This was the first study of its kind, by the Commonwealth team. The study included demonstrations of the dithizone tests for traces of some heavy metals in the field environment, of operational and sampling procedures, and geochemical reconnaissance. Several reconnaissance traverses were sampled and examined. Extractable forms of copper and, in a very presumptive manner, extractable forms of lead and zinc were sought in the test materials. In addition, tests for copper, lead and zinc were made in some ignited and fused specimens. The testing procedure and results are described in this report.

Geochemical anomalies in soils over zones of lead mineralization were studied, both in known mineralized areas and in areas of suspected mineralization. The anomalies were readily detected and outlined by using a dithizone technique on acid extracts of soil samples collected from grid systems. By assuming the principles of mechanical mixing of the mineralized rock with other material during soil formation, and of downhill migration of soils, the anomalies were correlated with the zones of their origin: the asymmetric anomalies discovered are typical of such conditions. Applied to areas of suspected mineralization the geochemical prospecting was responsible for the discovery of two new bands of lead mineralization and several large lead and copper anomalies. The method proved to be extremely useful for indicating the most favourable areas for more detailed prospecting such as diamond or churn drilling and geophysical methods.

Legacy product - no abstract available

During the 1953 field season geochemical prospecting techniques were employed as an additional tool in the search for ore deposits in the Northern Territory. Areas of particular interest were those at which radio-active minerals had already been discovered or at which radiometric anomalies were being investigated. The work thus included the already proved Rum Jungle field as well as the new prospects at Brodribb, Waterhouse, Edith River, and Coronation Hill. A direct chemical test for uranium in soils was not used, the discovery of the radio-active areas being left to the sensitive ratemeters now in use. The close association between copper and uranium was used to advantage as it is present at many of the uranium prospects in the Northern Territory. It is a logical step to use the geochemical techniques to locate new copper mineralization, and then to carry investigations further by attempting to locate uranium in the vicinity of the copper, particularly in areas covered by deep soils where ratemeters are of no use. A field test for cobalt, a metal often closely associated with both copper and uranium, was developed, but of the many samples tested for this element only one gave a positive test. It is possible that the cobalt, an element which is extremely mobile in the oxidized zone, has been completely leached and dispersed from the radio-active minerals.

This record describes digital data compilation product, where several individual items are grouped for delivery on single CD-ROM. Content and number of items included in the compilation package can vary, depending on size of the individual items. The contents of this CD-ROM are as follows: Catalog # Title 25304 Northeast Pilbara GIS teaching package (byte data and real data grids) 25305 Northeast Pilbara GIS teaching package (byte-data grids)

Proterozoic Granites in Australia crop out over at least 145 000 km2 (Table 1). To assess their metallogenic potential a systematic study was undertaken of all granites as well as the composition of rocks within five kilometres of the granite boundaries (Budd et al., 2001). For the granites, data on the field characteristics (presence of alteration, miarolitic cavities, presence or absence of pegmatites etc) as well as the mineralogical, major and trace element compositions of the granites were compiled. Individual granite plutons were then aggregated into suites and Supersuites on a province basis. Data were also assembled on the mineralogical composition of the host rocks, specifically the presence of reactive minerals such as carbonate, carbon, feldspar, magnetite and hematite. A GIS was constructed of all data, and simply proximity analysis was used to intersect the granite plutons as well as 5 km buffers around each pluton with known mineral deposits and occurrences. The commodities and ore deposit types were recorded around each pluton. Each occurrence was checked to ensure its age was ? the age of the related intrusion. On the basis of similarities between Suites/Supersuites of different provinces nine granite associations were identified based on their chemical characteristics, pressure/temperature conditions in their source region and their associated metallogeny. Due to insufficient data, 8.3% of exposed Australian Proterozoic granites could not be classified (Table 1). The differences between each Association and its metallogeny is believed to be controlled by first order differences in temperature and pressure conditions in their source regions. Second order changes that also influenced metallogeny, are imposed by interaction with their host rocks.

