Survey conducted by the Commonwealth Government or State/Territory Geological Survey (or equivalent) collecting airborne geophysical data

The Cooper Basin is a Late Carboniferous-Middle Triassic intracratonic basin in north-eastern South Australia and south-western Queensland. The basin is Australia's premier onshore hydrocarbon producing province and is nationally significant, providing domestic gas for the East Coast Gas Market. Exploration activity in region is experiencing a revival with numerous explorers pursuing newly identified unconventional hydrocarbon plays, however the undiscovered unconventional gas resources in the basin remains poorly defined. This study reviews the hydrocarbon prospectivity of the Cooper Basin, with a focus on unconventional gas resources. Regional basin architecture is characterised through compilation and integration of formation tops, structure surfaces and isopach maps, indicating that the wider extent of the Toolachee and Patchawarra formations may extend further north in Queensland than previously mapped. Source distribution and quality are reviewed demonstrating the abundance of source material across the whole basin. The Toolachee and Patchawarra formations are the richest source units, however organic rich rocks areTOC is also present in the Nappamerri, Daralingie and Epsilon formations, and the Roseneath and Murteree shales. Petroleum systems modelling, incorporating new compositional kinetics, source quality and TOC maps, highlights the variability in burial, and thermal and hydrocarbon generation histories between depocentres. Although initial hydrocarbon generation occurred in the Permian, peak oil and gas expulsion across the basin occurred in the Cretaceous. Pressure distribution estimates are made for all major depocentres to better characterise variation in overpressure distribution. The Cooper Basin hosts a range of unconventional gas plays types, including the very extensive basin-centred gas play and tight gas accumulations in the Gidgealpa Group, deep coal seam gas associated with the Patchawarra and Toolachee formations, as well as the less-extensive shale gas plays in the Murteree and Roseneath sShales. However the overlapping nature of these plays makes it more convenient to consider them within the context of a single combined Gidgealpa Group unconventional gas play. The possible extent of the combined Gidgealpa Group gas play fairway is defined using a common risk segment mapping workflow. Low and high confidence play fairway extents are also calculated. In South Australia and the western most areas of Queensland, the combined gas play fairway maps show that the Nappamerri and Allunga troughs are highly prospective, along with the deepest areas of the Patchawarra and Arrabury troughs. The play fairway maps also shows prospectivity potential for unconventional gas further northeast in Queensland, including areas of the Windorah Tough and Ullenbury Depression, although reservoir thickness and maturity are the key risks for this play type outside the central depocentres and overpressure remains less well constrained due to lack of data. The prospectivity of the Cooper Basin for unconventional hybrid plays for gas far exceeds its currently known conventional resources by at least an order of magnitude. Whilst significant additional work is required to better characterise key petroleum systems elements, the play fairway area estimated for the combined Gidgealpa Group gas play is significantly larger than that of the Roseneath and Murteree shale gas plays alone, suggesting very large volumes of gas in place and highlighting the Cooper Basin's significance as a world class unconventional gas province.

The Eastern Highlands form a broad arch, with similar cross sections along its length, and varying altitude of its axis. At least on the western margin in Queensland and near Sydney, most of the uplift was by warping. Mesozoic sediments preserved on the summit and flanks of the highlands prove that most of the uplift was after the Early Cretaceous in Queensland, after the mid Triassic near Sydney, and after the Triassic in Tasmania. Uplift of the highlands was most likely initiated at the time of change of the sedimentation pattern and tectonics, 95 Ma ago, as suggested by Jones and Veevers, except that uplift is thought to have started in the Jurassic in Tasmania. Denudation rates vary with local relief. The Cainozoic average rate for Queensland and New South Wales is near 3 m.Ma-1, and for Victoria and Tasmania 5-7 m.Ma-1. Gravity studies show that the Eastern Highlands are on relatively weak lithosphere, so the denudation would have resulted in denudation isostatic rebound of the local area, and the total amount of tectonic uplift is given approximately by the smoothed altitude of the present highlands. In general, the amount of denudation is smaller than the total amount of tectonic uplift. The timing of the tectonic uplift is not well determined, but most is earlier than mid Cainozoic, and there is evidence that possibly one third of it was during the late Cainozoic. The early tectonic uplift is thought to be due to removal of the lower lithosphere from beneath the highlands at the time of rifting to form the Tasman and Coral Seas, leading to uplift both by crustal underplating, and by the short and long-term effects of crustal heating. Later tectonic uplift is thought to be caused by crustal underplating associated with Cainozoic basaltic volcanism.

