2014
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Update on Australia's oil and gas activities with a focus on recent exploration successes and promotion of open offshore acreage
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The Frome airborne electromagnetic (AEM) survey delivers fit-for-purpose pre-competitive AEM data to aid the search for energy and mineral resources around the Lake Frome region of South Australia. The Survey includes a total of 32,317 line kilometres of high quality airborne geophysical data over an area of 95,450 km2, or 10% of South Australia, at a flight line spacing mostly of 2.5 km, expanding to 5 km spaced lines in the Marree-Strzelecki Desert area to the north. The Lake Frome region contains a large number of sandstone-hosted uranium deposits associated with Paleogene and Neogene palaeodrainage systems flowing from uranium-enriched Proterozoic rocks of the Curnamona Province. Known resources are ~60,000 tonnes of U3O8 including the In Situ Recovery (ISR) operations at Beverley, Pepegoona, Pannikin and Honeymoon, and deposits at Four Mile East, Four Mile West, Yagdlin, Goulds Dam, Oban and Junction Dam. The region continues to be a focus for the South Australian uranium exploration industry, particularly in the southern Lake Frome area and around the flanks of the northern Flinders Ranges. An integrated interpretation approach including a review of sandstone-hosted uranium mineral systems models in the Lake Frome region improved the understanding of mineral systems in this area. This informed the mapping of critical features of sandstone-hosted uranium mineral systems including basin architecture, palaeovalley morphology, sedimentary facies changes, hydrological connections between uranium sources and uranium sinks, and geological structures. A synthesis of pre-existing groundwater flow systems data, isotopic dates of uranium deposits, thermochronology data and zircon provenance data further constrain a landscape evolution model for the Mount Painter and Mount Babbage inliers in the northern Flinders Ranges, affecting the mineral systems models. The AEM data and subsequent interpretation comprehensively remap palaeovalley systems in the southern Lake Frome area and point to the potential for new uranium discoveries in New South Wales adjoining the survey area to the east. The data provide a new understanding of the interaction between range-bounding fault systems and the Mesozoic and Cenozoic stratigraphy around the northern Flinders Ranges and new insights for sandstone-hosted uranium systems models for this area. New palaeodrainage systems to the north of the Flinders Ranges, associated with sandstone-hosted uranium discoveries, have also been interpreted from the AEM data The Frome AEM Survey dataset maps critical features of sandstone-hosted uranium mineral systems, geological surfaces and depth of cover to ~300 m. By providing a regional framework for mineral explorers, the results reduce exploration risk by showing where AEM is effective and what it responds to, and also allows mineral explorers to merge their own tenement scale exploration results and high resolution ground EM or AEM surveys and place them in a regional context.
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The North Australian Element (NAE) is one of the most richly endowed cratonic blocks in the world, containing major Zn-Pb, U, Cu-Au, diamond and Au deposits as well as smaller deposits with a range of other commodities. This richness results from a complex tectonic history extending from the Archean through to the Paleozoic. The NAE largely assembled before ~1840 Ma through accretion of the Kimberley and Pine Creek provinces from the northwest, the Numil-Kowanyama Province from the east and Aileron Province from the south onto a proto-NAE comprising the Tanami-Tennant and Isa provinces. The last major growth of the NAE occurred during accretion of the Warumpi Province from the south at ~1640 Ma. This overlapped development of the North Australian Basin System along the eastern flank between ~1800 Ma and 1540 Ma. Since then the NAE has been affected by 1540-1500 Ma A-type magmatism, Meso- to Neoproterzoic alkaline magmatic events, and the development of the intracratonic Neoproterozoic-Paleozoic Centralian superbasin, which was terminated by Paleozoic inversion associated with accretion in the Tasman Element to the east. The oldest significant mineral deposits - VHMS, orthomagmatic Ni-Cu-PGE and REE deposits - relate to convergence and docking of the Kimberley and Pine Creek provinces at 1865-1830 Ma. The ~1850-1845 Ma Tennant Creek IOCG event may relate to convergence of the Aileron Province. Small VHMS (1810-1765 Ma) deposits and, possibly, the Tanami and Pine Creek lode gold provinces (1810-1795 Ma) relate to north-dipping subduction along the southern margin of the NAE. Syn- to post-collisional magmatism associated with the Strangways event, which terminated subduction, produced widespread but relatively minor W-Mo and Sn deposits at 1740-1720 Ma. Development of the North Australian Basin System was accompanied by U (1740-1610 Ma) and Zn-Pb (1690-1575 Ma) events, many of which correspond in time to bends in the apparent polar wander path. The last Mesoproterozoic mineralising events in the NAE occurred at 1540-1500 Ma, involving IOCG, sediment-hosted Cu, and apatite-REE-U-Th vein deposits. Between ~1500 Ma and initiation of the Centralian Basin System at ~850 Ma, mineralisation was associated with alkaline magmatism, including one of the world's the world's largest diamondiferous diatreme at ~1180 Ma. The most recent period of mineralisation accompanied inversion of the Centralian superbasin and included ~360 Ma MVT and ~320 Ma lode gold deposits.
