ABSTRACTS 159 alphabetically by s~rnam~ of presenting author ecology of trace-producers during the climate making them increasingly accessible to the changeover from icehouse to greenhouse in the exploration industry. The technique has also been Early Penuian. applied to assist exploration in South America and Africa, and also in planning an Orangutan Sanctuary J. Seilacher, A., 1967. Bathymetry of trace fossils. in Sumatra. Marine Geology, 5, 413-428. Understanding landscape evolution, both 2. pickerill, R.K., 1990. Nonmarine Paleodictyon within and between widely separated regions, will frol11 the Carboniferous Albert Fonnation of be significantly enhanced using GSWA's new sourhern New Brunswick. Atlantic Geology, 26, SRTM landform images. 157-163. 3. Fiirsich, F.T., Taheri, 1. and Wilms en, M., 2007. An Alternative Model for the Genesis of New occurrences of the trace fossil Paleodictyon Gold-Arsenic Deposits Hosted in Black in shallow marine environments: examples from the Traissic-Jurassic oflran. Palaios, 22, 408-416. Shale and Turbidite Successions Visualising Landscape Evolution with Ross R Large I SRTM Data: Regional Landform Mapping in the Tanami J CODES ARC Centre of Excellence in Ore Deposits, School of Earth Sciences, University of Tasmania. Richard L Langford 1 Organic-rich mudstones or shales, within thick Geological Survey of Western Australia, packages of calcareous or siliciclastic turbidites, have Depanment of Industry and Resources, 100 Plain long been recognised as important host rocks for Street, East Perth, WA 6004, Australia major gold deposits (e.g. Victorian Goldfield, Carlin (richard.langford@doir. wa.gov. au) District, Lena Gold Province, Otago Schist belt). Many of the deposits in these districts are referred to Good landfonn visualisation is an essential as orogenic gold deposits, emphasising the tectonic first step in understanding landscape evolution, and metamorphic processes involved in the particularly in a continent that is so flat. Digital concentration of gold (Groves et aI., 2003; Goldfarb topographic data from the Shuttle Radar Topography et aI., 2005). The current genetic models propose that Mission (SRTM), flown in 2000, covers 80% of the the organic-rich sedimentary host rocks are the trap­ Earth's land surface with high quality but potentially rock for gold precipitated during deformation-related undervalued elevation data, mostly at 3-second fluid flow, with the gold being transported by deep­ (-90-metre) resolution. The uniform quality of these sourced fluids of mantle or lower crustal origin, or in data means that effective landform comparisons can some cases from felsic magmas. Recent research at be made not only across large regions in W A but CODES (Wood and Large, 2007; Large et aI., 2007) also between different continents. However, this suggests the possibility that organic-rich black shales potential is only reached if visualisation techniques are potential source rocks for gold, arsenic and effectively discriminate different landforms at a vanadium, and that the gold was originally trapped on range of scales. Multi-scale surface characterisation seafloor organic material by chemical process during is a new approach to manipUlating and visualising sedimentation and concentrated in arsenian pyrite SRTM data that has revealed a complex landscape during diagenesis. Later deformation leads to gold wherever it has been applied. concentration in structural sites. LandSerf software (Jo Wood, 1996) uses a multi-scale quadratic parameterisation algorithm that Defection of K-alteration in the Cloncurry is particularly effective at extracting complex District, NW Queensland, using landform patterns in areas of low relief. Applied to Hyperspectral Mineral Maps the Tanami region this visualisation method has uncovered a hitherto unknown or poorly understood pattern of large-scale dissected pediplains, sheet­ C. Laukampl, T. Cudahy2, N.H.S Oliveri, flood fans and relicts of a much older, possibly .l.S. Cleverlel glaciated landscape. Relatively small-scale landforms, including the Wolfe Creek Meteorite I James Cook University, 'Townsville, QLD, Australia, Crater, are still well represented, further enhancing 481 ([email protected],Nick.Oliver@jcu. the use of the images in regional regolith-landform edu.au) mapping. 2 CSIRO Exploration and Mining, PO Box 1130 Effective visualisation of the landscape is Bentley, WA Australia 6151 (Thomas. Cudahy essential for understandincr creochemical and @CSIRO.llu, [email protected]) hYdrologic vectors, and theref~re ~f direct benefit in Planning and implementing regional exploration Potassic alteration in the Cloncurry District is ~rograms: Images created by the new method of spatially and genetically related to IOCG deposits in RTM vIsualisation are now a component in some the eastern Mount Isa Inlier, NW Oueensland. digital exploration packages produced by GSW A, continued next page... •~."