Tightly folded migmatitic rocks, intruded by 1860 Ma granite and younger felsic and mafic dykes, are exposed in a band 95km long and up to 10km wide along the western part of the Kalkadoon-Leichhardt Belt. The migmatites are considered to represent the basement underlying Proterozoic cover rocks, the oldest of which are Ma felsic extrusives (Leichhardt Volcanics) about 1860 Ma old. The migmatites include thinly banded gneiss with mainly concordant leucosomes (metasediments), non-banded gneiss with wispy leucosomes (metavolcanics), and nebulitic granitic gneiss (meta-intrusives). Metamorphism and deformation of the migmatites took place before the intrusion of a cross-cutting granite dyke dated at 1860 ± 32 Ma by U-Pb zircon. Another U-Pb zircon age, 1850 ± 16 Ma, obtained for a migmatitic metadacite, is anomalously young, although within experimental error of a preferred migmatisation age of 1860 - 1870 Ma. Uplift rates of 2-5 mm a year are implied, to account for the inferred brief interval between migmatite formation and ensuing felsic volcanism.

Entropy-ratio maps enable mapping of surficial facies of coral reefs at any chosen resolution. A ternary classification uses detritus, framework encrustation, and pavement as end-members, and is subdivided on the degree of mixing of these. The classification is sensitive to all reef environments, particularly to zonation across reef flats. It can also be superimposed on other classifications. An example is given of its use in the Great Barrier Reef.

A heavy-mineral survey of the Forsayth 1:100 000 Sheet area, north-east Queensland, is described. The suitability of the technique for detecting gold, tin, and probably uranium mineralisation in the region has been established. The heavy-mineral method is also useful in the interpretation of sieved-sample surveys, and can provide valuable input to geological and metamorphic mapping programs.

The Precambrian Mount Isa Inlier in northwest Queensland is extensively cut by numerous dolerite intrusions. At least two distinct episodes of dolerite intrusion have been recognised in each of the three major tectonic units: the western succession, basement sequence, and eastern succession. Olivine and quartz tholeiites predominate. The rocks in the western succession and basement sequence display little chemical variation with time. Those of the eastern succession display greater chemical variations. The most likely present-day tectonic analogue is that of an intracontinental rift. There is no evidence in the composition of the mafic igneous rocks to suggest that they were formed in a subduction-related environment such as an island arc or continental margin.

A dryland salinity scald some 48 km2 is described from Yelarbon on the border of Queensland and New South Wales, near the headwaters of the Murray-Darling River Basin. The saline soils, including solodised solonetz, are severely eroded and readily identified on Landsat MSS imagery. A major fault (Peel Fault offset?) beneath the scald has caused saline groundwater to leak up into the soil zone preferentially at this location. The evidence for this includes regional tectonic setting, detailed site geology, a magnetic geophysical anomaly, surface drainage changes and land surface displacement, hydraulic gradient changes, and groundwater hydrochemical anomalies. Erosion of the geologically caused saline scald is being aggravated by overgrazing. An appropriate land management strategy is to fence the area and assign it nature reserve or national park status.

Recent detailed studies of key transects throughout the Clarence-Moreton Basin have shown that a revision of nomenclature is required for units in the Late Triassic to Early Jurassic Bundamba Group. Revision of the stratigraphic nomenclature and elimination of the existing confusion in names of units in the basin was considered an essential first step in understanding basin evolution and assessing petroleum potential. We redefine the Marburg Formation as the Marburg Subgroup of the Bundamba Group and divide the Subgroup into two distinct lithostratigraphic units, the uniform sandstone of the Gatton Sandstone and the mixed sandstone and mudrocks of the younger Koukandowie Formation. The formations are upgraded existing members. The Gatton Sandstone contains locally developed members along the western basin margin. The Koreelah Conglomerate Member forms the base of the Gatton Sandstone where it overlaps basement rocks, and the Calamia Member of mixed shale, mudrocks and sandstone is a basal unit in the Gatton Sandstone in more basinward sections. The Heifer Creek Sandstone Member is a prominent quartzose sandstone unit in the Koukandowie Formation along the western margin and central parts of the basin. The older mixed mudrocks and sandstone of the Ma Ma Creek Member of the Koukandowie Formation are mainly known from the northwest. This new nomenclature preserves the integrity of existing stratigraphic names and is applicable basin- wide. One new stratigraphic name, the Koreelah Conglomerate Member, is introduced.

Chemical and mineralogical data are presented for four ferromanganese samples (two nodules and two crusts) from two stations of the West German vessel Sonne. Three samples came from a dredge on the flanks of the Dampier Ridge in water 2400- 2700 m deep. One came from a core on the Lord Howe Rise in water 1549 m deep. Thick ferromanganese deposits overlie a variety of substrates including granite, gabbro and feldspathic sandstone. The ferromanganese deposits, which are up to 20 cm thick, range from round mononucleate nodules with small volcanic nuclei, to polynucleate nodules, to nodules bound together as crusts, and to laminated crusts. Both nodules and crusts are hydrogenetic in origin and have low contents of Ni, Cu and Co, and low Mn:Fe ratios of 0.48-0.91. A comparison of these results with those from three deeper water stations of Galathea and Tangaroa indicates that Mn:Fe ratios, Ni% and Cu% increase markedly in deeper water, where Mn:Fe ratios exceed 2.5, and Ni+Cu+Co values exceed 1.25%. Any future search for nodules of economic significance should be concentrated in the even deeper water areas (>5000 m) east and southeast of Gascoyne Seamount.