GSV Report 75 - Ballarat 1:250 000 geological map explanatory notes
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Product description:Abstract The Ballarat map area is located in central-west Victoria. The area in the east and south is characterised by flat plains of Late Cainozoic volcanic rocks, and partly dissected Early Palaeozoic sediments. In the northwest and west of the area a more rugged terrain is developed on Lower Palaeozoic sediment and granite. The Lower Palaeozoic sediments in the maps area were laid down in three sedimentary troughs or belts - The Grampians Trough, Stawell Sedimentary Belt and Bendigo Sedimentary Belt. The western margin of the Stawell Sedimentary Belt is marked by an assemblage of calc-alkaline volcanics. These troughs were stabilized at varying times from the Early Silurian to the Early Devonian, with sediments in the older troughs being more intensely deformed. There were two main phases of granitic intrusions during the Devonian. Glaciers laid down sediment in the northeast of the map area in the Permian. During the Late Cainozoic extensive and voluminous lava flows covered a large part of the map area, and in a number of areas buried a system of gold bearing river gravels (deep leads) of Tertiary age. The area has had a history of gold mining dating from the 1850's. There were numerous deep mines exploiting quartz reefs in Lower Palaeozoic sediment, as well as large scale alluvial mining of deeply buried river channels or 'deep leads'. Mineral exploration is current over parts of the map area with most interest being concentrated in areas of known mineralisation such as the goldfields of Stawell and Berringa, and the Palaeozoic volcanics and sediment in the Ararat-Stavely area. Extensions to the gold bearing deep lead system is also being actively searched for. Kaolin is mined at a number of localities in weathered granite. Clays are quarried from weathered Lower Palaeozoic sediment near Ballarat for brick and other clay based industries. Areas of course quartz alluvial gravels of Tertiary age are washed for the construction industry, as well as extensively used raw for roads. The map area contains a number of geological features which are of significance at a Victorian and Australian level. The buried river channels (deep leads) mined for gold last century and early this century, provide channel ways for large volumes of good quality groundwater. Download The downloadable version of this report is supplied in PDF format (28.3MB). Bibliographic reference King, R.L., 1985. Explanatory notes on the Ballarat 1:250 000 geological map. Geological Survey of Victoria Report 75. Department of Industry Technology & Resources, Victoria. Related products:
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