Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: %carbonate and specific surface area of seabed sediments.
Authors / CoAuthors
Geoscience Australia undertook a marine survey of the Vlaming Sub-basin in March and April 2012 to provide seabed and shallow geological information to support an assessment of the CO2 storage potential of this sedimentary basin. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The Vlaming Sub-basin is located offshore from Perth, Western Australia, and was previously identified by the Carbon Storage Taskforce (2009) as potentially highly suitable for CO2 storage. The principal aim of the Vlaming Sub-basin marine survey (GA survey number GA334) was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Vlaming Sub-basin that may extend up to the seabed. The survey also mapped seabed habitats and biota in the areas of interest to provide information on communities and biophysical features that may be associated with seepage. This research addresses key questions on the potential for containment of CO2 in the Early Cretaceous Gage Sandstone (the basin's proposed CO2 storage unit) and the regional integrity of the South Perth Shale (the seal unit that overlies the Gage Sandstone). This dataset comprises %carbonate and specific surface area of seabed sediments.
Australian and New Zealand Standard Research Classification (ANZSRC)
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Bottom sediments were collected using a Shipek grab. The surface sediments (~0-2 cm) within the grab were spooned into falcon vials and the porewaters were removed by centrifugation. Bulk carbonate was determined using the carbonate bomb method. Specific surface areas (SSA) were determined using a 5-point Brunauer-Emmett-Teller (BET) adsorption isotherm on a Quantachrome NOVA 2200e analyser, with nitrogen used as the adsorbate. The samples were first cleaned of organic matter by slow heating for 12 hours to 350oC. The %RSD of the SSA replicates was <1%. %RSD of the carbonate method is also ~1%.
Thanks to the crew of the RV Southern Supporter for help with sample collection.