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Palaeoproterozoic tectonics and metallogenesis: comparative analysis of parts of the Australian and Fennoscandian Shields. Papers for a Workshop, Darwin, Australian Geological Survey Organisation.

Field investigations by AGSO-Geoscience Australia in late 2000, as part of a National Geoscience Agreement with the Northern Territory Geological Survey (NTGS), evaluated the geological setting of Proterozoic mafic-ultramafic intrusions in the Arunta Province of central Australia. The major aims of this regional study were to constrain the various mafic-ultramafic magmatic systems within the event chronology of the Arunta Province, and to provide a geoscientific framework for assessing the prospectivity and resource potential of the intrusions. This report summarises the field relationships and mineralisation features of the major mafic-ultramafic intrusions in the Arunta Province. They form large homogeneous gabbroic bodies, folded high-level mafic sills, steeply dipping amphibolite sheets and relatively undeformed ultramafic plugs with alkaline and tholeiitic affinities. Metamorphic grades range from granulite to sub-amphibolite facies. Chilled and contaminated margins and net-vein complexes resulting from the commingling of mafic and felsic magmas indicate that most intrusions crystallised in situ and were not tectonically emplaced. The intrusions were subdivided into western, central and eastern groups on the basis of lithology, metamorphic-structural history, degree of fractionation and limited geochronology. The field investigations described here and preliminary geochemical data (see Hoatson 2001) indicate that the western and central intrusions have some potential for Ni-Cu-Co sulphide deposits, whereas the eastern intrusions appear to be more prospective for platinum-group element (PGE) mineralisation. The recent emerging evidence that the eastern Arunta is prospective for PGE mineralisation is supported by exploration companies defining anomalous PGE-Cu-Au concentrations in hydrothermal veins hosted by the Riddock Amphibolite and in magnetite layers of the Attutra Metagabbro. These results, for the first time, highlight geographical differences in the mineral prospectivity of mafic-ultramafic rocks in the Arunta Province.

In 1997, AGSO - Geoscience Australia (GA) and the Tectonics Special Research Centre (TSRC) at the University of Western Australian (UWA) and Curtin University conducted a joint research project to image the crustal setting of the Hamersley Province of northern Western Australia. This joint research was aimed at investigating the shallow structure of the Hamersley Province, the regions deeper basement structure and in so doing, developing an understanding of the region's tectonics and possible fluid migration pathways. The project's objectives were to obtain a better understanding of sub-surface geology of the Hamersley Province at both a regional scale and a mine scale. In particular, the project's objectives were to provide more information on: * regional crustal thickness and major features, * stratigraphic architecture of the regions mineral system, * structural architecture of the mineral system, * timing and locations of fluid migration pathways The seismic survey obtained 132 km of nominally 10 fold CMP (common midpoint) deep reflection seismic data along two transects over approximately 5 weeks of acquisition.

The pocket in this Bulletin contains five Australia-wide correlation charts and location maps in microform (together with microform of the Bulletin text). The charts summarize the stratigraphy of the major Australian basins that belong to two categories in the Tectonic Map Map of Australia and New Guinea (1971) Trans- Australian Platform Cover and Central Australian Platform Cover. Several basins belonging to Transitional Domains have also been included because one of them (Adavale Basin) contains hydrocarbons. The platform cover in Australia that is Adelaidean to Recent in age can be studied in five major time-rock groupings, each of which forms the basis of one of the charts. These groupings are clearly similar to the 'megasequences' described by J. W. Porter and R. G. McRossan for the Phanerozoic of Canada and which appear to have worldwide significance and seem to conform to major events preceding and following the breakup of Pangaea (Basin consanguinity in petroleum resource estimation. In Haun, J. D. (Ed.), Studies in Geology No. I-Methods of estimating the volume of undiscovered oil and gas resources. Amer. Ass. petrol. Geol., Tulsa, 1975). An attempt has been made to show the lithology, maximum thickness and environment of deposition of the various beds listed. Estimates of hydrocarbon reserves are as quoted in BMR Petroleum Newsletter No. 62 (1975). A wide range of published stratigraphic correlations and interpretations has been used in the compilation. No rigid interpretation of age or equivalence of strata should necessarily be presumed by the layout of the data in the charts. Brief notes on the major time-rock groupings follow, together with selected bibliographies.

This document will be posted on the GA and CSIRO-Marine websites. Dr. Neville Exon was Chief Scientist and Cruise Leader for this survey.

The Exmouth Plateau lies oceanward of Australia's Northwest Shelf petroleum province, in water depths of 800 to 2000 m, and is flanked by the abyssal plains of the Wharton Basin. Its area is 150 000 km2 and the adjacent lower continental slopes, also considered in this study, cover another 150 000 km2 . The southwest and northwest margins of the plateau are fault-bounded escarpments, but the northern margin consists of spurs and subplateaux separated by deep troughs. Our interpretation of the area is based on 12 000 km of BMR seismic reflection, magnetic, and gravity profiles, and 6000 km of seismic reflection profiles provided by petroleum exploration companies. Initially, eight major seismic horizons were identified over the profile network. They were then related to the nearest known stratigraphy by means of seismic tie-lines to wells on the Northwest Shelf. Additional information came from magnetic and gravimetric studies and deep-sea drill holes on the adjacent abyssal plains.

This report describes the results of a micropalaeontological examination of rock samples from the lower Minilya area.

This report describes the results of a micropalaeontological examination of rock samples from the Northwest Basin, Western Australia.

The Cenozoic glacial history of East Antarctica is recorded in part by the stratigraphy of the Prydz Bay-Lambert Graben region. The glacigene strata and associated erosion surfaces record at least 10 intervals of glacial advance (with accompanying erosion and sediment compaction), and more than 17 intervals of glacial retreat (enabling open marine deposition in Prydz Bay and the Lambert Graben). The number of glacial advances and retreats is considerably less than would be expected from Milankovitch frequencies due to the incomplete stratigraphic record. Large advances of the Lambert Glacier caused progradation of the continental shelf edge. At times of extreme glacial retreat, marine conditions reached > 450 km inland from the modern ice shelf edge. This review presents a partial reconstruction of Cenozoic glacial extent within Prydz Bay and the Lambert Graben that can be compared to eustatic sea-level records from the southern Australian continental margin.