Abstract for initial submission; see Geocat 71429 for conference paper version

The paper discusses the results from the GA-302 2D seismic survey and GA-2436 (RV Tangaroa) marine reconnaissance survey over the Capel and Faust basins, northern Tasman Sea. The integration of seismic, potential field and bathymetric data sets in 3D space at an early stage in the project workflow has assisted in the visualisation of the basin architecture, the interpolation of data between the seismic lines, and the iterative refinement of interpretations. The data sets confirm the presence of multiple depocentres, as previously interpreted from satellite gravity data, with a maximum sediment thickness of 5-7 km. Preliminary interpretation of the seismic data has identified two predominantly Cretaceous syn-rift and two Upper Cretaceous to Neogene sag megasequences overlying a heterogeneous pre-rift basement. The comparison of seismic facies and tectonostratigraphic history with offshore New Zealand and eastern Australian basins suggests the presence of possible Jurassic to Upper Cretaceous coaly and lacustrine source rocks in the pre- and syn-rift, and fluvio-deltaic to shallow marine reservoir rocks in the syn-rift to early post-rift successions. Preliminary 1D basin modelling suggests that the deeper depocentres of the Capel and Faust basins are within the oil and gas windows. Large potential stratigraphic and structural traps are also present.

Under the Australian Government's Energy Security Program, Geoscience Australia conducted a seismic survey and a marine reconnaissance survey to acquire new geophysical data and obtain geological samples in frontier basins along the southwest Australian continental margin. Specific areas of interest include the Mentelle Basin, northern Perth Basin, Wallaby Plateau and southern Carnarvon Basin. The regional seismic survey acquired 7300 km of industry-standard 2D reflection seismic data using an 8 km solid streamer and 12 second record length, together with gravity and magnetic data. These new geophysical datasets, together with over 7000 km of re-processed open-file seismic data, will facilitate more detailed mapping of the regional geology, determination of total sediment thickness, interpretation of the nature and thickness of crust beneath the major depocentres, modelling of the tectonic evolution, and an assessment of the petroleum prospectivity of frontier basins along the southwest margin. The scientific aim of the marine reconnaissance survey was to collect swath bathymetry, potential field data, geological samples and biophysical data. Together with the new seismic data, samples recovered from frontier basins will assist in understanding the geological setting and petroleum prospectivity of these underexplored areas.

Tholeiitic intrusion-hosted nickel sulphide deposits are highly sort exploration targets due to their potential size and co-products platinum-group elements and copper. The Norilsk-Talnakh (Russia), Voisey's Bay (Canada) and Jinchuan (China) deposits are world class examples. Although Australia holds the largest economic resources of nickel in the world, its nickel resources are mainly sourced from komatiitic-hosted and lateritic deposits. Known resources of tholeiitic intrusion-hosted nickel sulphides are relatively small, with Nebo-Babel and Nova-Bollinger in Western Australia the most significant examples. Given the abundance of tholeiitic igneous rocks in Australia, this important deposit type seems to be under-represented when compared to other continents with similar geology. To support the discovery of world class nickel sulphide deposits in Australia, Geoscience Australia has recently undertaken a continental-scale GIS-based prospectivity analysis for tholeiitic intrusion-hosted deposits across Australia. This analysis exploits a suite of new relevant digital datasets recently released by Geoscience Australia. For example, the analysis utilises the Australian Mafic-Ultramafic Magmatic Events GIS Dataset which places mafic and ultramafic rocks across Australia into 74 coeval magmatic events based on geochronological data. Whole rock geochemistry of mafic and ultramafic rocks has been used to differentiate between magma series and discriminate between different magmatic events and units within those events. Other new datasets include crustal domain boundaries derived from both deep crustal seismic data and neodymium depleted mantle model age data as well as a coverage of the minimum thickness of mafic rocks in the crust derived from the Australian Seismogenic Reference Earth Model. This continental-scale GIS-based nickel sulphide prospectivity analysis uses a mineral systems approach to map the four essential components of ore-forming mineral systems; (1) sources of ore constituents, (2) crustal and mantle lithospheric architecture, (3) energy sources or drivers of the ore-forming system, and (4) gradients in ore depositional physico-chemical parameters. These four components are combined into a prospectivity map using weights-of-evidence GIS-based techniques, with the most prospective areas across the continent occurring where all components are present. The mineral systems approach allows for the identification of a much larger footprint than the deposit itself, and can be applied to greenfield and/or undercover areas. The results highlight areas that contain known tholeiitic intrusion-hosted nickel sulphide deposits, such as the Musgrave and Pilbara Provinces, as well as regions that do not contain any known deposits, such as the southern margin of the Arunta Province in the Northern Territory, the Mount Isa Province in Queensland and the Paterson Province in Western Australia.

This presentation summarises results of 3d petroleum systems modelling of the northwestern Ceduna Sub-basin, Bight Basin, offshore southern Australia, using Schlumberger Petromod software. The model builds on two 2D models for the northern and central Ceduna Sub-basin published in Totterdell et al. (2008).

Assessing the regional prospectivity of tight, shale and deep coal gas resources in the Cooper Basin is an integral component of the Australian Government’s Geological and Bioregional Assessment Program, which aims to encourage exploration and understand the potential impacts of resource development on water and the environment. The Permo-Triassic Cooper Basin is Australia’s premier onshore conventional hydrocarbon-producing province, yet is relatively underexplored for unconventional gas resources. A chance of success mapping workflow, using rapid integration of new and existing data, was developed to evaluate the regional distribution of key gas plays within the Gidgealpa Group. For each play type, key physical properties (e.g. lithology, formation depths and extents, source rock and reservoir characteristics, and rock mechanics) were identified and criteria were used to assign prospectivity rankings. Parameter maps for individual physical properties were classified, weighted and then combined into prospectivity confidence maps that represent each play’s relative chance of success. These combined maps show a high chance of success for tight, shale and deep coal gas plays in the Nappamerri, Patchawarra and Windorah troughs, largely consistent with exploration results to-date. The outputs of this regional screening process help identify additional areas warranting investigation, and may encourage further exploration investment in the basin. This methodology can be applied to other unconventional hydrocarbon plays in frontier and proven basins.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, to October, 1954. A brief account is given of geological and geophysical operations. The results of prospecting and development work are summarised.

High Geiger readings in the vicinity of the Number 1 prospect were first obtained by Sidney Fabian (a prospector for Northern Uranium Development) who drew my attention to this fact and showed me the area on Sunday 14th November, 1954. No detailed work was done. The area was re-visited by the author on Tuesday, 23rd November, 1954. It was on this date that the region of radio-activity and the rock responsible for it were established. The Number 2 prospect was discovered independently by the author on Tuesday 23rd November, 1954, while prospecting along the line of the South Alligator Fault Zone.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, December, 1954. A brief account is given of geological and geophysical operations.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, to May, 1954. A brief account is given of geophysical operations. The results of prospecting and development work are summarised.