DEPARTMENT OF MINERALS AND ENERGY BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS

DEPARTMENT OF MINES, STATE OF GEOLOGICAL SURVEY OF QUEENSLAND

1:250000 GEOLOGICAL SERIES-EXPLANATORY NOTES GILBERTON QUEENSLAND SHEET SEj54-16 INTERNATIONAL INDEX

COMPILED BY J. SMART

AUSTRALIAN GOVERNMENT PUBLISHING SERVICE, CANBERRA, 1973 DEPARTMENT OF MINERALS AND ENERGY MINISTER: THE HON. R. F. X. CoNNOR, M.P. SECRETARY:SIR LENOX HEwrrr, O.B.E.

BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS DIRECTOR:N. H. FISHER ASSISTANTDIRECTOR,GEOLOGICALBRANCH:J. N. CASEY

DEPARTMENT OF MINES, STATE OF QUEENSLAND MINISTER: THE HON. R. E. CAMM, M.L.A. UNDER-SECRETARY:E. K. HEALY, I.S.O.

GEOLOGICAL SURVEY OF QUEENSLAND CHIEF GOVERNMENTGEOLOGIST:J. T. WOODS

Published for the Bureau of Mineral Resources, Geology and Geophysics by the Australian Government Publishing Service

Printed bl/ Graphic Services P17 Ltd. 60 Wl/att Street. Adelaide. S.A. 5000 Explanatory Notes on the Gilberton Geological Sheet 2nd EDITION

Compiled by J. Smart

The Gilberton 1:250 000 Sheet area is bounded by latitudes 19·00'S and 20·OO'S, and longitudes 142°30'E and 144°00'E; it contains the mineral fields of Gilberton, Percyville, and Woolgar, and part of the Great Artesian Basin. The area is divided into three distinct geological and geographical units: the , which crosses the area from northwest to southeast, and joins the a few kilometres east of the Sheet boundary; the Claraville Plain, covering the western half of the Sheet area; and the Georgetown lnlier in the northeast corner. There are no towns, main roads, or railways in the area; a network of station tracks provides access into the west; roads in the Gregory Range are few and access is difficult. In the northeast there is reasonable access along tracks to Gilber• ton and percyvilIe homesteads. Some homesteads maintain airstrips. Air-photographs at a nominal scale of 1: 80 000 taken by Adastra Surveys in 1967 provide a complete coverage of the area. Topographic maps at 1:250000 scale are available from the Division of National Mapping, Canberra, and cadastral maps at 4 miles to 1 inch (1 :253440) from the Queensland Department of Lands, . The area was geologically mapped in 1956 and 1958 by a combined party from the Bureau of Mineral Resources (BMR) and the Geological Survey of Queensland (GSQ); the 1st Edition geological map was published in 1962. In 1969, another combined geological party remapped the Mesozoic and younger formations and re-examined the Precambrian in the southeast. These notes incor• porate the work of both parties. In 1970, BMR carried out shallow stratigraphic drilling in the south (Needham et al., 1971).

Previous investigatioM Daintree (1870, 1872) made the first geological reconnaissance of the Gilberton Sheet area; in 1872 he produced the first geological map of Queensland, which showed Lower Silurian 'metamorphic-mica schist, intruded by dykes of elvanite, diorite, hornblende rocks, etc.', in the Gilberton Mineral Field. In 1898 Maitland attempted to delineate the artesian water area west of the Gregory Range, and provided the first comprehensive account of the hydrology. Cameron (1900) and, later in more detail, Ball (1915) investigated the mines and mineral deposits in the PercyvilIe and Woolgar areas. Saint-Smith (1922) re• ported on the Woolgar Goldfield and provided a comprehensive account of the gold mining. Jensen (1923) made a broad reconnaissance of the Cairns hinterland which included the Precambrian part of the Gilberton Sheet area. No further geological surveys were made until 1945, when Morton surveyed the scheelite deposit at Percyville, and Ridgeway the agate deposit at Agate Creek. 3 Whitehouse (1955) and Ogilvie (1955) studied the geology and hydrology of the Great Artesian Basin for the Queensland Co-ordinator General's Department. In 1953 and 1954 the Land Research and Regional Survey Section, Common• wealth Scientific and Industrial Research Organization (CSIRO), Canberra, carried out a land-use survey of the Leichhardt-Gilbert area, which included the Gilberton Sheet area (Perry et aI., 1964). A combined geological party from BMR and GSQ began systematic regional mapping of the Georgetown, Gilberton, Einasleigh. Clarke River, and Atherton Sheet areas in 1956. Mapping of the Gilberton Sheet area was completed in 1959 and the results recorded by White (1962, 1965). The igneous rocks and cauldron subsidence structures were described by Branch (1966a, b). Age dates of the acid igneous rocks were published by Richards et a1. (1966a, b). Isbell et a1. (1968), in explaining Sheet 7 of, the Atlas of Aus• tralian soils, gave descriptions which in effect outlined the superficial lithology of the Sheet area.

In 1955, BMR carried out airborne scintillometer surveys of the Precambrian succession in the east. Anomalies were found to coincide with granite (White & Hughes, 1957); no significant uranium mineralization was located. A Bouguer anomaly map at 1:250000 scale was published by BMR in 1969 (E54/B2-16).

PHYSIOGRAPHY

In the Gilberton Sheet area the six main physiographic units are: Oaraville Plain, Gregory Range, Gilberton Plateau, Strathpark Plain, Newcastle Range, and Chud• leigh Plateau (Fig. 1). The Claraville Plain (Twidale, 1956, 1966) is a depositional plain decreasing in height from 300 m in the east to 200 m in the. west. It is composed of soft sandstone and claystone of the late Cainozoic Wyaaba Beds, and much of it consists of thin outwash sands. At present the central and eastern parts of the plain are being dissected to expose Mesozoic sandstone and mudstone. The Gilberton Plateau covers a large area in the southeast; its height ranges from 600 m to 900 m and its surface has been tilted between to and 10 to the west, southwest, and south by late Cainozoic uplift. The plateau consists of flat-lying Mesozoic sandstone; its sandy surface is derived in part from the Mesozoic rock and in part from the products of a deep-weathering zone developed during a climatic regime different from that of the present. It is being eroded at its margins, particularly in the north and west. To the northwest, dissection is more extensive and the plateau form is lost. The Gregory Range is essentially the dissected continuation of the Gilberton Plateau. The plateau and range topography developed after uplift relative to the western half of the Sheet area in late Cainozoic time (Doutch et aI., 1970), and is due to erosion by the Gilbert and its tributaries flowing north, and to the Clara and Norman Rivers flowing west.

