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  • A 2-D crustal velocity model has been derived from a 1997 364 km north-south wide-angle seismic profile that passed from Ordovician volcanic and volcaniclastic rocks (Molong Volcanic Belt of the Macquarie Arc) in the north, across the Lachlan Transverse Zone into Ordovician turbidites and Early Devonian intrusive granitoids in the south. The Lachlan Transverse Zone is a proposed west-northwest to east-southeast structural feature in the Eastern Lachlan Orogen and is considered to be a possible early lithospheric feature controlling structural evolution in eastern Australia; its true nature, however, is still contentious. The velocity model highlights significant north to south lateral variations in subsurface crustal architecture in the upper and middle crust. In particular, a higher P-wave velocity (6.24-6.32 km/s) layer identified as metamorphosed arc rocks (sensu lato) in the upper crust under the arc at 5-15 km depth is juxtaposed against Ordovician craton-derived turbidites by an inferred south-dipping fault that marks the southern boundary of the Lachlan Transverse Zone. Near-surface P-wave velocities in the Lachlan Transverse Zone are markedly less than those along other parts of the profile and some of these may be attributed to mid-Miocene volcanic centres. In the middle and lower crust there are poorly defined velocity features that we infer to be related to the Lachlan Transverse Zone. The Moho depth increases from 37 km in the north to 47 km in the south, above an underlying upper mantle with a P-wave velocity of 8.19 km/s. Comparison with velocity layers in the Proterozoic Broken Hill Block supports the inferred presence of Cambrian oceanic mafic volcanics (or an accreted mafic volcanic terrane) as substrate to this part of the Eastern Lachlan Orogen. Overall, the seismic data indicate significant differences in crustal architecture between the northern and southern parts of the profile. The crustal-scale P-wave velocity differences are attributed to the different early crustal evolution processes north and south of the Lachlan Transverse Zone.

  • ACRES Update Monitoring pastures from space Remote sensing research at Coleambally Irrigation Area Satellite imagery helps to classify Australia's estuaries

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

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

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

  • This dataset contains polygons of the extents of scanned images of all 1:250 000 scale geological maps of Australia, and information on the edition, publication date, and publisher of the most recent map edition. The dataset also contains hyperlinks to map images available as 75 DPI, 125 DPI or 250 DPI resolution JPG files.

  • This Record contains a shipboard interpretation of the data acquired on Geoscience Australia Survey 229 off the Australian Antarctic Territory from January-April 2002. The survey acquired deep-seismic and potential field data along 8600 km of profiles as part of the Australian Antarctic and Southern Profiling Project.

  • EXECUTIVE SUMMARY The estuarine process study of Wallis Lake (Webb, McKeown and Associates) identified: nutrient and animal faecal pollution; and human faecal pollution and other urban runoff pollutants from the Forster-Tuncurry area as the principal source of pollutants in the estuary. The major findings of this study are listed below. Rural and Urban Inputs The sediments at each site contained a unique miospore signature (pollen and spore) characteristic of catchment sources (although no specifically urban signature was found). The majors rivers (Sites 1 and 5) are characterised by specific biomarkers derived from terrestrial plants and by very high concentrations of dry sclerophyll (Eucalyptus Gummifera type) pollen and sclerophyll swamp (Allocasuarina/Casuarina) pollen respectively. The major river sites have strong signals related to herbivore faecal contamination, most probably from cattle. There was little input of pollen or biomarkers from the rural catchments to the shallow lagoon that constitutes the southern portion of Wallis Lake. No specifically urban signature was detected. Urban sources, such as human sewage and petroleum products were not found at Site 2 (urban catchment end-member) or any of the other sites. No specifically urban pollen was found at Site 2, although this site did have the highest concentration of exotic pollen Organic Matter in the Sediments The organic matter present at each site consists of a mixture of terrestrial and algal material; however, it is the algal material that decomposes most rapidly. Dinoflagellate indicators (microfossils and biomarkers) were present in low concentrations The occurrence of distinctive suites of miospores and biomarkers for rural catchments and the association of high concentrations of faecal (herbivore) biomarkers with rural inputs indicates that the input of organic material from these catchments can be mapped throughout the lake.

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