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  • A collaborative field trial of the Quester-Tangent View Series 5 single beam acoustic benthic mapping system was recently conducted in Wallis Lake by Geoscience Australia and Quester Tangent Corporation. The survey involved acquisition of the acoustic backscatter data from the northern channels and basins of Wallis Lake. Quester-Tangent software (IMPACT v3) was used to classify acoustic echograms that returned from the lake bottom into statistically different acoustic classes, using principal components analysis. Six acoustically different substrate types were identified in the Wallis Lake survey area. Ground-truthing was undertaken to identify the sedimentological and biological features of the lake floor that influenced the shape of the return echograms. For each sample, measurements were made of grain size, wet bulk density, total organic carbon, CaCO3 content, and mass of coarse fraction (mainly shell) material. Statistical cluster analysis and multi-dimensional scaling were utilised to identify any physical similarities between groups of ground-truthing sites. The analysis revealed four distinct and mappable substrate types in the study area. The degree of association between acoustic classes and measured sediment parameters was also quantified. Cluster and MDS analysis revealed that, based on the parameters measured, the six acoustic classes were not uniquely linked to the sediment groups, suggesting that factors other than the sediment parameters alone are influencing the acoustic signal. The spatial interpretation of the Wallis Lake Quester-Tangent data represents the first quantification of non-seagrass habitats in the deeper areas of the lake, and provides a useful indicatior of benthic habitat diversity and abundance. For future studies, a more quantitative measure of faunal burrow size and density, and also other sedimentary bedforms, is recommended.

  • As part of the Broken Hill Exploration Initiative (BHEI), Geoscience Australia and the Department of Primary Industries South Australia (PIRSA) recently embarked on a two-year joint project to better understand the deformational history and tectonic evolution of Palaeoproterozoic rocks in the Outalpa Inlier, South Australia. This project is one of several structural studies undertaken on these rocks although to date no consensus has emerged regarding the number, orientation and geometry of the main deformational events. To address this problem, detailed structural and stratigraphic studies were undertaken around Ameroo Hill and Tommie Wattie Bore region in the central part of the inlier where a well defined stratigraphic succession is exposed. Comparable studies undertaken in other parts of the Olary Domain indicate that the same stratigraphy and structural history are developed across the entire Curnamona Province and that the structures developed around Ameroo Hill are not atypical of the province as a whole. Included in the Olary stratigraphy is the regionally extensive and highly prospective "Bimba Formation", a marble and calc-silicate dominated unit known for its high base-metal content (Pb, Zn, Mn, Cu, Co). Geochronological studies have recently confirmed this unit as a correlative of the Ettlewood Calc-silicate in the Broken Hill Group and there is growing geochronological evidence (Page et al., 2000) that other parts of the Olary sequence can be similarly matched to equivalent units in the Broken Hill Domain. Lithostratigraphic nomenclature follows Conor (2000, 2001) who subdivided the Willyama Supergroup into two major units of contrasting magnetic susceptibility and composition: the Curnamona and Strathearn Groups. REFERENCES: Conor, C.H.H., 2000. Definition of major sedimentary and igneous units of the Olary Domain, Curnamona Province. MESA Journal, V.19: 51-56. Conor, C.H.H., 2001. Geology of the Olary Domain, Curnamona Province, South Australia: Field Guide book. PIRSA, Adelaide. Page, R.W., Stevens, B.P.J., Gibson, G.M. and Conor, C.H.H., 2000. Geochronology of Willyama Supergroup rocks between Olary and Broken Hill, and a comparison to northern Australia. In: Peljo, M. (compiler) Broken Hill Exploration Initiative Abstracts Volume, AGSO Record 2000/10: 72-75.

  • The Pine Creek 1;10,000 regolith-landform map illustrates the distribution of regolith materials and the landforms on which they occur, described using the RTMAP scheme developed by Geoscience Australia

  • The Titania Au-prospect, Northern Territory, 1:10,000 regolith-landform map illustrates the distribution of regolith materials and the landforms on which they occur, described using the RTMAP scheme developed by Geoscience Australia

  • The Oceanic Shoals survey (SOL5650, GA survey 339) was conducted on the R.V. Solander in collaboration with Geoscience Australia, the Australian Institute of Marine Science (AIMS), University of Western Australia and the Museum and Art Gallery of the Northern Territory between 12 September - 5 October, 2012. This dataset comprises an interpreted geomorphic map. Interpreted local-scale geomorphic maps were produced for each survey area in the Oceanic Shoals Commonwealth Marine Reserve (CMR) using multibeam bathymetry and backscatter grids at 2 m resolution and bathymetric derivatives (e.g. slope; 1-m contours). Six geomorphic units; bank, depression, mound, plain, scarp and terrace were identified and mapped using definitions suitable for interpretation at the local scale (nominally 1:10 000). Maps and polygons were manual digitised in ArcGIS using the spatial analyst and 3D analyst toolboxes. For further information on the geomorphic mapping methods please refer to Appendix N of the post-survey report, published as Geoscience Australia Record 2013/38: Nichol, S.L., Howard, F.J.F., Kool, J., Stowar, M., Bouchet, P., Radke, L., Siwabessy, J., Przeslawski, R., Picard, K., Alvarez de Glasby, B., Colquhoun, J., Letessier, T. & Heyward, A. 2013. Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) Biodiversity Survey: GA0339/SOL5650 Post Survey Report. Record 2013/38. Geoscience Australia: Canberra. (GEOCAT #76658).

  • The Racecourse Creek 1:10,000 regolith-landform map illustrates the distribution of regolith materials and the landforms on which they occur, described using the RTMAP scheme developed by Geoscience Australia

  • A 1:10,000 scale general reference and tourist map of the island showing settlement, mining areas, railways, roads and tracks, and the boundary of Christmas Island National Park