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.

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.

Abstract for initial submission, pending acceptance by convention technical program committee.

Crustal magnetism is predominantly caused by the abundantly distributed ferrimagnetic mineral magnetite which posses the property of spontaneous magnetisation. Such magnetisation is dependent on temperature, which if high enough, will cause magnetite minerals to lose their magnetic property of spontaneous magnetisation and become paramagnetic. This temperature, known as the Curie point isotherm, occurs at ~580oC for magnetite. As temperature increases with depth in the crust, the Curie point can be taken as the depth at which the crustal magnetism ceases to be recorded. Using power spectral analysis of aeromagnetic data, we have generated a Curie point depth map for the Olympic Dam region in South Australia, host to the world's largest iron oxide-copper-gold-uranium deposit. The map shows an approximately 55 km long by 35 km wide and 40 km deep hemispherical depression in the Curie point depth beneath Olympic Dam, from a background average of around 20 km. Olympic Dam is notable for its large iron and uranium content, and it is located in a region of unusually high heat flow (av. 73 mWm-2). With such high heat flow one would expect the Curie point depth to be shallow. The paradox at Olympic Dam is that the Curie point depth is deep, raising questions about the geothermal gradient, depth-integrated abundance of heat-producing elements, and the source of the iron. A possible solution to the paradox is to interpret the deep Curie point depth as a giant hydrothermal alteration zone, where the heat-producing elements have been scavenged and concentrated into the upper crust, along with the gold and copper. The iron must have a significant mantle source as it is measured throughout the full crustal column. As iron is electrically conductive, such an interpretation is supported by the high conductivity measured deep beneath Olympic Dam.

At Whites Deposit, Rum Jungle, chalcopyrite-uraninite ore has been intersected in a cross-cut at a depth of 100 ft., and sampling shows a grade of 1.5 per cent. U3O8 and 4.6 per cent. Cu. over a distance along the cross-cut of 34ft; material containing an average of 0.94 per cent. U3O8 and 2.97 per cent. Cu extends over 60 ft. Uranium mineralization is known to occur over a length of 200 ft, but the average width and grade over this distance is unknown. The ore replaces flatly pitching drag-folded beds and the width of ore along the strike is expected to vary considerably. At Dysons Prospect, about 30,000 tons of autunite-bearing ore, perhaps containing 0.25 per cent. U3O8, has been indicated by drilling. Browns Prospect is similar in many ways to Whites, but no payable ore has yet been intersected. In the district as a whole leaching of copper and uranium has been extensive and favourable areas are, in many cases, covered by soil. Structural conditions are such that non-outcropping ore is likely to be found. To-date, 3,300 ft. of drilling and approximately 700 ft. of underground prospecting have been carried out in the area and the results obtained are considered highly encouraging. Extensive drilling and underground development are warranted.

The area described in the report lies between latitudes 12°48' and 12°56' S., and longitudes 130°56' and 131°11'E. Most of the mapped region lies between the Stuart Highway and the North Australian Railway. The investigation of this area is still in the early stages and has consisted of general geological mapping, and detailed investigation (including drilling) of areas found to have been radioactive during airborne scintillometer surveys carried out in 1952. At Brodribb and Ella Creek superficial hematite-rich deposits have been found to be radioactive to the extent of up to ten times background, but drilling of this type of deposit at Brodribb has not yet proved the existence of payable primary ore. Further drilling is proceeding. A new discovery at Ella Creek in July this year gave high radioactivity over a length of about 300 ft. and two pits sunk to a depth of 3 ft. of this line have shown counts of 5,000 per minute and 10,000 per minute respectively. The field geologists recommend further testing here. In the Frazer area, laterite, which contains a belt of radioactivity up to eight times background, is known to exist, but, apart from limited trenching, has not yet been adequately tested.

Wellington is a small town on the Macquarie River about 200 miles north-west of Sydney (see Plate 1). These are several old mine workings - shafts, pits, costean, etc. - about 7 or 8 miles south-east of the town. Massive sulphide ore has been found and developed in one of these workings, namely, the main shaft of the Commonwealth Mine. A fairly big dump, which shows signs of good ore and some smelted material, is evidence that there was once a good bit of mining activity in the area. In 1951, the Consolidated Zinc Corporation became interested in the abandoned mine and arranged for the lease owner, Mr. George Wilkins, to de-water it. As pointed out in the report of the Company's geologist, nothing is known from the numerous old workings regarding the extent of the sulphide orebody. The purpose of the geophysical investigation was to determine if there is any extension to the known orebody and to provide the Company with drilling targets. The geophysical work was carried out from the end of July to the beginning of September, 1952, and it covered the whole of the old mining area, some 6,000 feet in length. The Consolidated Zinc Corporation carried out the necessary surveying work, such as pegging and levelling traverses, and the Company's drilling party assisted where necessary. The general results of the survey were discussed with representatives of the Company as soon as the field work was completed.

This address was presented at the 2009 Australian Nickel Conference held in Perth, 14-15th October 2009. Geoscience Australia has recently released two web-based map sheets (at: http://www.ga.gov.au/resources/maps/minerals/index.jsp) that show the continental extent and age relationships of Archean mafic and ultramafic rocks and associated mineral deposits throughout Australia. The maps were produced in close collaboration with the State and Northern Territory geological surveys. The Archean eon (~4000 million years to 2500 million years) represents an early part of Earth's history that is noteworthy for the earliest forms of life and the widespread occurrence of unusual olivine-rich ultramafic rocks called komatiites which contain world-class deposits of nickel sulphides. The major objective of this presentation is to promote the applications of the National map, which should be of interest to those explorers searching for nickel, platinum-group elements (PGEs), chromium, titanium, and vanadium. The new map sheets, when used in association with the `Australian Proterozoic Mafic-Ultramafic Magmatic Events' map published in 2008 (GeoCat 66114; GA Record 2008/15), summarise the temporal and spatial evolution of Precambrian mafic-ultramafic magmatism in Australia. These maps provide a national framework for investigating under-explored and potentially mineralised environments, and assessing the role of mafic-ultramafic magmatism in the development of the Australian continent.

To assist explorers, Geoscience Australia (GA) has compiled a fact sheet (2006) of products produced by GA related to those commodities (nickel, copper, cobalt, chromium, platinum-group elements, titanium, vanadium) associated with Precambrian mafic-ultramafic rocks in Australia. These products include national review publications (e.g., Nickel sulphide deposits in Australia), reports of metallogenic province studies (Kimberleys, Pilbara, Arunta, Gawler), and various maps, PowerPoint presentations, and digital datasets. Most products can be downloaded free through the www links provided on the fact sheet.

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.