4 GILBERT RIVER CHUDLEIGH PLATEAU JUNTALA DOME

.... 0& "-"0~• ~ ,"" e:t> ~"SI""~,.

t.Il

1*~1Wallumbilla Formation I::':;:::"d Gilbert River Formation

~;mm\'!:.~Loth Formation I:::: : IHampstead Sandstone :;;:::::~ Paloeozoic granite

~ Precambrian E54/AJ6/il Fig. 1. Physiographic units GUbertoD 1:250 000 Sheet area. The Strathpark Plain, a sand plain in which few rivers rise, is apparently underlain by ferricrete. It may have been part of the same surface as the Gilberton Plateau before disruption by late Cainozoic tectonism. It is lower than the plateau, but higher than the Claraville Plain. Headwater erosion of the into the Strathpark Plain is exposing the quartzose sandstones beneath it. The Newcastle Range is the southern end of the range. It is developed on resistant, tightly folded Precambrian sedimentary, granitic, and metamorphic rocks. The sedimentary rocks are eroded to rough strike ridges and gullies, the granites and metamorphics to smooth undulating rises. The relief varies from 500 m to 800 m from south to north. The Chudleigh Plateau was formed by Cainozoic basalts extruded from vents in the eastern flank of the Juntala Dome east of the Gilberton Sheet area.

DRAINAGE Drainage In the Gregory Range area the courses of many rivers are controlled by faults or joints; the Norman and Woolgar Rivers are the most prominent examples. In the northwestern part of the Gilberton Plateau several ancient superimposed drainage patterns have been recognized (Doutch et al., 1970). It appears that the original meandering river flowed northwards, and its course was modified several times by faulting and tilting of blocks associated with uplift immediately east of the eastern margin of the Sheet area, the Juntala Dome being a local culmination.

STRATIGRAPHY Stratigraphy Precambrian and Palaeozoic igneous and metamorphic rock~ cropping out over wide areas in the northeast and east are part of the 'Georgetown Massif' (Hill, 1951) or the 'Georgetown Inlier' (White, 1961). Inliers of Archaean and Palaeo• zoic rocks within the Mesozoic sandstones are present in the south in the WooIgar River and Loth Creek areas. OutHers of freshwater Devonian to Carboniferous sedimentary rocks occur in the Georgetown Inlier near Gilberton homestead and in the Woolgar River and Stawell River areas. Mesozoic and Cainozoic sedimentary rocks cover the greater part of the Sheet area. Cainozoic basalt rests on Palaeozoic and Mesozoic rocks in the southeast. The stratigraphy is summarized in Tables 1-4.

ARCHAEAN?-PROTEROZOIC The oldest rocks, of possible Archaean age, consist of high-grade regional meta• morphics of the almandine-amphibolite and granulite facies. These are the Einas• leigh Metamorphics, which crop out south of Gilberton homestead, in the Percy• ville-Welfern area, and in the headwaters of the Woolgar River. They are intruded by the Proterozoic Robin Hood and Forsayth Granites, and the Upper Silurian to Lower Devonian Dumbano Granite. The metamorphic rocks exhibit retrograde and contact metamorphism which was probably produced by the intrusions.

6 Proterozoic sedimentary rocks of the Etheridge Geosyncline (White, 1961) are unconformably overlain by Mesozoic sediments near Ortona Mine. The cal• careous Bernecker Creek Formation partly intertongues with, and partly conform• ably overHes, the shale and siltstone of the Etheridge Formation. Paddys Creek Formation quartzite is preserved as a roof pendant in the Dumbano Granite. South of Gilberton homestead, foliation trends in the Einasleigh Metamor• phics are markedly discordant with bedding trends in the Proterozoic sedimentary rocks, suggesting that the two rock bodies differ in age. The relationship of the sedimentary rocks to the Croydon Ignimbrite in the Georgetown Sheet area does not provide an age for the sedimentary rocks more accurate than Lower to Middle Precambrian. Within the general framework of Australian tectonism the two rock bodies, the metamorphism, and the deformation are more likely to have been Proterozoic than Archaean (H. F. Doutch, pers. comm.). Proterozoic igneous rocks consist of the Cobbold Dolerite, intruded before or during folding of Proterozoic sediments, and the younger Croydon Ignimbrite, Forsayth Granite, and Robin Hood Granite. The Croydon Ignimbrite in the Georgetown and Croydon Sheet areas is 1400 m.y. old (Sheraton & Labonne, in prep.; cf. Richards et aI., 1966b) and in the Georgetown Sheet area the Robin Hood and Forsayth Granites range between 1000 and 1200 m.y. old (Richards et aI., op. cit.). The Croydon Ignimbrite is intruded by the Esmeralda Granite of about the same age in the Georgetown Sheet area (Branch, 1966). The granite that apparently intrudes the ignimbrite in the northwest of the Gilberton Sheet area may be part of the Esmeralda Granite. Originally, the Croydon Ignimbrite was thought to be Carboniferous, as it is lithologically similar to the Featherbed and Newcastle Range Vo1canics (Georgetown Sheet area), and appeared to have been emplaced in the same way (Branch, 1966a, b).

PALAEOZOIC

Freshwater sediments in the Woolgar and Stawel1 River areas are considered to be outHers of the Bundock Creek Beds (White, 1965; Doutch et al., 1970), whose main area of distribution is within the Broken River Embayment (Clarke River Sheet area).

The Gilberton Formation consists of freshwater sediments, containing Lep• tophloeum australe and Antiarchan fish remains, deposited in two small basins in the Precambrian Georgetown Inlier.

The Dumbano Granite of Upper Silurian to Lower Devonian age (Richards et aI., 1966a, b) intrudes the Einasleigh Metamorphics, the Etheridge Formation, and the Forsayth Granite. Two genetically related Upper Palaeozoic acid igneous complexes intruding the Dumbano Granite are exposed in the northeast (Branch, 1966a, b): The Bagstowe Ring Dyke Complex consists of ring dykes, cone sheets, and associated dyke swarms; the Butlers Igneous Complex consists of granite which intrudes an ignimbrite hood; a trachyte plug occupies the centre of the complex, but it is not exposed in the Gilberton Sheet area. The Purkin Igneous Complex may also belong to this group (Doutch et al., 1970).

