From 1 - 10 / 1023
  • Granulite-facies paragneisses enriched in boron and phosphorus are exposed over a ca. 15 x 5 km area in the Larsemann Hills, East Antarctica. The most widespread are biotite gneisses containing centimeter-sized prismatine crystals, but tourmaline metaquartzite and borosilicate gneisses are richest in B (680-20 000 ppm). Chondrite-normalized REE patterns give two groups: (1) LaN>150, Eu*/Eu < 0.4, which comprises most apatite-bearing metaquartzite and metapelite, tourmaline metaquartzite, and Fe-rich rocks (0.9-2.3 wt% P2O5), and (2) LaN<150, Eu*/Eu > 0.4, which comprises most borosilicate and sodic leucogneisses (2.5-7.4 wt% Na2O). The B- and P-bearing rocks can be interpreted to be clastic sediments altered prior to metamorphism by hydrothermal fluids that remobilized B. We suggest that these rocks were deposited in a back-arc basin located inboard of a Rayner aged (ca. 1000 Ma) continental arc that was active along the leading edge the Indo-Antarctic craton. This margin and its associated back-arc basin developed long before collision with the Australo-Antarctic craton (ca. 530 Ma) merged these rocks into Gondwana and sutured them into their present position in Antarctica. The Larsemann Hills rocks are the third occurrence of such a suite of borosilicate or phosphate bearing rocks in Antarctica and Australia: similar rocks include prismatine-bearing granulites in the Windmill Islands, Wilkes Land, and tourmaline-quartz rocks, sodic gneisses and apatitic iron formation in the Willyama Supergroup, Broken Hill, Australia. These rocks were deposited in analogous tectonic environments, albeit during different supercontinent cycles.

  • Manila Lidar Project 2011 Resupply of data from Fugro Spatial. Lidar coverage updated for seperate classification of water and bare earth. This dataset will be superseded with a new surfaces recognising water classification and hydro flatening.

  • Uraninite dating of the Kintyre deposit and Rossing South prospect using electron probe chemical U-Th-Pb technique.

  • A new continental-scale geochemical atlas and dataset for Australia were officially released into the public domain at the end of June 2011. The National Geochemical Survey of Australia (NGSA) project, which started in 2007 under the Australian Government's Onshore Energy Security Program at Geoscience Australia, aimed at filling a huge knowledge gap relating to the geochemical composition of surface and near-surface materials in Australia. Better understanding the concentration levels and spatial distributions of chemical elements in the regolith has profound implications for energy and mineral exploration, as well as for natural resource management. In this world first project, a uniform regolith medium was sampled at an ultra-low density over nearly the entire continent, and subsamples from two depths and two grain-size fractions were analysed using up to three different (total, strong and weak) chemical digestions. This procedure yielded an internally consistent and comprehensive geochemical dataset for 68 chemical elements (plus additional bulk properties). From its inception, the emphasis of the project has been on quality control and documentation of procedures and results, and this has resulted in eight reports (including an atlas containing over 500 geochemical maps) and a large geochemical dataset representing the significant deliverables of this ambitious and innovative project. The NGSA project was carried out in collaboration with the geoscience agencies from every State and the Northern Territory under National Geoscience Agreements. .../...

  • This final paper for the session presents the results of the new draft earthquake hazard assessment for Australia and compares them to the previous AS1170.4 hazard values. Draft hazard maps will be presented for several spectral periods (0.0, 0.2 and 1.0 s) at multiple return periods (500, 2500 and 10,000 years). These maps will be compared with both the current earthquake hazard used in AS1170.4 and with other assessments of earthquake hazard in Australia. In general the hazard in the draft map is higher in the western cratonic parts of Australia than it is in the eastern non-cratonic parts of Australia. Where regional source zones are included, peaks in hazard values in the map are generally comparable to those in the current AS1170.4 map. When seismicity 'hotspot zones are included, as described in the previous paper, several of them produce much higher hazard peaks than any in the AS1170.4 map. However, such hotspots do not affect as large an area as many of those in the current AS1170.4 map. Finally, hazard curves for different cities will also be presented and compared to those predicted by the method outlined in AS1170.4.

