2009
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An igneous zircon reference material (OG1) was characterised for U-Pb isotopes by ID-TIMS, and utilised to evaluate SIMS (SHRIMP) instrumental mass fractionation (IMF) of radiogenic Pb isotopes (207Pb*/206Pb*). The TIMS 207Pb*/206Pb* reference value for OG1 was 0.29907 ± 0.00011 (95% confidence limit), 3465.4 ± 0.6 Ma. The high 207Pb* (~ 30 -g g-1), negligible common Pb, and isotopic homogeneity permitted precise (± 1-2) 207Pb*/206Pb* measurements within the analytical sessions. External reproducibility of mean 207Pb*/206Pb* ratios between sessions was demonstrated for one instrument, yielding a mean IMF of +0.87 ± 0.49. The mean 207Pb*/206Pb* ratios between instruments were dispersed beyond uncertainties, with session IMF values from +3.6 ± 1.7- to -2.4 ± 1.3, and a grand mean IMF value (twenty-six sessions) of +0.70 ± 0.52, indicating a tendency towards elevated 207Pb*/206Pb*. The specific causes of variability in IMF are unclear, but generally reflect subtle differences in analytical conditions. The common practice in SIMS of assuming that IMF for Pb+ is insignificant could result in systematic age biases and underestimated uncertainties, of critical importance for precise correlation of Precambrian events. Nevertheless, a zircon RM such as OG1 can be readily incorporated into routine dating to improve 207Pb*/206Pb* accuracy and external reproducibility.
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In addition to typical VHMS deposits, the ~3240 Ma Panorama district contains contemporaneous greisen- and vein-hosted Mo-Cu-Zn-Sn mineral occurrences that are hosted by the Strelley granite complex, which drove VHMS circulation, making this district a natural laboratory to assess the role of magmatic-hydrothermal fluids in VHMS hydrothermal systems. High-temperature alteration zones in volcanic rocks below the VHMS deposits are dominated by quartz-chlorite±albite assemblages, with lesser quartz-sericite±K-feldspar assemblages, typical of VHMS systems. In contrast, the assemblages associated with granite-hosted greisens and veins, which do not extend into the overlying volcanic pile, include quartz-topaz-muscovite-fluorite and quartz-muscovite(sericite)-chlorite-ankerite. Fluid inclusion and stable isotope data suggest that the greisens formed from high temperature (~590°C), high salinity (38-56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high -18O (9.3±0.6-). These fluids are compatible with the characteristics of magmatic fluids evolved from the Strelley granite complex. Fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90-270°C), lower salinity (5.0-11.2 wt % NaCl equiv), with lower densities (0.88-1.01 g/cm3) and lower -18O (-0.8±2.6-), compatible with evolved Paleoarchean seawater. Fluids that formed quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the granite complex near the contact with the volcanic pile, had intermediate in temperature and isotopic compositions (T = 240-315°C; -18O = 4.3±1.5-) and likely indicate mixing between the two end-member fluids. Evidence of mixing between evolved seawater and magmatic-hydrothermal fluid within the granite complex, together with the lack of evidence for a magmatic component in fluids from the volcanic pile, suggest partitioning of magmatic-hydrothermal from evolved seawater hydrothermal systems in the Panorama system.
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Scientific data are being generated at an ever increasing rate. Existing volumes of data can no longer be effectively processed by humans, and efficient and timely processing by computers requires development of standardised machine readable formats and interfaces. Although there is also a growing need to share data, information and services across multiple disciplines, many standards currently being developed tend to be discipline specific. To enable cross-disciplinary research a more modular approach to standards development is required so that common components (e.g., location, units of measure, geometric shape, instrument type, etc) can be identified and standardised across all disciplines. Already international standards bodies such as ISO and OGC (Open Geospatial Consortium) are well advanced in developing technical standards that are applicable for interchange of some of these common components such as GML (Geography Markup Language), Observations and Measurements Encoding Standard, SensorML, Spatial Coordinate Systems, Metadata Standards, etc. However the path for developing the remaining discipline specific and discipline independent standards is less coordinated. There is a clear lack of infrastructure and governance not only for the development of the required standards but also for storage, maintenance and extension of these standards over time. There is also no formal mechanism to harmonise decisions made by the various scientific disciplines to avoid unwanted overlap. The National Committee for Data in Science (NCDS) was established in 2008 by the Australian Academy of Science to provide an interdisciplinary focus for scientifc data management. In 2008 an informal request from the NCDS was put to the international Committee on Data for Science and Technology (CODATA) to consider taking on a new coordination role on issues related to the development and governance of standards required for the discovery of, and access to digital scientific data.
