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ACRES Update, Issue 25, December 2001 Government widens access to spatial data STAR Service in agricultural industry Australian landcover as never seen before

ACRES Update, Issue 24, July 2001 STAR Service shortens delivery time ACRES Poster features impace crater A unique applicaiton using satellie imagery as art

Product no longer exists, please refer to GeoCat #30413 for the data

Product no longer exists, please refer to GeoCat #30413 for the data

Thick packages of Cretaceous and Tertiary sediment with numerous diapirs fill the Southern Fairway Basin (SFB) on the Lord Howe Rise (LHR). A bottom-simulating reflector (BSR) also extends across much of this basin, perhaps indicating substantial amounts of CH4 as gas hydrate and free gas. As part of the ZoNiCo 5 survey, run on behalf of the New Caledonian government, 13 piston cores were taken by the RV L'Atalante in 1999 to assess the gas and petroleum potential of the SFB. Specifically, the cores were recovered to document the nature of sediment, pore water and gas in the shallow sedimentary section. The 13 cores, from 1250 to 2753 m below sea level (mbsl) and between 405 and 758 cm long, contain stiff nannofossil ooze. If average regional sedimentation rates apply (10 m/my), the maximum age at the bottom of cores is less than 800,000 years. The sediment typically grades from greyish orange at the top, to very pale orange in the middle, and then to either yellowish grey, very light grey or white at the bottom. Thin black horizons, presumably composed of pyrite, also occur. The changes in colour are related to variations in magnetic susceptibility (MS) and pore water SO42-. Pale and grey zones generally have low MS punctuated by MS highs, and low pore water SO42- concentrations. Methane was detected in most sediment samples, although at trace levels. The presence of ethane, propane and higher hydrocarbons suggests that gases in the SFB have a thermogenic component. With the available data, the best explanation for colour, MS and SO42- profiles is that Fe has been remobilised under anoxic conditions. Ferric iron in solid oxyhydroxide phases and SO42- in pore waters have been converted to dissolved ferrous iron and sulphide. Some of this iron and sulphur has then re-precipitated as pyrite or magnetite (the MS spikes). The overall process may be driven by CH4 from underlying gas hydrate deposits. Upward fluxes of CH4, perhaps of thermogenic origin, induce anaerobic CH4 oxidation in shallow sediment, a process that consumes SO42-. As a consequence, unexpectedly shallow redox fronts occur in the SFB. However, longer cores with less-oxidised sediment and additional analyses are needed to understand sediment, water and gas in this region.

The report is the fourth in a series of multi-hazard case studies by the Geoscience Australia Cities Project. It is a summary report which considers tropical cyclone, including severe wind and storm tide at Gladstone. It also provides an overview of the risks posed by severe thunderstorms, floods, landslides, heatwaves, bushfires and earthquakes. Produced in conjunction with the Bureau of Meteorology and in cooperation with Queensland Department of Emergency Services, Gladstone City Council and Calliope Shire Council.

This report presents the results of a regional seafloor mapping study carried out during 2000/2001 as part of Geoscience Australia's South and Southwest Regional Project. The aim was to support future Regional Marine Planning in the Great Australian Bight (GAB) by underpinning biological, environmental and economic assessments with basic information on geomorphology and the seabed character. Four major geomorphological features are present on the margin in the South and Southwest (SSW) region: a continental shelf, marine terraces (including the Eyre and Ceduna Terraces in the GAB), a continental slope and a continental rise. The boundaries of these geomorphological features have been delineated and captured in a Geographical Information System (GIS). The GIS also includes the location of sedimentary basins, plateaus, terraces and canyons previously mapped in the region. Seabed character mapping was carried out for the GAB area only. Five echo facies have been defined in the GAB area based on the interpretation of available 3.5kHz echo-sounding records and high-resolution seismic profiles in terms of acoustic facies, and their groundtruthing against seafloor samples. The interpretation of these facies has been digitised and captured into a GIS. The GIS includes key attributes for every echo facies. The acoustic facies distribution on the GAB margin and offshore in the South Australian abyssal plain shows the importance of geological inheritance to the geomorphology and sea-bed character of the region. Facies I, which represents undisturbed, layered sediments is mainly localised on the shelf, the Eyre and Ceduna Terraces, and in the greater part of the abyssal plain. Facies II, which may represent more disturbed sediments, is confined to the Ceduna Terrace and along two elongated E-W trending areas on the abyssal plain near the continent-ocean boundary. Facies III, associated with extreme (IIIA), moderate (IIIC) and low (IIID) topography, underlies scarps, canyons, and depressions on the continental slope and the abyssal plain. The distribution of acoustic facies from the upper slope down to the abyssal plain indicates that the major sedimentary process in the deep water GAB is deposition of pelagic sediments. Reworking of sediments by both bottom currents and gravity flows is probably limited to submarine canyons.

In 1997, AGSO - Geoscience Australia (GA) and the Tectonics Special Research Centre (TSRC) at the University of Western Australian (UWA) and Curtin University conducted a joint research project to image the crustal setting of the Hamersley Province of northern Western Australia. This joint research was aimed at investigating the shallow structure of the Hamersley Province, the regions deeper basement structure and in so doing, developing an understanding of the region's tectonics and possible fluid migration pathways. The project's objectives were to obtain a better understanding of sub-surface geology of the Hamersley Province at both a regional scale and a mine scale. In particular, the project's objectives were to provide more information on: * regional crustal thickness and major features, * stratigraphic architecture of the regions mineral system, * structural architecture of the mineral system, * timing and locations of fluid migration pathways The seismic survey obtained 132 km of nominally 10 fold CMP (common midpoint) deep reflection seismic data along two transects over approximately 5 weeks of acquisition.

Legacy product - no abstract available