VIMP Report 84 - Swan Hill and parts of Balranald and Deniliquin 1:250 000 map area: A geological interpretation of the geophysical data
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Product description:AbstractThis report is the first to outline the Palaeozoic (basement) geology of the Swan Hill region and the associated map the first to give an overall interpretation of the Palaeozoic geology at 1:250 000 scale. Previous work has concentrated on the Cainozoic Murray Basin cover sequences. The oldest rocks interpreted are Cambrian ocean floor basalts of the Dja Dja Wrung Supergroup, which are present along the major faults, particularly the Governor, Log Landing and Griminal faults. These basalts are overlain in the south and west by the Cambrian St Arnaud Group and the Ordovician Castlemaine Group, and in the northeast by the Ordovician Tueloga beds. All were probably deformed in the Benambran Orogeny. A major period of granite intrusion followed. The granites may have been dextrally strained whilst still plastic, giving the Lalbert Batholith its unusual magnetic pattern. If so, it is one of the few Bindian events recorded in western Victoria. In the Devonian, a second cycle of sedimentation took place northeast of the Governor Fault system. This was followed by Tabberabberan deformation and then by intrusion of granite at about 360 Ma. The subsequent Kanimblan Orogeny seems to only have affected the southern part of the Governor Fault system, the Lake Charm and associated faults. There is little direct evidence of further sedimentation on The SWAN HILL region until the Cainozoic, but it is possible that Permian sediments from the Numurkah Trough may be present, particularly in the east. About 120 basaltic plugs were intruded, but the surficial deposits associated with these were probably eroded to provide some of the detritus for the Late Jurassic to Early Cretaceous Otway Group. Eocene to Recent Murray Basin sediments cover almost the entire area. The sediments can be conveniently divided into four sequences. The oldest is the Eocene to Oligocene Olney Formation of the Renmark Group, which is entirely fluvial and contains abundant plant material. It is topped by the Mologa Surface, which may record a time of monsoonal weather patterns. Overlying this is the Oligocene to Miocene Murray Group, which includes the fluvial Calivil Formation and the marginal marine Geera Clay. Above this are the Late Miocene to Pliocene Bookpurnong beds, Parilla Sand and Shepparton Formation time equivalents recording the offshore marginal marine and onshore facies. All lie below the Karoonda Surface. The present cycle is all fluvial (Coonambidgal Formation), lacustrine (Blanchetown Clay and unnamed lunettes) or windblown sand (Woorinen Formation, Lowan Sand). Because of the depth of cover, most exploration has concentrated on the Murray Basin. Brown coal deposits are present in Olney Formation in the Kerang-Cohuna area, but they are covered by about 100 m of overburden and contain high levels of sulphur and ash. Both sheet and strand line style heavy mineral deposits are present, with one strand line deposit, at Wemen, having been mined. Traces of uranium are known in the Lake Boga Granite and may also be present around Lake Tyrrell. Bibliographic reference Moore, D.H., 2005. Swan Hill 1:250 000 and parts of Balranald and Deniliquin 1:250 000 map areas: a geological interpretation of the geophysical data. Victorian Initiative for Minerals and Petroleum Report 84. Department of Primary Industries. Download The downloadable version of this report is supplied in PDF format: 34461 VIMP84 Report (PDF 28.4MB) Please be patient when downloading large files as this might take some time depending on your internet connection. Related products:
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