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This map produced for the Deparment of Foreign Affairs and Trade as part of a series of maps associated with the 1997 Treaty between Australia and Indonesia. This edition updates the original map to show the Treaty boundaries between Australia and Timor-Leste. Also the Perth Treaty entry in to force. Updated 7 December 2009 from GeoCat 64946. Confidential Not for sale or general release - for internal use of DFAT only. It is for interanl use by the Department of Foreign Affairs and Trade.
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Spatial interpolation methods have been applied to many disciplines. Many factors affect the performance of the methods, but there are no consistent findings about their effects. In this study, we focus mainly on comparative studies in environmental sciences to assess the performance of spatial interpolation methods and to quantify the impacts of data properties on the performance. Two new measures are proposed to compare the performance of the methods applied to multiple variables with different units/scales. A total of 53 comparative studies were assessed and the performance of 61 methods/sub-methods compared in these studies is analysed. The impacts of sample density, data variation, and sampling design on the estimations of 32 methods are quantified using data derived from their application to 80 variables. Inverse distance weighting (IDW), ordinary kriging (OK), and ordinary co-kriging (OCK) are the most frequently used methods. Data variation is a dominant factor and has significant impacts on the performance of the methods. As the variation increases, the accuracy of all methods decreases and the magnitude of decrease is method dependent. Gradient plus inverse distance squared (GIDS), OCK and regression residual kriging (RK-C) are less sensitive to data variation. Irregular-spaced sampling design might improve the accuracy of estimation. The effect of sampling density on the performance of the methods is found not to be significant. The implications of these findings are discussed.
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This map shows the boundaries of the maritime security zones for each port for the purpose of the Maritime Transport & Office Security Act 2003. 20 sheets (Colour) May 2009 Not for sale or public distribution Contact Manager LOSAMBA project
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This paper presents a new style of bedload parting from western Torres Strait, northern Australia. Outputs from a hydrodynamic model identified an axis of bedload parting centred on the western Torres Strait islands (~142°15"E). Unlike bedload partings described elsewhere in the literature, those in Torres Strait are generated by incoherence between two adjacent tidal regimes as opposed to overtides. Bedload parting is further complicated by the influence of wind-driven currents. During the trade wind season, wind-driven currents counter the reversing tidal currents to a point where peak currents are directed west. The eastwards-directed bedload pathway is only active during the monsoon season. Satellite imagery was used to describe six bedform facies associated with the bedload parting. Bedform morphology was used to indicate sediment supply. Contrary to bedload partings elsewhere, sand ribbons are a distal facies within the western bedload transport pathway despite peak currents directed toward the west throughout the year. This indicates that sediment is preferentially trapped within sand banks near the axis of parting and not transported further west into the Gulf of Carpentaria or Arafura Sea.
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The tragic events of the Indian Ocean tsunami on 26 December 2004 highlighted shortcomings in the alert and response systems for tsunami threats to Western Australia's (WA) coastal communities. To improve community awareness and understanding of tsunami hazard and potential impact for Western Australia, the Fire and Emergency Services Authority of WA (FESA) established a collaborative partnership with GA in which science and emergency management expertise was applied to identified communities.
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The development of climate change adaptation policies must be underpinned by a sound understanding of climate change risk. As part of the Hyogo Framework for Action, governments have agreed to incorporate climate change adaptation into the risk reduction process. This paper explores the nature of climate change risk assessment in the context of human assets and the built environment. More specifically, the paper's focus is on the role of spatial data which is fundamental to the analysis. The fundamental link in all of these examples is the National Exposure Information System (NEXIS) which has been developed as a national database of Australia's built infrastructure and associated demographic information. The first illustrations of the use of NEXIS are through post-disaster impact assessments of a recent flood and bushfire. While these specific events can not be said to be the result of climate change, flood and bushfire risks will certainly increase if rainfall or drought become more prevalent, as most climate change models indicate. The second example is from Australia's National Coastal Vulnerability Assessment which is addressing the impact of sea-level rise and increased storms on coastal communities on a national scale. This study required access to or the development of several other spatial databases covering coastal landforms, digital elevation models and tidal/storm surge. Together, these examples serve to illustrate the importance of spatial data to the assessment of climate change risk and, ultimately, to making informed, cost-effective decisions to adapt to climate change.
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Case Study: GeoFrame software helps Geoscience Australia provide quick access to 2D and 3D seismic survey data within newly released license/permit in support of successful Australian Acreage Release bidding rounds