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  • Shallow marine sediment samples (20cm - <4m) were collected from the Petrel Sub-Basin. The samples were analysed for headspace gas and lipid content. Over the survey area, methane (C1) and the wet gases (C1-C5) were typically found to be in low abundance, with all samples containing less than 6 ppm methane and even lower levels of the wet gas components. The C1-C5 hydrocarbons were detected in trace contents (total HC gas 1.58-6.6 ppm). In comparison, the Petrel, Tern and Frigate gas accumulations are dominated by methane (mean C1 91.6 mole %) and lesser quantities of the wet gases (C2-C5 mean 3.6 mole %), with carbon dioxide being present in low abundance (mean CO2 1.8 mole %). The results of the head space gas analysis and biomarker signatures of the extractable organic matter indicate an input of recent organic matter to the marine sediments. Thermogenic hydrocarbons were not detected, implying that in Area 1, gas and oil are not leaking and accumulating in the surface sediments.

  • Geoscience Australia has created a seamless national 1-second Digital Elevation Model with consistent resolution, elevation units, and projection, incorporating the best possible source data. Data sources include the 1-second Shuttle Radar Topography Mission (SRTM) data as a baseline, and higher resolution LiDAR-derived data where available. The SRTM and LiDAR platforms produce data with very different horizontal resolutions: 1-second (approximately 30-metres) and 1-metre respectively. The vertical resolution of the datasets varies from 5-metres to 15-centimetres. In order to combine these datasets the higher resolution LiDAR is resampled to the same horizontal resolution as the SRTM dataset. The two platforms use different sensors, and detect different features. Some of the above-ground features can be automatically removed from the SRTM dataset while nearly all are removed from the LiDAR dataset. This leads to a discontinuity between the datasets that must be handled when mosaicking the two datasets together. There are several standard mosaic methods available, but none of them work suitably when combining these datasets. The elevation difference between these datasets has been overcome by using a distance-weighted mean mosaic method. This method applies a mean mosaic method that favours one dataset over the other depending on how far the seam line between the datasets is: if a point is near the edge of the LiDAR dataset, then the elevation is more similar to the SRTM dataset, and vice versa. This mosaic method has been applied to all of GA's LiDAR data holdings to create a new 1-second DEM covering all of Australia.

  • This paper will look at the next generation of medium resolution optical data delivery systems from the United States, Australia and China. It compares Earth Explorer, Web Enabled Landsat Data, the Australian Geoscience Data Cube and SatSee. This comparison reveals the various design trade-offs of each system, looking in detail at the quality, timeliness and maturity of each system. This comparison shows the many barriers to access which have been removed in the latest generation of systems and how the removal of these barriers could lead to increased or even mainstream usage of remote sensing data.

