GSV Report 116 - Charlton 1:100 000 map area geological report
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Product description:Download The downloadable version of this report is supplied in PDF format and is a large file (8.5MB). Abstract This report describes the geology of the Charlton 1:100 000 map area. It provides a summary of the previous work conducted within the map area and contains comprehensive information on the physiography, stratigraphy, intrusive history, metamorphism and structural geology. These are discussed within the framework of the regional geology of the Stawell Zone, and the geological history of the region. A list of references and numerous photographs and diagrams accompany the text. The current landscape is one of low relief foothills at the highland front, remnant coastal landforms from the formation of the Murray Basin and broad alluvial floodplains. Aeolian lunettes and longitudinal dunes have been formed on the older Cainozoic units. The oldest rocks in the Charlton 1:100 000 map area belong to the Saint Arnaud Group, a sequence of turbidites that was folded and faulted in the Silurian and intruded by granitic bodies during the early Devonian at about 400 Ma. The intrusions caused widespread contact metamorphism of the Saint Arnaud Group, which overprinted a low grade regional event associated with the Silurian deformation. Erosional processes dominated the landscape formation until the Cainozoic, when the major influences on the geology were the breakup of the Gondwana supercontinent and the formation of the Murray Basin. Most of the surface of the Charlton 1:100 000 map area is covered by Cainozoic sediments. We have placed special emphasis on the intrusive history in this report. Field mapping and geochemical data have been integrated with a new detailed geophysical interpretation, providing a unique insight into the relative ages of intrusion of the 41 recognised granitic bodies within the map area. Three major suites, the Glenloth, Coonooer and Nine Mile suites, have been defined based on the new interpretation. A combination of field mapping of the limited Palaeozoic outcrop and geophysical interpretation has been used to extend mapped structures from the south into the Charlton 1:100 000 map area. Two new faults, the Golden Jacket and O’Connors faults, have been recognised in the magnetic images. The dominant regional fabrics were generated before the oldest granites were intruded. The magnetic images also show an episode of later (post-granite intrusion) brittle faulting. Late reactivation of faults in the Cainozoic has locally influenced sedimentation in the Murray Basin. Previous exploration has focussed on gold and heavy mineral sands. A history of mining and exploration programs is presented. The known gold deposits tend to be scattered near the edges of granites in the subsurface, often close to major faults. Low rank brown coal deposits seem to be present in palaeovalleys formed by differential erosion of granites. Sites of geological interest, a summary of expired exploration licences and geochemical analyses are included in the appendices. Bibliographic reference Bibby, L.M., and Moore, D.H., 1998. Charlton 1:100 000 map area geological report. Geological Survey of Victoria Report 116. Related products:
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