7 TABLE 1. PRECAMBRIAN STRATIGRAPHY

Thickness Stratigraphic Principal Age Rock Unit' (m) Lithology Relationship References

Forsayth Granite Grey porphyritic biotite Intrudes Etheridge Forma- White, Best, & Branch Pgf granite, adamellite, grano- tion (1959) diorite White (1965) Robin Hood Granite Pink and grey hornblende• Intrudes Etheridg. and White, Best, & Branch pgr biotite, granite, adamellite, Bernecker Creek Forma• (1959) granodiorite tion, Einasleigh Metamor• White (1965) phics, and Cobbold Dol• erite

Croydon Ignimbrite Up to 365 Ignimbrite, rhyolite, rhyo• Intruded by Pzug. Intruded White & Hughes «1957) Pvc lite-porphyry by Esmeralda Granite in White, Best, & Branch .....u Georgetown Sheet area (1959) o Branch (1966a,b) ~ Cobbold Dolerite Dolerite, gabbro, amphibo• Intrudes Archaean and White, Best, & Branch Pdc lite Proterozoic rocks (1959) 00 White (1965) J:l..; Bernecket Creek 3050-4880 Calcareous sandstone and Conformably overlies and White & Hughes (1957) I Formation siltstone, calc-silicate horn• interfingers Etheridge For• White, Best, & Branch Pb feIs, marble mation. Intruded by Cob• (1959) ~ bold Dolerite and Protero• White (1965) III zoic granites ~ Paddys Creek 300-910 Quartzite, quartz phyllite Intruded by Dumbano White, Branch, & Green ~ Formation Granite (1961) ~ Pp White (1965) Etheridge Formation 4750-6090 Shale, siltstone, sandstone, Conformably underlies and White & Hughes (1957) Pe chert interfingers with Bernecker White (1965) Creek Formation. Intruded by Proterozoic dolerite and granites and by Pzu Einasleigh Granulite, gneiss, rnigma• Faulted against Protero• White, Best, & Branch Metamorphics tite, amphibolite, schist, zoic sediments and separa• (1959) Ae quartzite ted from them by meta• White (1965) morphic unconformity TABLE 2. PALAEOZOIC STRATIGRAPHY

-::sc ";:: Thickness Stratigraphic Principal ~ Age Rock Unit (m) Lithology Relationship References U o Pzu Rhyolite, quartz porphyry, Intrudes Proterozoic gran• White & Hughes (1957) N syenite, granite ite and metamorphics ::>~·0 pzug Grey and pink porphyritic Intrudes Lower Palaeozoic White (1961) granite Dumbano Granite ~ ·z Agate Creek 1220 Ignimbrite, rhyolite, ag• Unconformably overlies White & Hughes (1957) ::g< Volcanics glomerate, basalt; minor Proterozoic rocks. Basalt White, Best, & Branch Pa sandstone and shale member unconformably (1959) ~~ overlies Gilberton Forma• Hutchinson. (1965) ~le tion

Bagstowe Ring Pink microadameIIite, pink Intrudes Lower Palaeozoic Branch (1966a,b) Dyke Complex and grey rhyolite, andesite Dumbano Granite 8~ CPg (a to d) microgranodiorite ffi •..• Butlers Igneous Ignimbrite, granite Intrudes Lower Palaeozoic Branch (1959, 1966a,b) ~~ Dumbano Granite \0 Zj:l., Complex o. CPb (a, b) Purkin Igneous Granite? Intrudes Lower Palaeozoic Doutch et al. (1970) Complex Dumbano Granite? 5g CPp

~ Gilberton Formation 60-210 (/) Arkose, conglomerate, Unconformably overlies White & Hughes (1957) DCg shale and faulted against Pro• White (1957) ~::> terozoic Bemecker Creek ~ Formation. Unconformably ~~ overlain by Eulo Queen Group and Agate Creek ~~ Volcanics ~gj Bundock Creek 290 Arkose, lithic sandstone Unconformably overlies White and Hughes (1957) A~ Formation and conglomerate, siltstone Dumbano Granite and White (1965) ::) DCb Einasleigh Metamorphics

~~ Dumbano Granite Grey biotite granite, adam• Intrudes Einasleigh Meta• White, Best, & Branch SDd eIIite, granodiorite, granite morphics, Etheridge For• (1959) gneiss mation and Forsayth White (1965) ::>~~j~ Granite. Intruded by Bag• SA stowe Ring Complex ti.l~ TABLE 3. MESOZOIC AND CAINOZOIC STRATIGRAPHY.-(cont.)

... Jh fIl thenotArchaean?inConformablyRestsunconformablysiltstone,siltstone;penetratedcoalsandstone,andsandstonesilt.Reynoldsoverliesonrocks;QuartzoseRockQuartzoseinun(J);(1960)UnitdLithologyer clayey(m)RelationshipliUpHampsteadConformablyPalaeowic,MesowicNeedhamVinewest13)Smart30-45ReferencesePrincipaltos 90sandstone(1966,100+45-60conformablyet al.etsandstonesProterozoicSandstone.1970)Sandstone(1971)al.stone,conglomerate;(1971,overliesstone,BaseclayeyBMRandconglomerate,p.ThicknessStratigraphicconglomerateGilbertonsandstoneminorbores minorNoclay-2sandstoneclay- and unconformably overlies Smart et a!. (1971) ...• ·Hampstead Age0 U Mesowic(sectionJ Julonly)JueSandstone.SandstoneGroup Palaeozoic,Doutch(J)Archaean?et al.Proterowicrocks(1970) and - .Loth Formation ~ Eulo Queen Undifferentiated • both belong to Eulo Queen Group TABLE 4. CAINOZOIC STRATIGRAPHY

Thickness Stratigraphic Principal Age Rock Unit (m) Lithology Relationship References ~ Modern alluvium 0-3 Quartzose sand, silt and Doutch et al. (1970) uffi Qra clay Floodout alluvium 0-3 Yellow quartzose sand Doutch et al. (1970) § Qro ::I:l

WyaabaBeds 30 Clayey quartzose sand and Rests unconformably on Doutch et. al. (1970, 1972) ~~ Czy sandstone, sandy claystone Mesozoic rocks Chudleigh Basalt 30 Olivine basalt Infills valleys in Mesozoic Twidale (1956) 00~9 Czc and older rocks Wyatt & Webb (1970) ::l::l:l .... ll-o .... Czs 0-3 Colluvial and outwash Rests on Td and Tf also on Doutch'et al. (1970) sand and silt Mesozoic and older units

~>o Tf 0-5 Ferruginous lithified gravel Developed on quartzose Doutch et al. (1970) .®~ (ferricrete ) Mesozoic sandstones Td Lithified soil and colluvial Formed on Mesozoic rocks ;:J~!9 Up to 15 Doutch et al. (1970) detritus (duricrust) ~g

Cl) Wallumbilla Up to 140 Mudstone, minor glaucon• Conformably overlies Gil• Reynolds (1960) Formation itic sandMone,1imeMone bert River Formation Dickins (1960) 5 KIu ~ Gilbert River Up to 45 Quartzose sandstone and Conformably underlies Laing & Power (1959a,b) Formation conglomerate, minor silt• Wallumbilla Formation, Reynolds (1960) ~ JKg stone conformably overlies Loth Doutch et al. (1970) U Formation Smart et al. (1971) The Agate Creek Volcanics are preserved in a down-faulted basin in the north, near Agate Creek. A thin basal sedimentary unit contains Lower Permian Glossop• teris sp., Gangamopteris sp., and Noeggerathiopsis sp. The ages of acid igneous intrusions (pzu & Pzug) are uncertain, but thliY intrude Precambrian and Lower Palaeozoic rocks. The granite (pzug) could be correlated with the Elizabeth Creek and Granites of the Einasleigh Sheet area to the northeast, and the rhyolite porphyry (Pzu) with the Butlers and Bagstowe igneous complexes (White, 1962).