  • The dataset is made publicly available as a GIS at nominal 1:5 000 000 scale, and shows the time-space-event distribution of mafic-ultramafic magmatism in Australia from the early Archean to the present day. Development of this GIS has been a multi-year project and earlier released extracts (in viewable pdf form with accompanying Geoscience Australia Records) included compilations for the Archean magmatic record, the Proterozoic magmatic record, and the Australian Large Igneous Provinces (LIPs). Publication of the GIS completes the series with addition of the Phanerozoic magmatic record, and formalisation of the complete record of Archean-Phanerozoic magmatic events as a single series. The chronology of Australian mafic-ultramafic magmatism resolves into 74 magmatic events within, predominately, resolvable bands of ±10 million years. Each event is identified by geological units grouped by similar age - this coeval magmatism may or may not be genetically related and may be in response to different geodynamic environments. These magmatic events range in age from the Eoarchean ~3730 Ma ME 1 - Manfred Event, confined within a small remnant domain within the Yilgarn Craton, to the widespread record of Cenozoic magmatism in eastern Australia (ME 72 to ME 74). The magmatic events range in magnitude from the giant volumes of magma in Large Igneous Provinces, to events whose only known occurrence is an isolated record of dated mafic igneous rock in a single drillhole. The GIS makes it possible to focus on the location of any one of these magmatic events, or groups of magmatic events that may be of interest, and overlay context from any other information that users may have available. The delineation of magmatic events for this study is based on several hundred published ages of mafic and ultramafic igneous rocks from different isotopic systems and minerals. In addition to their ages and extents, primary recorded aspects of each magmatic event include the presence or absence of ultramafic components. Further to this, the presence or correlation of known magmatic-related mineralisation is highlighted in Time-Space-Event Charts of Australia (Appendix D, figures D1 and D2). The basis for mapping has been regional solid geology, interpreted basement geology and surface geology base maps made available by the State and Northern Territory geological surveys, providing insight into the total areal extent of the magmatic systems under cover. Also available to complement the Event GIS are the domains and element boundaries from the Australian Crustal Elements map. These boundaries which are which are based on geophysical extrapolation of crustal elements under the cover of continental basins, provide a framework of the shallow crustal structure of the continent, and are used in this guide. The Crustal Elements digital dataset is available for download from the Geoscience Australia website. Insight into the geodynamic development of the continent is provided by the magmatic event structure through time. The compilation draws attention to concentrations of mafic-ultramafic magmatism in the Archean from ~2820-2665 Ma, in the Proterozoic from ~1870-1590 Ma, and in the late Neoproterozoic-Phanerozoic from ~530-225 Ma. These three time spans contain 39 of the 74 magmatic events, 53% of the entire mafic-ultramafic magmatic event record of the continent. The periods in between have mafic-ultramafic magmatic records that are more dispersed in time. Other features of interest include the shared geographic and crustal element locations of Large Igneous Provinces and numerous events with smaller magma volumes. Read the rest of the Executive Summary in the document.

  • Gravity anomalies over granite bodies are often negative polarity and rounded polygons. These characteristics were used to trial a method to map possible locations of subsurface granite bodies. Two approaches were used to outline the geometry of rounded gravity anomalies: a) Contouring of the residual Bouguer gravity field after removal of a regional field computed by filtering of the gravity field. b) Detection of edges defined by maximum horizontal gradient of the residual Bouguer gravity field. The resulting polygons are coloured according to whether granite outcrop, or encounter in wells, falls within the gravity polygon, is near such outcrop, or not proximal to outcrop. The processing was done using software developed by the author in the Perl programming language and stored in the Energy Division software repository. The processing was organised to run in batch mode on any system on which Perl is installed, MS-Windows, Unix, Linux or NCI systems. The input and output data files are ERMapper ASCII vector format and exported to ArcGIS shape files. The visualisation tool was ER-Mapper.

  • This report outlines the high precision level survey completed between the SEAFRAME tide gauge and continuous GPS station in Apia, Western Samoa from 1 - 13 November 2011.

  • This report outlines the high precision level survey completed between the SEAFRAME (Sea Level Fine Resolution Acoustic Measuring Equipment) tide gauge and continuous GPS (Global Positioning System) station and the newly established GNSS (Global Navigation Satellite System) Station in Port Vila, Vanuatu from 16th - 21st October 2012.

  • A manual describing the procedure for using remote sensing data and open source software, QGIS, to model landslide susceptibility.

  • THis paper provides an update oo the progress towards the vision of 2007 working party of the National Committee for Earth Sciences, in association with AuScope, concept for a suite of geotransect corridors across the continent. These transects were designed to implement the recommendation of the 2003 National Strategic Plan for the Earth Sciences: 'That the nation invest in a major geotransect study to gain fundamental information about the Australian plate, from its basic structure and evolution through to its mineral and petroleum systems and surficial processes'.

  • AAM was engaged by DPIPWE to acquire LiDAR data over several coastal areas of Tasmania during March and April 2014. Granville Harbour comprises approximately 3.8 km2