Hooray Sandstone, all the formations were saturated with water. No significant oil shows were encountered in Tregole 1 and the target beds were regarded as water-flushed. In Alba 1, no shows of oil or gas were found in the well except for spotty fluorescence with a very weak carbon tetrachloride cut from a sidewall core from 2630 feet. Tregole 1 was plugged and abandoned and Alba 1 completed as a water bore.

Orion Oil Maryvale 1, Crichton 1, and Lowood 1, sited near the crest of the Nebine Ridge, were drilled with the main object of encountering strandline (pinch-out) stratigraphic traps in the Lower Jurassic Precipice Sandstone. Methane was detected from the Hooray Sandstone and West­ bourne Formation from the interval 1100-1430 feet in Lowood 1. Freshwater aquifers in this interval carry methane in solution. Fluorescence and carbon tetrachloride cut occurred in a core from 2508 feet and 2533 feet (Hutton Sandstone) in Crichton 1. In Maryvale 1 cores showed fluorescence and cut in the interval 2 715 feet to 2 722 feet ( Precipice Sandstone) . All three wells were plugged and abandoned.

The Westgate Trough, with a Devonian sequence up to 16,000 feet thick, has not been drilled. The sediments are largely marine in origin and could be source beds for hydrocarbons. The steep margins to the trough, which are in part faulted, could provide traps if suitable reservoir beds occur. However, drilling in other southern extensions of the Adavale Basin has shown that the Devonian is generally impermeable.

The Mesozoic sequence in the area has been indirectly explored by numerous water-bore drillers without any shows of hydrocarbons. Reservoir characteristics are excellent for this sequence but it appears to be fully water-flushed.

Construction material Gravel and sand are available in sufficient quantities to supply local needs. The Warrego Highway was built with locally won silcrete gravel.

Deposits of quartz sand and cong!omerate, some 200 feet thick, occur in the vicinity of Angellala Creek. They could be u.-:ed for concrete aggregate.

19 BIBLIOGRAPHY (Unpublished reports marked * refer to operations subsidized under the Petroleum Search Subsidy Acts, 1959-1964; copies are available for study at the Bureau of Mineral Resources, Canberra and the Geological Survey of Queensland. Unpublished reports marked t refer to unsubsidized operations available for study at the Bureau of Mineral Resources, Canberra and the Geological Survey of Queensland.) *AMOSEAS, 1965-Augathella Seismic Survey Authority to Prospect 65/4584 101P, Qld. American Overseas Petroleum Ltd (unpubl.). *AMosEAs, 1966-Tregole No. 1 well completion report. Ibid. *AOD, 1963-Completion report Canaway Well No. 1 ATP. 98P. Alliance Oil Development N.L. (unpubl.). *CAMPBELL, I. R., 1965-Final report of the Mitchell-Morven test drilling project. American Overseas Petroleum Ltd (unpubl.). *CUNDILL MEYERS & ASSOCIATES, 1965-Well completion report. Quilberry No. 1 ATP 72P, Qld. Phillips Petroleum Co. (unpubl.). 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Aust. Ree. 1962/47 (unpubl.). LONSDALE, G. F., 1965-Southern Queensland contract reconnaissance gravity survey using helicopters, 1964. Bur. Miner. Resou,·. Aust. Ree. 1965/251 (unpubl.). MABBUTT, J. R., 1965-The weathered land surface in Central Australia. Z. Geomorph., N.F., 9(1 ), 82-114. *MCDONAGH, c., KNUTH, B. w., and PATTERSON, w. A., 1966----Phillips-Sunray Leopardwood No. 1 ATP 109P Qld, well completion report. Phillips Australian Oil Co. (unpubl.). MCKELLAR, R. G., 1966a-Devonian marine fossils from the subsurface Adavale Basin Queensland. Geol. Surv. Qld Pub/. 332, 1-6 (Palaeont. Pap. 2). MCKELLAR, R. G., 1966b-Additional brachiopods and bivalves from the Etonvale Formation, Adavale Basin, Queensland. Geol. Surv. Qld Pub[. 332, 11-17 (Palaeont. Pap. 4). MoLLAN, R. G., 1967-Springsure, Qld-1 :250,000 Geological Series. Bur. Miner. Resour. Aust. exp/an. Notes SG/55-3. OGILVIE, C., 1954-The hydrology of the Queensland portion of the Great Australian Artesian Basin. 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M., and SENIOR, DANIELE, 1699-The Geology of the Quilpie, Charleville, Toompine, Wyandra, Eulo, and Cunnamulla 1 :250,000 Sheet areas. Bur. Miner. Resour. Aust. Ree. 1969/13 (unpubl.). TANNER, J. J., 1966-Distribution of Palaeozoic rocks beneath the Great Artesian Basin, Queensland. APEA J., 1966. 116-20. TANNER, J. J., 1968-Devonian of the Adavale Basin, Queensland, Australia. Int. Symp. Dev. System, Calgary 1967, 2, 111-6. *TALLIS, N. C., and FJELSTUL, C. R., 1966-Geophysical report reconnaissance and detail seismograph survey of Lake Dartmarth area, ATP I 09P Queensland, Aus­ tralia. Phillips Petroleum Co. ( unpubl.). THOMAS, B. M., in prep.-Wyandra, Qld-1 :250,000 Geological Series. Bur. Miner. Resour. Aust. explan, Notes SG/55-14. VINE, R.R., DAY, R. W., CASEY, D. J., MILLIGAN, E. N., GALLOWAY, M. C., and ExoN, N. E., 1967-Revised nomenclature of the Rolling Downs Group, Eromanga and Surat Basins. Q/d Govt Min. J., 68, 144-51. 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21 WHITEHOUSE, F. W., 1954-The geology of the Queensland portion of the Great Aus­ tralian Artesian Basin. Appendix G to Artesian water supplies in Queensland. Dep. Co-ord. Gen. Pub!. Works, Qld. WILLIAMS, G. D., 1966-The Great Artesian Basin-origin and history. APEA J., 1966, 88-92. WooLNOUGH, W. G., 1927-Presidential Address, Part I-The chemical criteria of peneplanation; Part II-The duricrust of Australia. J. Roy. Soc. NSW, 61, 17-53. WoPFNER, H., 1960-On some structural development in the central part of the Great Australian Artesian Basin. Trans. Roy. Soc. S. Aust., 83, 179-93. WoPFNER, H., 1964-Permian-Jurassic history of the Western Great Artesian Basin. Ibid., 88, 117-28.

T. J. HUGHES, Government Printer, Tasmania.