MESOZOIC

The Mesozoic sequence is mainly arenaceous, with argillaceous sediments near the top. The whole arenaceous sequence was originally describd as Gilbert River For• mation by Reynolds (1960) and White (1962, 1965). However, more detailed work (Doutch et aI., 1970; Smart et al., 1971) has shown that only the top of the arenitic sequence in the Gilberton Sheet area is equivalent to the Gilbert River Formation as originally defined by Laing & Power (1959a). Below it comes the Eulo Queen Group, and below that, subsurface, a further Jurassic sequence. All the sandstone units have been formally defined or revised by Smart et al. (1971), and their relationships with other units in the Carpentaria and Eromanga Basins are discussed by Doutch et al. (1970). The Eulo Queen Group is confined to a depression in basement rocks called the Millungera Depression (Doutch, et aI., 1970), the eastern margin of which is exposed in the Gilberton Sheet area. The Middle Park Structure (Fig. 2) appears to have formed the eastern edge of the Depression during the deposition of the earlier Mesozoic sediments, but subsequent deposition extended farther east, though the margin of deposition of both the Eulo Queen Group and the Gilbert River Formation remained near the eastern edge of the Sheet area. In outcrop the Hampstead Sandstone rests unconformably on an eroded surface of Precambrian and Palaeozoic rocks. In BMR Gilberton No. 2 well in the southwest, it is underlain by at least 60 m of similar sandstone (1) (Needham et aI., 1971), whose age on palynological evidence is Upper Jurassic (Burger, in Needham et aI., 1971). The relationships of this underlying sandstone to the Hampstead Sandstone and to units in the northern Eromanga Basin are discussed by Smart (in prep.). The Loth Formation is distinguished by its dominantly clayey character. Differential weathering and erosion have produced a marked topographic break at the base and top of the formation. The base of the Gilbert River Formation is generally conglomeratic; in the Sheet area and over much of the Carpentaria Basin it commonly rests directly on basement. The formation represents the maximum extension of the quartzose sand• stone sedimentation, but the presence of a regional unconformity between it and the Eulo Queen Group (cf. Vine, 1966) has yet to be proved. The upper part of the Gilbert River Formation contains an estuarine-marine fauna representing the onset of marine conditions which continued during the deposition of the dominantly argillaceous Lower Cretaceous sequence. Only the lowest of the Cretaceous units, the Wallumbilla Formation of the Rolling Downs

12 Group (Vine et aI., 1967) is present, in the southwest. This was originally called Roma Formation by Reynolds (1960).

CAINOZOIC Previous work on the Cainozoic rocks in the area was essentially geomorphological (Twidale, 1966). The first Iithological subdivision was made by Reynolds (1960), and Doutch et al. (1970, 1972) subdivided them in more detail. The unit of partly lithified soil and colluvium ('duricrust'-Td) is ferruginized in some areas, particularly in its upper part. It is uncertain to what extent this was due to superimposition of deep weathering or lateritization. In the west, a ferricrete unit (Tf) has been exposed through erosion by the Saxby River system. It may be the same age as a lateritic bed present over wide areas to the north and northwest (Doutch et al.. 1970. 1972). UnconsoIidated sand and silt (Czs) overlying the 'duricrust' unit have been grouped with other sand deposits of broadly similar stratigraphic position in the northwest and south. The unit is partly coHuvial and partly outwash; the bulk of the unit on the Strathpark Plain and Gilberton Plateau probably developed in situ, while much of it in areas bordering the range in the north and south is outwash, for example around Clara River and Hampstead Creek. The Chudleigh Basalt was extruded from vents situated immediately east of the Sheet boundary in the Clarke River Sheet area, and flowed down old valleys, where it has been preserved. The sequence of clayey quartzose sand and sandstone of the western part of the Sheet area was originally called Lynd Formation (White, 1962) but subsequent work has shown that it belongs to the Wyaaba Beds (Doutch et aI., 1972; Smart et aI., 1972). It is the southern part of an extensive sheet of late Cainozoic sedi• ments which extends for several hundred kilometres north along the western side of Cape York Peninsula as a result of erosion that followed uplift of the Gulf• watershed (Doutch, in prep.).

STRucruRE AND TECTONICS (by H. F. Doutch) The structural history of the area, which spans at least 1800 m.y. can be explained in terms of the four main episodes (see Fig. 2); in this time interval other episodes such as late Precambrian warping most probably occurred, but the evidence either has since been destroyed or remains unrecognized.

The Precambrian Craton The Croydon Ignimbrite-Esmeralda Granite complex was emplaced north of the Sheet area in sediments of the Etheridge GeosyncIine, 1400 m.y. ago (Richards et aI., 1966b; Sheraton & Labonne, in prep.). Whether this happened at the same time as folding, faulting, and metamorphism, or later, is unknown. White (1965) found that faulting foHowed folding; he suggested that deformation of the geosyn• cline was controlled by a nucleus of Einasleigh Metamorphics, around which bedding trends and fold axes in the geosyncline are disposed more or less con• centrically. The Cobbold Dolerite may have been intruded during folding.