-!l1I'jIl!----------- _____________ "_II££__ r.l.Wi!!III!!!!h!i!!l1l!'1I!I'!i1'!'l' .. ~s.;:SfA~rurJ!ll"M~F.hf!T!WjlfIJ!" puN 16Q ABSTRACTS , 0 alphabetically by surname of presenting author Hyperspectral images, released by the collaborative water saturated sedimentary regolith cover, including Queensland NGMM project between GSQ and a multiphase Eocene to Miocene palaeodrainage CSIRO, were validated as new tool for the detection system. Three gold enrichment types are identified of mineralisation related hydrothermal footprints. associated with active iron and sulphur redox fronts At the IOCG deposit of Ernest Henry within the regolith and demonstrate that gold geochemically discrete alteration shells correspond to enrichment is strongly redox-controlled. distinct mineral distributions. Regional sodic-calcic Approximately 450,000 ozs of gold were alteration was overprinted by potassic alteration with recovered from high-grade bonanza deposits, in coeval biotite- and magnetite-veining, which was in excess of 1000g/t, within quartz-rich sand, gravels turn altered by Cu-Au mineralisation and K-feldspar­ and conglomerates at the base of the palaeochannel. alteration. The various envelopes of potassic Some of this gold was detrital, preserved in oxidised alteration are interpreted as a general indicator for sediment, but most occurred in partially reduced IOCGs in the Mount Isa Inlier (Mark et aI., 2006, sediment characterised by distinctive yellow Min. Dep., v. 40, 769 - 801). goethitic staining and showed evidence of in situ A combination of specific mineral maps, chemical reworking, such as highly irregular derived from hyperspectral imaging in the VNIR to morphologies with branching protrusions, that SWIR-range, is used to detect potassic alteration in extend along microfractures and partially wrapped the Cloncurry District. "MgOH composition-" and matrix detrital grains, and high-fineness gold 2 "Fe + associated with MgOH-maps" enable us to margins, inclusion-rich extremities, micron-sized separate amphibolite facies metasediments from octahedral and hexagonal crystal growths on their hydrothermal breccias and various mafic units in the surfaces. field area, based on their distinct amphibole and An upper, sub-horizontal gold enrichment chlorite chemistry. Within some of the mafic zone at 18-25 m depth, extended laterally over a intrusives these maps exhibit a change in the strike length of 700 m at a cut-off of 0.10 ppm Au, chemistry of the MgOH-bearing silicates, independent of sedimentary horizon and coincident characterised by an increase of the Mg-content from with an upper iron redox front marked by strong core to rim. A change of the whole-rock chemistry is yellow goethitic staining. Gold in high-grade also characterised by an increasing K-feldspar­ portions, up to 20 g/t Au, was as high-fineness, fine­ content towards the rim. Although K-feldspar can not grained crystals and dendrites indicative of a be detected in the VNIR- to SWIR-range, weathering multiphase chemogenic origin. Less extensive, products of K-feldspar like muscovite and Illite are subtle gold anomalous zones also occurred at 2-8 m picked up by the "White mica abundance-" and and 12-15 m depth. "White mica composition-maps". The remotes In addition to enrichment at the iron redox sensing results are confirmed by PIMA analyses and fronts, some of the supergene resource comprised will be compared with XRD-results. low-fineness, micron-sized refractory gold grains Our study shows that hyperspectral mineral encapsulated in alunite at grades of up to 5 g/t, maps successfully identify hydrothermal alteration within strongly reduced grey clay above a secondary patterns and can be used as a powerful tool for sulphide zone characterised by supergene sulphides, exploration of IOCGs in the Mount Isa Inlier. mainly fine-grained framboidal pyrite and marcasite. Recent advances in the application of Redox-controlled Supergene Gold hydrogeophysics and regolith geoscience Enrichment within the Sunrise Dam for groundwater and salinity mapping Palaeochannel Deposit, Laverton, and management Western Australia Ken Lawrie Louisa Lawrance' Cooperative Research Centre for Landscape, I School of Earth and Geographical Sciences, The Environments and Mineral Exploration (CRC University of Western Australia, Crawley, WA, 6009 LEME), c/o Geoscience Australia, GPO Box 378, (!law rance @ ozemail.com.au ) ACT 2601, Australia ([email protected]) Sunrise Dam is a world-class gold deposit Efforts to manage Australia's water resources located on the margin of a playa, Lake Carey, near more sustainably