Legacy product - no abstract available

Legacy product - no abstract available

Australia's Large Igneous Provinces (LIPs) span most of Earth's geological history, ranging from Early Archean to Recent. LIPs in continental Australia are represented by continental flood basalts, fragments of oceanic plateaux, layered mafic-ultramafic intrusions, sill complexes and dyke swarms. It is only in the last decade that geologists have started to focus on LIPs in Australia, mainly from the perspective of their mineral potential, particularly after the discovery of the Nebo-Babel Ni-Cu-PGE deposit in the West Musgrave Province, central Australia. The list of LIPs increased by including other well-known igneous provinces, such as the Fortescue, Warakurna, Hart-Carson, Kalkarindji (formerly known as Antrim Plateau Volcanics) and various dyke swarms (e.g., Widgiemooltha, Marnda Moorn, Gairdner). The Bunbury Basalt, although only covering a small area in the Cape Naturaliste-Cape Leeuwin peninsula, joined the list of LIPs, due to its age links with the huge Kerguelen oceanic plateau magmatism. As indicated by the world-class Nebo-Babel deposit and further discoveries in the West Musgrave and in the Kimberley region, the mineral potential of LIPs is very high. In the case of orthomagmatic mineral systems, the selection of areas or specific intrusions requires focusing on isotope systematics and trace- and major-element geochemical trends to filter out mafic-ultramafic intrusions that may not have undergone sulphur saturation from those that have experienced sulphur saturation from processes, such as crustal contamination. In eastern Australia, there are two major volcanic provinces: the Early Cretaceous Whitsunday volcanic province, which is a good example of a silicic LIP, and a 4400 km long belt characterised by recent (youngest volcano is 4600 years ago) intraplate alkaline volcanism. The mineral potential associated with these provinces is as yet not fully assessed.

Extensive benefits and tools can be gained for mineral explorers, land-users and government and university researchers using new spectral data and processing techniques. Improved methods were produced as part of a large multi-agency project focusing on the world-class Mt Isa mineral province in Australia. New approaches for ASTER calibration using high-resolution HyMap imagery through to testing for compensation for atmospheric residuals, lichen and other vegetation cover effects have been included in this study. . Specialised data processing software capable of calibrating and processing terabytes of multi-scene imagery and a new approach to delivery of products, were developed to improve non-specialist user interpretation and comparison with other datasets within a GIS. Developments in processing and detailed reporting of methodology, accuracies and applications can make spectral data a more functional and valuable tool for users of remote sensing data. A highly-calibrated approach to data processing, using PIMA ground samples to validate the HyMap, and then calibrating the ASTER data with the HyMap, allows products to have more detailed reliable accuracies and integration with other data, such as geophysical and regolith information in a GIS package, means new assessments and interpretations can be made in mapping and characterising materials at the surface. Previously undiscovered or masked surface expression of underlying materials, such as ore-deposits, can also be identified using these methods. Maps and products made for this project, covering some ~150 ASTER scenes and over 200 HyMap flight-lines, provide a ready-to-use tool that aids explorers in identifying and mapping unconsolidated regolith material and underlying bedrock and alteration mineralogy.

Legacy product - no abstract available

Large areas of prospective North and North-East Queensland have been surveyed by airborne hyperspectral sensor, HyMap, and airborne geophysics as part of the 'Smart' exploration initiative by the Geological Survey of Queensland. In particular, 25000 km2 of hyperspectral mineral and compositional map products, at 4.5 m spatial resolution, have been generated and made available via the internet. In addition, more than 130 ASTER scenes were processed and merged to produce broad scale mapping of mineral groups (Thomas et al, 2008). Province-scale, accurate maps of mineral abundances and minerals chemistries were generated for North Queensland as a result of a 2 year project starting in July 2006 which involved CSIRO Exploration and Mining, the Geological Survey of Queensland (GSQ), Geoscience Australia, James Cook University, and Curtin University. Airborne radiometric data acquired over the same North Queensland Mt Isa - Cloncurry areas as the hyperspectral surveys, had been acquired at flight line spacing of 200 metre. Such geophysical radiometric data provides a useful opportunity to compare the mineral mapping potential of both techniques, for a wide range of geological and vegetated environments. In this study, examples are described of soil mapping within the Tick Hill area, and geological / exploration mapping within the Mt Henry and Suicide Ridge prospects of North Queensland.