13 M

Cz M

-?--?--?-

o 10 20 km ~ 1 r--' Cl o 10 M M

CAINOZOIC Deformotion 01 Eromango Bosin --- Pre-Mesozoic fault

~ Late Tertiary and Quaternary sand PALAEOZOIC Modilicotions 01 Precambrlon croton

l;f~c}/'1Chudleigh .Basalt rpz~gJ Late Polaeozolc granite intrusions Fault-block ftlt and generali.18d dip of Mesaraic strata ~ LatesedimentaryPalaeozoicrocksvolcanic and

--- Fault,·observed, Cainozok displacement ctJrtoin ~Pgg Ring fractures and cauldron campl.x(JS ~ ~P9bPgp . 10:~ Foult, flexure Or discontinuity} from sections, Gilberton Basin and sim,Yar relics structural contours f(i.~~;~;1 11>~:I Dumbano Granite Diu DOwnthrown and uplifted sides of fault PRECAMBRIAN Creation 01 Precombrlon croton Lineament, including hinge lines, possible -.- faults or joints m Post-deformafianal granite K~ Joints I:~~ivlSyn-deformational aCid volcanics MESOZOIC Downworping and deposition, Eromongo Basin ~ beddingSedimentarytrends,rocks,EtherfdqedolerfteGeosynclin/land o Mesazaic sedimentary rocks I"Ae;1 Metamorphics and faliatian tr/lnds Fig. 2. Structural and tectonic map.

The Einasleigh Metamorphics have not been dated. The general pattern of Australian tectonic history suggests that both the rocks affected by metamorphism and the actual metamorphic event are more likely to· be of Proterozoic than Archaean age; that is, the rocks may have belonged to the Etheridge Geosyncline ratherthan constituting a nucleus to it. About 1200 m.y. ago the Forsayth Granite was also intruded into the Etheridge Geosyncline. The Robin Hood Granite, although dated at 1120 m.y. (Richards et al., 1966b), may have been part of the same event. Bedding and

14 foliation trends appear to have acted as a structural control during the roughly con• cordant intrusion of the Robin Hood Granite. These granites and all older rocks make up a Precambrian craton.

Palaeozoic modification of the craton Between 700 and 850 m.y. later, the Dumbano Granite was intruded into the craton in Silurian to Devonian time. The intrusion reflects climatic episodes of orogenic tectonism which deformed the Lachlan Geosyncline in southeast . Isotopic dates determined from rocks in adjacent areas also indicate a Siluro• Devonian age (Richards et al., 1966b), as well as giving Proterozoic ages; the Dumbano Granite may thus be only one aspect of an event which mildly deformed most of the craton. The influence of tectonism continued farther south. The Devonian-Carbon• iferous Gilberton Basin is similar in a general way to the Bundock and Burdekin Basins to the east and to other post-orogenic basins of this period associated with the stabilization of the Lachlan Geosyncline. The contents of the basin were moderately deformed probably at about the same time as the orogeny which de• formed the Hodgkinson Basin to the northeast. In Carboniferous and Permian time tectonism related to events to the south was replaced by igneous activity which followed Hodgkinson Basin deformation, characterized in this Sheet area by the Bagstowe Ring Dyke Complex and Butlers Igneous Complex. Branch (1966b) discussed the rocks and structures of the com• plexes. Other Upper Palaeozoic igneous rocks in the Sheet area are probably dif• ferent aspects of the same event.

Mesozoic downwarping and sedimentary basin deposition Downwarping of the modified craton probably started locally in Jurassic time, although preserved Permo- Triassic rocks of the Galilee Basin occur not far to the south. In this Sheet area older Jurassic sediments of the Eromanga Basin were deposited in the Millungera Depression. The Middle Park Structure marks the eastern margin of the Depression before onset of Eulo Group deposition; this structure probably has a Palaeozoic or Precambrian origin, and was reactivated in the Cainozoic. Younger sedimentation in the basin in the Sheet area was probably controlled by sea level fluctuations rather than downwarping.

Cainozoic deformation Late Tertiary movements uplifted the eastern margin of the Carpentaria and Era• manga Basins before the probably co-genetic Pliocene? Chudleigh Basalt (Doutch et al., 1970) was extruded, and resulted in block-faulting of Mesozoic rocks in the Sheet area. Uplift was episodic: ancient drainage systems north of the Gilberton Plateau were disrupted at least twice as the blocks developed (Doutch et al., op. cit.). Uplift was greatest on what is now the northeastern side of the Gilberton Plateau, where the Juntala Dome was formed. The plateau consists of a jumble of fault blocks which tilt and radiate from northwest to southwest away from the dome (Fig. 2); tilt is rarely more than 10• Boundaries between blocks may be hinges

lS (some of them shown as lineaments on the map and in Fig. 2), flexures (such as the Purkin Monocline), or normal faults of small displacement (such as the Nor• man River Fault). At the Middle Park Structure, sections and structural contours indicate down• faulting of the whole of the western part of the Sheet area, where they also demon• strate shallow southwesterly dips in the Mesozoic rocks and the presence of a long discontinuity, the Woodstock Structure. The Middle Park Structure, together with lineaments and faults paralleling it in the east, is a northern extension of the Cork Fault and Weatherby Structure of the Eromanga Basin. This system was partly produced by differential sagging in the basin during and after sedimentation;. the southern part of the system appears to be the junction between basements con• sisting of Precambrian craton to the west and Palaeozoic geosyncline to the east, a junction which underlies the Juntala Dome in the Sheet area. The Woodstock Structure may be either a fault or a flexure and is part of the Euroka Arch, which is a complex feature forming the present structural boundary between the Carpentaria and Eromanga Basins (Doutch et aI., 1970). The most strongly developed joint sets in Mesozoic rocks in the Sheet area are concentrated at the eastern end of the arch.

The Late Tertiary uplift caused faulting of the pre-Mesozoic rocks in the northeast, and they were probably also affected by rejuvenation of Palaeozoic and Precambrian structures. It resulted in erosion which exposed the cratonic rocks known as the Georgetown Inlier. Bouguer anomaly contours relate to the rocks and structures of the Inlier rather than to its younger cover. The uplift was related to similar events which created the ancestral Great Dividing Range of eastern Aus• tralia, and was contemporaneous with the beginning of the orogenio uplift of the highlands of New Guinea.

GEOLOGICAL HISTORY The geological history of the Gilberton Sheet area is summarized in Figure 3.

ECONOMIC GEOLOGY The Gilberton Sheet area includes the goldfields of Woolgar and Percyville. Appreciable amounts of copper and lead, and a little silver, zinc, tungsten, and bismuth have also been produced.

