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Geoscience Australia is the national mapping agency, providing fundamental geoscientific data in support of mineral and petroleum exploration.

Australia hosts a large number of world-class deposits that underpin its position as one of the world's most important suppliers of minerals, ranking in the top 6 producers of bauxite, coal, copper, diamonds, gold, iron ore, lead, manganese, mineral sands, nickel, silver, tantalum, and zinc. To assess Australia's potential for further world-class deposits AGSO has developed a national scale GIS using a mineral systems approach based on identification of the critical elements of selected ore deposit types relevant to Australian terranes and time-event plots of key events within particular terranes. Other important components in the GIS are AGSO's continental scale geological, geophysical and mineral deposit/occurrence databases. The GIS includes layers of mineral potential, regional-scale assessment criteria, grade and tonnage curves for deposit styles, and an estimate of the certainty of assessment. Initially the GIS and outputs are at the 1:5 million geo-province scale but will followed by more detailed assessment at 1:1 million and 1:250 000 scale. Density maps of Au, Ag, Cu, Ni, Sn, Pb and Zn and U mineral occurrences define provinces with anomalously high metal contents and outline the major mineral provinces. Most of the regions (but with notable exceptions) with anomalously high distribution of mineral occurrences contain one or more world-class deposits of that metal(s). A comparison of the density plots with the distribution of favourable host rocks based on trap and/or source characteristics for the particular metal(s) from the GIS delineates areas that have a potential to host similar deposits. These plots highlight that much of Australia's undiscovered potential lies under regolith or shallow sedimentary cover. Large areas under shallow cover (< 500m) with mineral potential can be delineated using the mineral occurrence density plots and either the continent and regional scale potential field data, or the Australian Crustal Elements Map that divides Australia into distinct geophysical domains based on the magnetic and gravity characteristics of the basement.

Hydrothermal zircons have been previously reported from F- and/or CO2-rich systems (Rubin et al., 1993), quartz-tourmaline mesothermal gold veins (Claoue-Long et al., 1990; Kerrich and King, 1993), and at the Olympic Dam Cu-uranium deposit (Oreskes and Einaudi, 1990). Zircon mobility has also been inferred from the volatile-induced transport of immobile-element-enriched, magmatic-hydrothermal fluids at shallow levels in high-K calc-alkaline volcanic systems in acid-sulphate hydrothermal alteration of rhyolitic volcanics. However, it has previously been difficult to prove that the zircons were truly hydrothermal in origin. This paper outlines the methods we have used to characterise and chemically fingerprint hydrothermal zircons from porphyry Cu-Au, epithermal and lode gold deposits. Hydrothermal zircons were characterised by the following multi-techniques: (1) their distinct morphology and their paragenetic relationships to the ore and mineral assemblages within the veins, (2) the higher concentration of zircon within the quartz veins relative to that of the host rocks, (3) the abundance of solid (e.g. pyrite, rutile, arsenopyrite, alunite) and/or fluid inclusions within the zircons, and (4) their trace element zonation as measured by the CSIRO-GEMOC nuclear microprobe. The following table give some examples of elemental enrichment/zonation in hydrothermal zircons examined in our studies: DEPOSIT TYPE ELEMENTAL ZONATION Enterprise Lode Gold Deposit Cu, As, Ag, Sn, Sb, Ba Bottle Creek Lode Gold Deposit Fe, As, Sr, Sn ,Sb, Ba Gidginbung Epithermal Deposit As, Sb, Th, Yb, U, Y, Hf Nena Epithermal Deposit Fe, Cu, Yb, Th, Sn, Sb, Ba The Dam Porphyry Deposit Fe, Cu, Sn ,Sb, Ba Many mineral deposits cannot be precisely dated due to the lack of suitable zircon-bearing host rocks or due to the resetting of other isotopic systems. Mineral deposits are particularly vulnerable to subsequent modification due to their formation in near surface and/or dynamic tectono-magmatic environments. In these instances, U-Pb dating of hydrothermal zircons directly associated with mineralisation may have a particular advantage over other isotopic systems that rely on less stable minerals.

In December, 1950, the Pakistan Government filed a formal application to Australia, through the Technical Assistance to South-East Asia Co-operation Scheme, for three geologists to carry out geophysical surveys in Pakistan. In May 1951, the geologists, J.F. Ivanac and D.M. Traves of the Bureau of Mineral Resources and D. King of the South Australian Mines Department, arrived in Pakistan. Their instructions were to carry out a geological survey of a portion of the Gilgit Agency, and to discuss with the Director of the Pakistan Geological Survey or any other Government Officer familiar with the problem, the alluvial gold deposits of Chitral River and the lignite deposits of West Bengal and Sind. Field investigations commenced from Gilgit in June 1951, and the party spent four months in the region. This report gives an account of the visit and the results of the investigation.

