Published:January 01, 2008
Widely distributed glacially derived material indicates that an extensive ice sheet covered Western Australia from at least the Gzhelian to mid-Sakmarian times. The earliest glacial sequences may be Bashkirian in the subsurface of the Southern Carnarvon and Canning Basins, although definitive glacial characteristics are less well defined. The younger glacially influenced successions are present in nearly all Phanerozoic basins in Western Australia, and typically comprise a lowermost glacial facies, middle marine mudstone facies, and uppermost fluvial–deltaic strata. Current palynological correlation show that the tripartite successions may not be coeval among all basins, which appears to contradict models of Gondwana-wide glaciation in which the end of glacial conditions is an inter-regional coeval event. However, detailed analysis is hampered by the existing low-resolution biostratigraphic scheme. There is some evidence that subsidence or penecontemporaneous faulting may have locally dominated relative sea-level change and modified regional glacial influences. A dramatic improvement in biostratigraphic resolution is required to resolve the controls on facies distribution, especially to differentiate between deglaciation patterns and periodic ice-sheet advance and retreat, and regional climatic changes and latitudinal differences within Gondwana.