Gold

The Woolgar Goldfield covers an area of 2850 km 2, but most of the mines are contained within an area of 1000 km2 near the Woolgar River on the south• western edge of the Gregory Range in the southern part of the Sheet area. The most comprehensive description of the field was provided by Saint-Smith (1922). The gold reefs are in granite and Archaean? metamorphics, both of which are intruded by dolerite ('diorite') and pegmatite dykes. Saint-Smith described the reefs as occupying 'shrinkage lines along the margins of pegmatitic granite dykes'. Reefs also occur in shears within the dolerite (amphibolite) dykes. The reefs ranged from 3 to 210 m in length (average 60 m); they were 0.6 m wide

16 W E I I 9(1) I I GEOLOGICAL HISTORY ~i5 Czy JKg Tf ~. ----- 7 CAINOZOIC .....'" '.' I "~ z Development of 'duricrust' (rd) and ferricrete (rf); upllff with 2'<3w7·-> { r I...•••.....~ 'f:.'" Gilberton,,'..Plafeau"".~ """+P Juntala Dome associated widespread block-faulflnll Extrusion of basalts (Crc) In eost Erosion topres;ni form; depaslflan of clayey sands (Cry) in west

6 MESOZOIC ::3~ 60._ : •• -: •• J: . ~~!,l", R'"Klu .....~ :j~Kg••.'Jue/ ;I..~ pHPz :=J Formation 01 Mi//ungera Depression on(/ deposition of ferresfial ::;; Units of Mlllunqera sed/ments (J 8Jue) Extension 01 sedimentation and deposition { Gregory Range Depression 8agstowe Ring of Jurassic-Crefaceous sands (JKg) Onset of marine conditions Dyke Complex upper port of JKq followed by Cretaceous. marine muds (Klu) Pg

5 CARBONIFEROUS TO PERMIAN I-'" , Z Major faulting and ring fracturing accompanyingintrusion of >W rhyolife ring dykes, conesheets and associated high level granites W (Pg) Extrusion of lovas (Po) Also probably acid intrusions (pzu) U and (pzuq) w~ Gilberton Basin , :J I 4 EARLY TO MID PALAEOZOIC ~ Intrusion of Dvrnbano Granite (SOd) Formation 01 Gi/berton and Bundock Basins1 deposition of fresh water sedimenls with fish and plant fossIls (DCq/OCb) and then deformation of the basins Gilbert River !?vc : lee 3 MID TO LATE PROTEROZOIC

Intrusion of dolerifs (Edc) and folding of Proterozolc s~dlmenlsi ignimbrite extrusion (Eve) Intrusion of granites (Pgr, Pgl)

2 EARLY PROTEROZOIC Formation of basins in Archaeon ? basement, probably by faultingj deposition of si/Is and clays (Ee), calcareous s/If(eb}, and sond (ep) of the Efherldqe Geosyncllne .

I ARCHAEAN ? High grade regional metamorphism of 6ar/iesl rocks fo omphibolite itJpies (Ae?J --~~-~------~----~- I~------~---~~--~~---~------~-~-- - -- M? - _~ E54/AI6~12 Fig. 3. Geological histOl"Y.

and worked to an average depth of 24 m, about the depth of the water table. The reefs generally dipped from 800 to 850• Some of the gold ore contained lead, copper, and manganese minerals. The main production was obtained from the Woolgar Goldfield between 1880 and 1887, when 567 kg (15000 oz) of gold was won, including 150 kg (4000 oz) of alluvial gold. Production declined after this period, and up to the time of Saint-Smith's inspection in 1922 only 113 kg (3000 00) of gold, averaging 50 g/tonne (I! oz per ton), were produced. The main producing mines were the Perseverance-Try Again, Soapspar, and Mowbray. The Soapspar and Redjacket mines were the only mines working in 1958. The Percyville Goldfield is situated on the Percy River in the northern part of the Sheet area. The gold occurs in reefs near the contact of Precambrian meta• morphics with granite, both of which have been intruded by pegmatite and rhyo• lite dykes. Ball (1915) described the lodes as generally siliceous. The gold reefs average 0.6 m in width and some are nearly 0.5 km long. Most workings do not

17 penetrate below the oxidized zone, which is probably 30-45 m deep; the deepest workings extended to 152 m in the Union Mine. The gold ore contained appreciable amounts of lead, silver, zinc, and copper; one assay at the 30 m level of the Home• ward Bound Mines was 560 g/tonne (15! oz per ton) Ag, 45 g/tonne (It oz per ton) Au, 13% Pb, 2% Cu. Total production from 1912 to 1917 on the Percyville Goldfield was 2080 tonnes of ore, which yielded 150 kg (3950 oz) gold, 400 kg (10334 oz) silver, and 90 tonnes copper; 13 tonnes of lead were won in 1912. The largest production from anyone mine was 105 kg (2800 oz) of gold from the Union Mine. The primary ore averaged 20 to 25 percent copper and 220 to 260 g/tonne (6 to 7 oz per ton) of gold, with exceptional small rich patches containing 3700 g/tonne (100 oz per tonne) gold. Gold has also been mined from quartz reefs in the Proterozoic granite at Mount Hogan in the headwaters of Granite Creek in the northeast. No information is available on the size of the reefs. Jack and Etheridge (1892) recorded produc• tion of 170 kg (4500 oz) of gold averaging 65 g/tonne (U oz per ton) from 1885 to 1890. Gold averaging 75 to 110 g/tonne (2 to 3 oz per ton) was mined at Mount Moran, 3 km north of Ortona copper mine near the northern boundary of the Sheet area. Gold was obtained from quartz veins in weathered and leached dolerite dykes between depths of 15 ID and 90 m, below a cover of Cretaceous sediments. The Mount Moran Mine should not be confused with Mount Moran, a prominent peak in the Mount Hogan goldfield.

Copper The Ortona copper mine was the main producer of copper in the Gilberton Sheet area. The mine is on the Percy River some 6 km from its junction with the Gilbert River in the northern part of the Sheet. Ball (1915) described the mine, which ceased production later. The reefs fill fissures or contraction joints in 'diorite' dykes and have a maximum width of 4.5 m and a maximum length of 182 m. The ore consisted of quartz and hematite, with copper, silver, and gold. The mine was worked to a depth of 42 m in the oxidized zone. The secondary ore averaged about 35% copper. The total production was about 1780 tonnes of ore averaging 25% copper. The Eight Mile copper-bearing area is near the junction of Eight Mile Creek and the Gilbert River, 13 km west of Gilberton homestead. Ball (1915) described the copper lodes as occupying fissures in steeply dipping Proterozoic slate and lime• stone intruded by 'diorite' dykes and stocks and rhyolite dykes; the copper was probably introduced by the 'diorite'. There are three main lodes, which are 30 m to 1 km long (averaging 300 m), and averaging 3 m wide and 15 m deep. About 100 tonnes of ore averaging 25-35% copper with 370 to 445 g/tonne (10 to 12 oz) silver and 11 g/tonne (7 dwt per ton) of gold have been won from the Eight Mile area. The Twelve Mile copper-bearing area is about 20 km west of Gilberton home• stead near the junction of 12 Mile Creek and the Gilbert River. The lodes are in steeply dipping east-trending Proterozoic slate near an intrusion of dolerite. One working consists of a 15 m shaft sunk on a quartz-veined ferruginous clayey slate.