Chemical modeling of gold mineralisation in the Lachlan Fold Belt shows that gold can be precipitated over a wide temperature range (from 320 to 200 ?C in this study) from CO2-bearing, low salinity, aqueous fluid flowing upwards through faults in turbiditic sequences. In agreement with field observations, the veins are predicted to be mostly quartz (> 93 vol.%) with minor amounts of pyrite, arsenopyrite and muscovite (sericite) precipitating above 230 ?C. The predicted alteration assemblage contains pyrite, arsenopyrite, calcite, muscovite (sericite), chlorite and feldspar. Varying some of the chemical characteristics of the initial fluid has resulted in the following changes to the model: Preventing the fluid from boiling stops gold precipitating below 310 ?C but has little effect on the vein mineralogy or the mineralogy of the surrounding alteration assemblage. Removing CO2 from the fluid also prevents gold precipitation in the veins below 300 ?C. The modeling also generates an alteration assemblage with a number of Ca-rich minerals as less calcium carbonate exists in this system. Removing sulfur species from the initial fluid decreases the amount of gold precipitated by more than a factor of ten, which is to be expected if sulfur ligands are the main species for gold transport. However, the vein assemblage and the lack of sulfide minerals in the surrounding alteration assemblage also suggest that sulfur species are important in this mineral system. Increasing the initial oxidation state (?O2) of the fluid inhibits gold precipitation in the veins above 260 ?C and leads to a high proportion of dolomite in the surrounding alteration assemblage. On the other hand, decreasing the initial oxidation state of the fluid lead to gold precipitation over a range of temperatures below 310 ?C but predicts that mainly graphite ? quartz precipitates in the veins and that the surrounding alteration assemblage is dominated by feldspar proximal to the veins. This style of mineralogy is not commonly observed in gold deposits in the Lachlan Fold Belt. Increasing the initial pH of the fluid inhibits the amount of minerals that precipitate in the veins, which are dominated by calcite at high temperatures and graphite at low temperatures and corresponding minor amounts of gold. The proximal alteration assemblage is dominated by K-feldspar with amphibole, biotite and epidote. This mineral assemblage is not commonly observed in these deposits. Decreasing the initial pH of the fluid allows gold to precipitate below 280 ?C but generates a proximal alteration assemblage dominated by pyrophyllite, which again is not commonly observed. The results are in agreement with the widely accepted premise that gold is transported as bisulfide complexes and that the ore-bearing fluid is typically a low-salinity, mixed aqueous-carbonic fluid with low-moderate CO2 contents (Ridley and Diamond, 2000). However, the modeling has shown that the absence of certain physico-chemical processes or fluid constituents, such as boiling or lack of CO2 may inhibit gold precipitation in some environments. Large fluctuations in ?O2 or pH will also significantly change the vein and alteration mineralogy and generally reduce the amount of gold that is precipitated. This suggests that these fluids remain rock buffered during their journey from the source to the trap site.

The North Australia Project (NAP) was initiated in July 2000 following negotiations between the Northern Territory Geological Survey (NTGS) and the Australian Geological Survey Organisation (now Geoscience Australia). The NAP was a joint project undertaking geoscientific studies in the Tanami, Arunta and Tennant regions of central Australia to help encourage mineral exploration. The project continued until June 2004, when the Geological Survey of Western Australia (GSWA) began regional data acquisition in the western Tanami region. In July 2004, the Tanami Project, a joint initiative between Geoscience Australia, NTGS, and GSWA to increase mineral exploration replaced the NAP. Although NTGS and GSWA have continued interests in the Tanami and Arunta regions, the collaborative Tanami Project will finish in December 2006. The purpose of this product is to provide reports and datasets summarising the results of the project at this time. The only major products not included in this DVD are the results of the Tanami seismic survey and modifications to the on-line 3D models required by the seismic results. These will be released separately, beginning in August 2006. As this report is intended to be as up-to-date as possible, it refers to a number of manuscripts that are either in press or in preparation. Although these manuscripts cannot be provided here, much of the data upon which the conclusions are based are presented in summary, either in abstracts, presentations, or data tables.

This data package is an archive of geospatially located and other digital geological and geophysical data covering the Tennant Inlier in the Northern Territory, a portion of the North Australia Project undertaken to understand elements within the North Australia Craton and its boundaries. It includes digital geospatial data and/or images for a number of regional scale, 1:250 000 scale and 1:100 000 scale geological map sheets, mineral locations, geophysical images, company drill hole and rock chip locations, company and Geoscience Australia geochemistry, and other regional themes. It also includes geophysical gravity data acquired by the project in the Tennant Inlier, including an ERMapper data set.

Models for the crustal evolution of the Yilgarn Craton have changed in the last 25 years from generally autochthonous greenstone development on sialic crust (Gee et al. 1981, Groves & Batt 1984) to alloch-thonous models that highlight the importance of accretionary tectonics (Myers 1995). Recent models highlight the importance of mantle plumes and long-lived convergent margins for both Au and Ni (Barley et al. 1998). The role of sialic crust in the development of the abundant mineral systems in the Yilgarn, and Archaean cratons in general, however, remains problematic. Felsic rocks from across the Yilgarn Craton are used as crustal probes, with their geochronology, zircon inheritance and Nd isotopic character used to constrain the age and extent of basement terranes. The studies reveal a collage of crustal fragments and implicate both autochthonous and allochthonous crustal development, with increasing importance of accretionary tectonics, particularly after 2.8 Ga. The crustal evolution places significant constraints on the development of metallogenic associations.