Basement and crustal results from the Bremer Sub-basin, SW Australia and its Antarctic counterpart drive Australia-Russia cooperation
As part of the Australian Government's "New Oil" initiative, Geoscience Australia undertook a geophysical survey (the Southwest Frontiers Survey) of the south-western Australian continental margin in late 2004. The survey acquired 2700 km of industry-standard, 106-fold seismic data re...
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| Online Access: | https://researchdata.edu.au/basement-crustal-results-russia-cooperation/1936791 http://data.gov.au/dataset/da37ab8a-3144-4910-8721-205e2857b779 |
| Summary: | As part of the Australian Government's "New Oil" initiative, Geoscience Australia undertook a geophysical survey (the Southwest Frontiers Survey) of the south-western Australian continental margin in late 2004. The survey acquired 2700 km of industry-standard, 106-fold seismic data recorded to 12 seconds two-way time using a 6-8 km digital streamer and 4900 cui gun array. Marine reflection seismic acquisition was supplemented by recording of refraction seismic data by sonobuoys at sea and by land stations in the onshore/offshore observation scheme. Marine reflection survey shots were used as sources of seismic energy for both add-ons. The main scientific objectives of refraction work were:\n1. Provide accurate seismic velocity information to improve depth conversion of reflection seismic data and to define type of basement and crust below it underneath the sedimentary basins.\n2. Provide estimates of crustal thickness underneath major sediment deposition centres in the area to better constrain interpretation of tectonic evolution of the region.\n\nThe new refraction seismic data have substantially supplemented coverage of the area resulting from old sonobuoy work and from very few onshore stations. \n\nWhen applied to a basement travel time pick interpreted in the multi-channel reflection data set, the new velocity data indicate a maximum sediment thickness in excess of 9 km. A comparison of stacking velocities and modelled sonobuoy data suggests that, unlike in other areas, stacking velocities from the Bremer Sub-basin survey 280 can be used as a reliable substitute for acoustic velocities down to 3 s two-way time into the sediments, for the purpose of calculating sediment thickness.\n\nOne of the key findings of the refraction seismic study is that velocities in the basement are generally in the 5.2-5.6 km/s range, indicating that, contrary to priory expectations, basement in the area is mostly not granitic in composition. \n\nResults from the Bremer area conjugate counterpart in Antarctica obtained by the ... |
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