18 The lode is about 45 m long and 18 m wide. Ball (1915) recorded 30 tonnes of 5% copper ore containing dense limonite, disseminated malachite, cuprite, and glance.

Other Metals Tungsten and bismuth have been obtained from an area locally known as the '8 mile Percyville'. This locality was first recorded by Jensen (1919) and later described by Morton (1945). The ore-bearing quartz veins are 5 to 30 cm thick; they are mainly in dolerite ('diorite') that intrudes steeply dipping east-trending Precambrian schist. The workings are generally shallow and reach a maximum depth of 9 m, scattered over a length of 500 m. Seven tonnes of scheelite concen• trate (65 to 70% WOg) were mined from 1918 to 1937 and t tonne bismuth con• centrate between 1918 and 1919. Alluvial bismuth and tantalum are recorded by Ball (1915) as having been obtained in small quantities at Dividend Gully near PercyvilIe. Cobalt in the form of gersdorffite (an arseno-sulphide of nickel, cobalt, and iron) was found in 1957 in a 10 cm vein in a 1.2 m pit near the Ortona copper workings. Ridgeway (1945) recorded agate in workings near the headwaters of Agate Creek in the north of the Sheet area. The agate occurs in veins and amygdales of the Permian Agate Creek Volcanics. Reserves of the crude mineral are estimated at 27 tonnes per vertical metre. Hutchinson (1965) provided a prospectors' guide to the area. Coal has been reported from several bores in the area. BMR Scout Hole Gilberton No. 2 (Needham et aI., 1971) penetrated carbonaceous streaks and bands within the Hampstead Sandstone and thin coal seams within the underlying Mesozoic sandstone.

Water

Most streams flow only in the wet season. In the western half of the Sheet area, underground water can be drawn from the Mesozoic sandstones, but few deep bores have been drilled. Water for cattle is obtained mainly from river waterholes and shallow bores in alluvium. In the Gilberton Plateau-Gregory Range area the Mesozoic sandstones are geuerally dry and a few tanks have been dug. In the northeast in the Precambrian and Palaeozoic outcrop areas, water supplies are derived mainly from river waterholes, particularly in the Gilbert River. Reynolds (1960) discussed the hydrology of the Gilberton area. Ground• water is obtained from the Mesozoic sandstones, mainly from the Gilbert River Formation and the Hampstead Sandstone (Table 4), and smaller supplies from the Loth Formation. nores immediately west of the Gregory Range, in the Strath• park Plain, are spudded into the Loth Formation up-dip of the water table, and derive their supplies from the underlying Hampstead Sandstone. Farther west, artesian bores produced from either or both the Gilbert River Formation and the Hampstead Sandstone, aIid tn~~y have considerable flows. Many bores in the west do not penetiate the Hampstead Sandstone, as ade• quate supplies are available from the Gilbert River Formation and to a lesser extent 0 *43332372239421022619°52'8-142°48'E19°46'S-142"33'E19°48'8-142°41'E19°51'S-142°39'E19°59'S-142(m)Aquifers19°32'S-142°34'E19°27'8-1422553082?(m)(m)MlKgKluJKg+M5127?DepthFormationAStatusS23451392702801581915 247Total1843 (m)Lat.Litres/&Elevation59.356.316.0Long.234 Tops208°48'E°32'E779 47 Sec.80 Initial16.5S FlowTABLEMPLES OF ARTESIAN AND SUB-ARTESIAN BORES N 4149434943454346 Number ISWC M=MesowicS* = Sub-ArtesianGamma-Ray*4339 rocks logged older than Gilbert River Formation (JKg) A=4148 Artesian Name or the Loth Formation. Bore No. 4149 has an artesian flow of over 4! million litres per day, from four aquifers. The main flow is probably from the two highest aquifers, both within the Gilbert River Formation; the others appear to be in the Loth Fortllation. The temperature of the water from the Mesozoic sandstones ranges from 35' to 40' C. Water from the Gilbert River Formation often has an abnormally high fluorine content (Ogilvie, 1955); the fluorine content of water in bores in the southwest ranges between 0.5 and 1.0 ppm (Doutch et al., 1970). Small supplies of saline water are available in some places from the Wyaaba Beds, but are not often used in this area, as the Mesozoic aquifers are fairly shallow. Springs occur in the sandy forest country west of the Gregory Range. Some springs immediately west of the outcrop of the Gilbert River Formation are apparently due to water from the Gilbert River Formation breaking through the thin mudstone of the Wallumbilla Formation. There are some small springs on the margins of the Gregory Range, e.g., at Woolgar. Reynolds (1960) reports springs fed by water from the Mesozoic sandstones; others are in alluvium or outwash sands, and a few derive their supply from fractured basement rocks.