An airborne gravity gradiometer (AGG) survey has been flown over the Broken Hill region. The survey involved the NSW Department of Mineral Resources in collaboration with the CRC for Predictive Mineral Discovery (pmd*CRC) as principal research project sponsor. Interpretation of these data is expected to assist explorers to locate discrete targets that have anomalous density. This is relevant to exploration for base metal, Fe-Cu-Au and Ni-Cu-Pt-Pl deposits in the region. The data will also provide a significant new data layer for geological mapping and mineral system research, and will provide further insight for exploration across the entire Curnamona Province.

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

The National Geochemical Survey of Australia (NGSA) project was launched in 2007 as part of the Australian Government's Energy Security Initiative. Knowledge of the concentrations and distributions of chemical elements in the near-surface environment, used in combination with other datasets, can contribute to making exploration for energy and mineral resources more cost-effective and less risky. As a spin-off, the multi-element dataset can also have applications in environmental fields. During precursor pilot projects, various sampling media, grain-size fractions and analytical methods were tested. It emerged that catchment outlet sediments (from either overbank or floodplain landforms, or from similar low-lying settings) were an ideal sampling medium found across Australia. These sediments are well-mixed composites of the dominant rock and soil types of a catchment, and are typically fine-grained. Results from the pilot projects indicated that catchment outlet sediments could reflect geochemical signatures from basement and mineralisation, even through thick transported overburden. Building on these methods, the NGSA project targeted catchment outlet sediments as a uniform sampling medium. A shallow (0-10 cm) and a deeper (~60-80 cm) sediment sample was collected at the outlet of 1186 catchments covering ~80% of the country. Sampling was carried out by State and Northern Territory geoscience agencies following protocols described in the Field Manual and practiced during in-field training with Geoscience Australia project staff. All sampling equipment (augers, shovels, etc.) and consumables (bags, labels, etc.) were provided centrally. Dry and moist Munsell colours, soil pH, digital photographs, site information and GPS coordinates were recorded in the field. .../...

The National Geochemical Survey of Australia (NGSA) was initiated in late 2006 and details of progress were published in Caritat et al. (2009). The ultra-low density geochemical survey was based on overbank sediment sampling at strategic locations in the landscape. Included in the analysis methods was a partial extraction by the Mobile Metal Ion (MMI) technique (Mann, 2010) of sediment sampled at the depth of 0-10 cm, air-dried and sieved to <2 mm. The MMI method is based on solubilisation of ions loosely adsorbed onto the surfaces of minerals and, where present, organic matter. Thus, MMI results can be indicative of elements that have moved relatively recently through the regolith, and these can reflect unusual element concentrations at depth, whether caused by lithology or mineralisation. Broad lithological types (sedimentary, igneous, etc.) appear to be reflected by the geochemical patterns of several elements as determined by MMI analysis. For example, sedimentary provinces such as the Great Australian Basin and the Murray-Darling Basin are commonly associated with elevated MMI Ba, Ga or Sr values. Felsic igneous intrusive rocks along much of the eastern seaboard of Australia and in south-western WA, are typically coincident with high MMI concentrations of La, Ce and other rare earth elements. Medium to high grade metamorphic rocks do not appear to be characterised by anomalously high concentrations of any element as analysed by MMI, but can be characterised by moderately elevated concentrations of Cs, K, Mo, Rb and W in the MMI data. The applicability of ultra low-density MMI data to exploration for commodities including Au, Cu, Pb, Zn, Ni and U has also been investigated. For example, the MMI Au concentrations .../...

,,,/,,, Censored data (<Lower Limit of Detection) was imputed using a neural networks-based analysis. The compositional data was transformed using centred logratios (clr) to circumvent closure issues. A Principal Component Analysis (PCA) was then performed on the dataset. The four first PCs account for 59 % of the variance in the dataset. Both negative and positive loadings of each of these PCs relate to geological processes consistent with the element associations they represent as well as the spatial distribution patterns they produce. For instance, the positive loadings of PC1 represent the accumulation of resistant minerals rich in Rare Earth Elements (REEs) that results from intense weathering. Negative PC1 loadings represent secondary minerals formed during weathering (carbonates, sulfates, Fe-oxihydroxides). Negative PC2 loadings are a mixture of elements (e.g., Co, Mn, Zn, V) characterising mafic and ultramafic minerals; conversely negative PC3 loadings (e.g., K, Rb, Na, Sr, Ca) represent more felsic minerals. Spatial distributions of the PCs are compared with independent spatial dataset such as geological maps, airborne radiometric and spaceborne spectroscopic datasets and the implied processes (e.g., lithological control, weathering, transport, secondary mineral precipitation) overall match well with this new geochemical evidence. Future work directions with this dataset include lithological prediction and mineral prospectivity analysis.