  • Advice to National Measurement Institute regarding update to the recognized-value standard of measurement for position, June 2011

  • This Record presents data collected as part of the ongoing NTGS-GA geochronological collaboration between July 2000 and June 2011 under the National Geoscience Agreement (NGA). This record presents new SHRIMP U-Pb zircon and monazite geochronological results for 18 samples from the Arunta Region, Davenport Province, Simpson Desert and Pine Creek Orogen in the Northern Territory. Five Paleoproterozoic igneous and metasedimentary samples were collected from the Eastern Arunta (ILLOGWA CREEK), and one metasedimentary sample from the eastern Casey Inlier (HALE RIVER). One igneous volcanic sample and two metasedimentary samples are from the Davenport Province (MAPSHEET) and Simpson Desert regions (HAY RIVER), respectively. Ten samples in total were collected from the Pine Creek Orogen; one igneous sample from DARWIN, the remainder being igneous and metasedimentary samples from the Nimbuwah Domain (ALLIGATOR RIVER).

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

  • Known magmatic-related uranium mineralisation is rare in Australia, despite the widespread occurrence of uranium-rich igneous rocks. Known intrusive-related mineralisation is almost entirely restricted to South Australia, while uranium mineralisation related to volcanic rocks is mostly known from northern Queensland. This apparent discrepancy suggests that Australia is under-represented in this category of uranium mineral system, and as such, the potential for future discoveries is inferred to be high. Recent work by Geoscience Australia has sought to enhance the prospectivity for a range of uranium mineral system types in Australia, including those related to magmatic rocks, by undertaking regional scale assessments of the potential for these systems. Using a similar approach, an assessment for the potential for magmatic-related uranium mineral systems has been undertaken in a systematic manner on a national scale. This has been done in a GIS environment using the fuzzy logic method, which allows for uncertainty to be captured while being relatively easy to implement. Two subcategories of magmatic-related uranium systems have been assessed: intrusive- and volcanic-related. Rather than attempting to identify specific sites of mineralisation, this investigation has focused on delineating those igneous units and events which have the highest potential for a magmatic-related uranium mineral system to operate. This allows for potentially prospective tracts to be readily identified, in which the mineral potential and uranium depositional sites may be refined using detailed local knowledge and datasets. Potentially prospective igneous rocks have been identified in all States and Territories where uranium exploration is currently permitted, including regions already known for magmatic-related uranium occurrences. Significantly, this study has identified high potential in regions which are currently not well known for magmatic-related uranium mineralisation.

  • The aim of the NPE10 exercise is the continuation of the multi - technology approach started with NPE09. For NPE10, a simulated release of radionuclides was the trigger for the scenario in which an REB-listed seismo-acoustic event with ML between 3.0 and 4.8 was the source. Assumptions made were: A single seismo-acoustic signal-generating underground detonation event with continuous leak of noble gas, radionuclide detections only from simulated release. Using atmospheric transport modelling the IDC identified 48 candidate seismo-acoustic events from data fusion of the seismo-acoustic REBs with radionuclide detections. We were able to reduce the number of candidate seismo-acoustic point sources from 48 to 2 by firstly rejecting events that did not appear consistently in the data fusion bulletins; secondly, reducing the time-window under consideration through analysis of xenon isotope ratios; and thirdly, by clustering the remaining earthquakes and aftershocks and applying forward tracking to these (clustered) candidate events, using the Hy-split and ARGOS modelling tools. The two candidate events that were not screened by RN analysis were Wyoming REB events 6797924 (23-Oct) and 6797555 (24-Oct). Event 6797555 was identified as an earthquake on the basis of depth (identification of candidate depth phases at five teleseismic stations); regional Pn/Lg and mb:Ms - all indicating an earthquake source. Event 6797924, however, was not screened and from our analysis would constitute a candidate event for an On-Site Inspection under the Treaty.