21 -

BIBLIOGRAPHY BALL, L. C., 1915-The Etheridge Mineral Field. Geol. Surv. Qld Publ. 245. BRANCH, C. D., 1959-Progress report on Upper Palaeozoic intrusions controlled by ring fractures near Kidston, . Bur. Miner. Resour. Aust. Rec. 1959/104 (unpubl.). BRANCH,C. D., 1966a-The structure and evolution of the volcanic cauldrons, ring complexes and associated granites of the Georgetown Inlier, Queensland. N,ature, 209, (5023), 606-7. BRANCH, C. D., 1966b-Volcanic cauldrons, ring complexes, and associated granites of the Georgetown Inlier, Queensland. Bur. Miner. Resour. Aust. Bull. 76. BRANCH,C. D., 1969-Phanerozoic volcanic history of northern Queensland. Geol. Soc. Aust. spec. PubI. No. 2, 177-182. BRYAN, W. H., 1932-Early Palaeozoic earth movements in Australia. Aust. Ass. Adv. Sci. Rep. 21, 90. BRYAN,W. H., & JONES, O. A., 1944-A revised glossary of Queensland Stratigraphy. Unlv. Qld Dep. Geol. Pap. 2(11). BRYAN,W. H., & JONES,O. A., 1946-The geological history of Queensland. Ibid., 2(12). CAMERON, W. E., 1900-The Etheridge and Gilbert Mineral Fields. Geol. Surv. Qld Publ. 151. COTTON, L. A., 1930-An outline and suggested correlation of the Precambrian formations of Australia. J. Ray. Soc. N.S.W., 64, 10-64. DAINTREE, R., 1870-Report by Mr R. Daintree, late Government Geologist, North Queens• land, on the Ravenswood, Mount Wyatt and Cape River Gold Fields. V & P. Legis. Ass. 3rd Sess. 1870, 1. DAINTREE,R., 1872-Notes on the geology of the colony of Queensland. Quartz J. Geol. Soc. Lond., 28, 271-317. DAVID,T. W. E., 1932-EXPLANATORY NOTESTO ACCOMPANYA NEW GEOLOGICALMAP OF TIlE COMMONWEALTHOF AUSTRALIA.Sydney, Australas. Medical Publishing Co. Ltd. DAVID, T. W. E. (ed. BROWN, W. R.), 1950-TIIE GEOLOGYOF THE COMMONWEALTIIOF AUSTRALIA.London, Arnold. DICKINS, J. M., 1960-Cretaceous marine macrofossils from the Great Artesian Basin in Queensland. Bur. Miner. Resour. Aust. Rec. 1960/69 (unpubl.). DOUTCH, H. F., in prep.-Late Cainozoic tectonics and geomorpho1ogy of southern New Guinea and Cape York Peninsula. Bur. Miner. Resour. Aust. Rec. (unpubl.). DOUTCH,H. F., INGRAM,J. A., SMART,J., & GRIMES, K. G., 1970-Progress report on geology of the southern Carpentaria Basin. Bur. Miner. Resour. Aust. Rec. 1970/39 (unpubl.). DOUTCH,H. F., SMART,J., GRlMES, K. G., NEEDHAM,R. S., & SIMPSON, C. J., 1972-Progress report on geology of the central Carpentaria Basin. Bur. Miner. Resour. Aust. Rec. 1972/ 64 (unpubl.). DUNSTAN,B., 1913-Queensland mineral index and guide. Geol. Surv. Qld Publ. 241. GRIMES, K. G., & SMART,J., 1970-Shallow stratigraphic drilling, southern Carpentaria Basin, 1969. Bur. Miner. Resour. Aust. Rec. 1970/38 (unpubl.). HILL, D., 1951-Geology: in Handbook for Queensland. Aust. Ass. Adv. Sci., 13-24. HILLS, E. S., 1936-Records and descriptions of some Australian Devonian fishes. Proc. Ray. Soc. Vie., 48(11),161-71. HILLS, E. S., 1946-Some aspects of the tectonics of Australia. J. Ray. Soc. N.S.W., 79,67-91. HUTCHINSON,G. H., 1965-A prospectors' guide to agate at Agate Creek. Qld Govt Min. J., 86, 517-9. ISBELL, R. F., WEBB, A. A., & MURTHA,G. G., 1968-Atlas of Australian soils. Sheet 7 North Queensland. With explanatory data. CSIRO and Melbourne Univ. Press, Melbourne. JACK,R. L., 1887-Geological observations in North Queensland. Geol. Surv. Qld Publ. 35. JACK, R. L., & ETHERIDGE,R. Jnr, 1892-THE GEOLOGYAND PALAEONTOLOGYOF QUEENSLAND ANDNEW GUINEA.Brisbane, Govt Printer; and London, Dulau. JENSEN, H. I., 1919-The scheelite field near Percyville. Qld Govt Min. J., 20 (224), 12. JENSEN, H. I., 1920-The geology and mineral prospects and future of North Queensland. Qld geogr. J. 34-5, 23-36. JENSEN. H. I., 1923-The geology of the Cairns Hinterland and other parts of North Queens• land. Geol. Surv. Qld Pub/. 274. LAING, A. C. M., & POWER, P. E., 1959a-New names in Queensland stratigraphy. Aust. Oil Gas J.; 5(8), 35-6. LAING,A. C. M., & POWER, P. E., 1959b-Idem (Part 2). Ibid., 5(9), 28. MAITLAND,A. G., 1898-The delineation of the artesian water area north of Hughenden. Geol. Surv. Qld. Publ. 121. MARKS, E. 0., 1911-The Oaks and eastern portion of the Etheridge Goldfield. Geol. Surv. Qld Publ. 234. MORTON, C. C., 1945-Scheelite, Percyville district. Qld Govt Min. J., 46(523), 142-3. NEEDHAM,R. S., SMART,1., GRIMES, K. G., & DoUTCH, H. F., 1971-Stratigraphic driIling in the southern Carpentaria Basin, 1970. Bur. Miner. Resour. Aust. Rec. 1971/142 (un• publ.) . 22 OGILVIE,C., 1955-The hydrology of the Queensland portion of the Great Australian Artesian Basin. Appendix H in Artesian Water Supplies in Queensland. Co-ord. Gen. Public Works, pari. Pap. A. 56-1955. PARKINSON,W. D., & MULDER,J. M., 1956-Preliminary report on airborne scintillograph survey at Chillagoe and Einasleigh-Gilberton, Queensland. Bur. Miner. Resour. Aust. Rec. 1956/63 (unpubl.). PERRY,R. A., SLEEMAN,J. R., TWIDALE,C. R., PRICHARD,C. E., SLAlYER,R. 0., LAZARIDES, M., & COLLlNS,F. H., 1964--General report on lands of the Leichhardt-Gilberton area, Queensland, 1953-54. CSIRO, Land Res. Ser. 11. QLDDEP. MIN., 1932-The Woolgar Goldfield. Prospects for miner and millowner. Qld Govt Min. J., 33 (391),386-9. REIn, J. H., 1929-Marginal formations of the Great Artesian Basin in Queensland; in Rep. Fifth Interstate Conf. Artesian Water. Sydney, Govt Printer. REYNOLDS,M. A., 1960--Mesozoic and younger sediments of the Georgetown and Gilberton 4-mile Sheet areas, Queensland. Bur. Miner. Resour. Aust. Rec. 1960/68 (unpubl.). RICHARDS,1. R., WHITE,O. A., WEBB,A. W., & BRANCH,C. D., 1966a-Chronology of the acid igneous rocks of North Queensland, Australia. Earth planet. Sci. Lett., I (1966), 107-9. RICHARDS,J. R., WHITE,O. A., WEBB,A. W., & BRANCH,C. D., 1966b-Isotopic ages of acid igneous rocks in the Cairns Hinterland, north Queensland. Bur. Miner. Resour. Aust. Bull. 88. RIDGEWAY,1. E., 1945-Re agate-Agate Creek, Percyville. Qld Govt Min. J., 46(528), 299-300. SAINT-SMITH,E. c., 1922-Woolgar Goldfield. Qld Govt Min. J., 23(261), 51-5; 23(262), 95-8. SHERATON,J. W., & LABONNE,B., in prep.-Geochemistry of Australian granites Part I: North Queensland. Progress report. Bur. Miner. Resour. Aust. Rec. (unpubl.). SMART,J., in prep.-Stratigraphic cOITelationsin the southern Carpentari

24