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Seismic and fisheries data analysis In recent years, Australia's commercial fishing industry has raised concerns over potential impacts of standard industry seismic acquisition techniques on commercial fishing business. Fishing industry claims range from short-term injury and death of individual organisms to long-term decreases in stocks for a range of commercial species. The limited scientific research available restricts government and regulators ability to make evidenced based decisions on management of these competing resources. Significant time and funding are necessary to address all aspects of this complicated issue. However, it is unclear who will take responsibility for addressing the problem. Current research is limited by poor understanding of spawning patterns, habitats and environmental factors affecting stocks of most commercial species, as well as quality and attributes recorded in long-term fishing data. Geoscience Australia and CSIRO have undertaken an empirical statistical analysis of available data for the Bass Strait area of Victoria, to assess whether evidence exists for long-term evidence for impacts. Bass Strait represents a useful test case with co-located fishing and oil and gas industry activity occurring over >60 years. Major inputs to the study include Federal and State Government managed long-term fishing catch/effort datasets for key commercial species, and Geoscience Australia archived industry seismic data for 1960s to the present for the Gippsland and Bass Basins.
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Promotional flyer for conferences describing Geoscience Australia's seabed mapping capabilities and work programs.
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The high spatial resolution achievable with SHRIMP (typically ~20-40 µm) has revolutionised U-Pb zircon geochronology, although at the cost of relatively lower precision. Whereas SHRIMP Pb isotopic ages are calculated directly from the measured ratios, SHRIMP 206Pb/238U ages are not and depend on a calibration involving concurrent analyses of a natural zircon standard which introduces an additional source of uncertainty besides ion counting statistics. Understanding the components of analytical uncertainty associated with SHRIMP 206Pb/238U ages as well as the limitations of the instrument used, is important for the deployment of SHRIMP resources to solving geological problems.
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Reproduction of GA Insights article in PESA News. http://www.ga.gov.au/about-us/news-media/news-2014/new-geophysical-data-for-co2-storage-and-hydrocarbon-prospectivity-in-the-browse-basin.html
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Preface to Special Issue of Mineralium Deposita on critical commodities
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The secular distribution of zinc deposits is episodic and related to the supercontinent cycle and hydrosphere oxygenation. Peaks in deposits hosted by volcanic-dominant successions (aka VMS deposits) are associated with supercontinent or supercraton assembly, particularly Kenorland (2740-2680 Ma), Nuna (1900-1760 Ma), and Pangea (550-300 Ma), although no peaks are associated with Rodinia assembly. Outside these periods, formation and/or preservation of these deposits was poor. These deposits form along introverted convergent margins, and this distribution probably results from high heat flow, rapid obduction and a greater likelihood of preservation. The distribution of stratiform deposits hosted by clastic-dominated sequences (aka "SEDEX" deposits) differs from that of volcanic-dominated deposits. Although both are characterized by peaks during Pangea assembly, their Precambrian distributions differ. There are no examples of clastic-dominated deposits before 2100 Ma, and Proterozoic clastic-dominated deposits are associated with breakup, not assembly, of Nuna and Rodinia. Low temperature deposits hosted by carbonate-dominated successions (aka MVT deposits) are mostly associated with Pangea assembly. Precambrian examples are uncommon; none are known before 2100 Ma. Preserved higher temperature, carbonate-hosted deposits that are coeval with magmatism (skarn and related deposits) are mostly geologically young, generally Tertiary in age, although older deposits (to ~1820 Ma) are known. This distribution may be related to preservation as these deposits commonly occur in arcs that are eroded during later orogenesis. Most zinc deposits are temporally associated with the assembly of supercontinents, except Rodinia. Zinc deposits not associated with supercontinent assembly are hosted by clastic-dominated successions, which can occur in extensional environments associated with supercontinent stability and break-up. The association with supercontinent assembly is probably related to the presence of magmatic (mostly back-arc, but arc for skarn deposits) and orogenic environments critical to formation/preservation along convergent margins. The lack of deposits associated with Rodinia assembly may relate to the dominance of advancing accretionary orogenesis and extroversion during Rodinia assembly. The lack of clastic-dominated and low temperature carbonate hosted deposits prior to the early Paleoproterozoic may relate to the reduced nature of the hydrosphere prior to the Great Oxidation Event at ~2400 Ma.
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This report provides Department of Environment with a summary of the work that we carried out for them to run and maintain he Darwin IFCI antenna during the year 2013/2014.