The global ocean absorbs 30% of anthropogenic CO2 emissions each year, which changes the seawater chemistry. The absorbed CO2 lowers the pH of seawater and thus causes ocean acidification. The pH of the global ocean has decreased by approximately 0.1 pH units since the Industrial Revolution, decreasing the concentration of carbonate ions. This has been shown to reduce the rate of biological carbonate production and to increase the solubility of carbonate minerals. As more CO2 is emitted and absorbed by the oceans, it is expected that there will be continuing reduction in carbonate production coupled with dissolution of carbonate sediments. This study was undertaken as part of a program to collect baseline data from Australia's seabed environments and to assess the likely impacts of ocean acidification on continental shelf sediments. Over 250 samples from four continental shelf areas of northern Australia (Capricorn Reef, Great Barrier Reef Lagoon, Torres Strait, Joseph Bonaparte Gulf) were analysed to characterise the surface sediment mineral and geochemical composition. Of particular importance was the quantification of carbonate minerals (calcite, aragonite, high-magnesium calcite) and the magnesium content in high-magnesium calcite. The latter determines the solubility of high-magnesium calcite, which is most soluble of all common carbonate minerals. The thermodynamic stability of carbonate minerals as referred to the state of saturation was calculated using the current and predicted equatorial ocean water composition [1]. Northern Australian continental shelf sediments are largely dominated by carbonate. High-magnesium calcite had the highest abundance of all carbonate minerals followed by aragonite in all areas. The average mol% MgCO3 in high-magnesium calcite varied from 13.6 to 15.5 mol% for the different areas, which is in agreement with the global average magnesium concentration in high-magnesium calcite in tropical and subtropical regions [2].

Preliminary zircon data and tectonic framework for the Thomson Orogen, northwestern NSW

To follow

As part of initiatives by the Australian and Queensland Governments to support energy security and mineral exploration, a deep seismic reflection and magnetotelluric survey was conducted in 2007 to establish the architecture and geodynamic framework of north Queensland. With additional support from AuScope, nearly 1400 km of seismic data were acquired along four lines, extending from near Cloncurry in the west to almost the Queensland coast.

Regional geology and prospectivity of the Aileron Province in the Alcoota 1:250 000 mapsheet area

4 maps for Ministerial. Refer to GeoCats 73029 & 73030 Not for sale or public distribution Contact Manager LOSAMBA project, PMD

This map shows the boundary of the security regulated port for the purposes of the Maritime Transport & Office Security Act 2003. 1 Sheet (Colour) May 2010 Not for sale or public distribution. Contact Manager LOSAMBA project, PMD.

This map shows the boundaries of the security regulated port for the Maritime Transport & Offshore Security Act 2003. 10 Sheets (Colour) March 2010 Not for sale or public distribution. Contact Manager LOSAMBA project, PMD.

Regional airborne electromagnetic (AEM) data provide valuable information for mapping the shallow crust. Data are particularly useful for mapping buried paleotopography including paleovalleys and paleochannels, showing the depth to conductive geological units (and perhaps related faults), and altered and weathered unconformity surfaces, that may be less evident in other regional datasets. Geoscience Australia (GA) has recently acquired and released regional AEM data in the Paterson area of Western Australia, which is one of the most highly prospective areas in Australia. GA is currently in the process of assessing the potential of basinal fluid-related uranium systems in the area, including unconformity-related, sandstone-hosted and calcrete-hosted systems. Interpretation uses this key dataset, along with other available geological, geophysical and remotely sensed data and publicly available drill hole data, Outputs of this assessment include a number of prospectivity maps for these uranium systems. Preliminary interpretations of the AEM data have identified paleovalleys containing Permian and younger sediments and fluid pathways as aquifers in Permian and younger sediments on-lapping the Rudall Complex, Fortescue Basin and Pilbara Craton. In some places, the AEM data map unconformities of Mesozoic over Permian and Permian over the Neoproterozoic Yeneena and Officer Basins and Mesoproterozoic Rudall Complex. The unconformity surface between the Neoproterozoic Yeneena and Officer Basin sediments over rocks of the Rudall Complex or Pilbara Craton appears poorly defined in the data. The AEM data are opening up new avenues of investigation for uranium systems and have shown the utility of flying regional AEM surveys over highly prospective areas.

This map shows the boundary of the security regulated port for the purpose of the Maritime Transport & Office Security Act 2003. 1 sheet (Colour) May 2010 Not for sale or public distribution Contract Manager LOSAMBA project, PMD