Micro-Raman spectroscopy has become an important, versatile, non-destructive technique that is well-suited for the study of minerals and the inclusions they may contain. This technique is particularly useful in cases where the more common techniques (e.g. electron microprobe or X-ray diffraction analysis) cannot be used, for example, because of the impossibility to separate or prepare the sample to be studied. Another advantage of micro-Raman spectroscopy is that polymorphs with the same chemical composition can be easily distinguished. Furthermore, the Raman mapping technique can be used to generate a spectroscopic map of the sample. The wealth of detailed spectral information produced during Raman mapping has made this an extremely valuable technique for detailed studies of internally heterogeneous minerals. Because of the ability to perform analyses non-destructively, the micro-Raman technique has become an extremely valuable tool in the study of gemstones, which includes their identification and the identification of inclusions, and the detection of potential treatments done to enhance their colour and clarity. For example Millsteed et al. (2005) used micro-Raman spectroscopy for the characterisation of rhodonite from Broken Hill and also the solid and fluid inclusions trapped within the rhodonite. Raman analysis has also been applied to the study of minerals that were fully or partially amorphised due to the effects of radioactivity, as for instance in radiation-damaged zircon, monazite and biotite. The Raman spectra provide information on the degree of short-range order and crystallinity, respectively. Another application based on crystillinity has been the characterisation of carbonaceous materials ranging from kerogens to granulite-facies graphite. This has led to the development of new geothermometers based on the Raman spectra of carbonaceous materials in metasediments (e.g. Beyssac et al., 2002).

Soil mapping at the local- (paddock), to continental-scale, may be improved through remote hyperspectral imaging of surface mineralogy. This opportunity is demonstrated for the semiarid Tick Hill test site (20 km2) near Mount Isa in western Queensland. The study of this test site is part of a larger Queensland government initiative involving the public delivery of 25,000 km2 of processed airborne hyperspectral mineral maps at 4.5 m pixel resolution to the mineral exploration industry. Some of the mineral maps derived from hyperspectral imagery for the Tick Hill area include the abundances and/or physicochemistries (chemical composition and crystal disorder) of dioctahedral clays (kaolin, illite-muscovite and Al smectite, both montmorillonite and beidellite), ferric/ferrous minerals (hematite/goethite, Fe2+-bearing silicates/carbonates) and hydrated silica (opal) as well as soil water (bound and unbound) and green and dry (cellulose/lignin) vegetation. Validation of these hyperspectral mineral products is based on field soil sampling and laboratory analyses (spectral reflectance, X-ray diffraction, scanning electron microscope and electron backscatter). The mineral maps show more detailed information regarding the surface composition compared with the published soil and geology (1:100,000 scale) maps and airborne radiometric imagery (collected at 200 m line spacing). This mineral information can be used to improve the published soil mapping but also has the potential to provide quantitative information suitable for soil and water catchment modeling and monitoring.

New ASTER GIS products in the Gawler-Curnamona Geoscience Australia, in collaboration with CSIRO and PIRSA are releasing a suite of 14 new ASTER mosaiced products for a significant part of the Gawler-Curnamona region. About 110 ASTER scenes have been mosaiced and processed into geoscience products that can be quickly and easily integrated with other datasets in a GIS. The products have been pre-processed and calibrated with available HyMap data and provide basic mineral group information such as Ferric Oxide abundance, AlOH group distribution as well as mosaiced and levelled false colour and regolith ratio images. These images, along with accompany notes are available for free ftp download online at: ftp://ftp.arrc.csiro.au/NGMM/Gawler-Curnamona ASTER Project/

Iron (Fe) oxide mineralogy in most Australian soils is poorly characterised, even though Fe oxides play an important role in soil function. Fe oxides reflect the conditions of pH, redox potential (Eh), moisture and temperature in the soil environment. The Fe oxide mineralogy exerts a strong control on soil colour. Visible-near infrared (vis-NIR) spectroscopy can be used to identify and measure the abundance of certain Fe oxides in soil as well as soil colour. The aims of this paper are to: (i) measure the hematite and goethite content of Australian soils from their vis-NIR spectra, (ii) compare these results to measurements of soil colour, and (iii) describe the spatial variability of hematite, goethite and soil colour, and map their distribution across Australia. The spectra of 4606 surface soil sample from across Australia were measured using a vis-NIR spectrometer with a wavelength range between 350-2500 nm. We determined the Fe oxide content from characteristic absorptions of hematite (near 880 nm) and goethite (near 920 nm) and derived a normalised iron oxide difference index (NIODI) to better discriminate between them. The NIODI was generalised across Australia with its spatial uncertainty using sequential indicator simulation. We also derived soil RGB colour from the spectra and mapped its distribution and uncertainty across the country using sequential Gaussian simulations. The simulated RGB colour values were made into a composite true colour image and were also converted to Munsell hue, value and chroma. These colour maps were compared to the map of the NIODI and both were used for interpretation of our results. The work presented here was evaluated using existing studies on the distribution of Fe oxides in Australian soils.