Publication Name: The Sedimentary Basins of WA
Authors: Ian A. Dyson
Publication Volume: 2
Date Published: December 1998
Number of Pages: 22
Reference Type: Book Section
Abstract:
The M. australis Sandstone is a glauconite-rich reservoir within the Lower Cretaceous greensand succession of the Carnarvon Basin. There have been problems with stratigraphic nomenclature for the greensand succession and these may be resolved by a reconciliation of palynology with the sequence stratigraphic and lithostratigraphic schemes. Three depositional sequences are contained within the M. australis palynozone and these are designated from lower to upper as Australis 'A', 'B' and 'C' sequences. The sequences are arranged as a retrogradational set within the Barrow and Dampier sub-basins where the M. australis Sandstone comprises greensands that were deposited in estuarine, shelf and shoreface environments. At Wandoo in the Dampier Sub-basin, incised valley fills of the M. australis Sandstone are represented by three T-R cycles that are arranged in a progradational set. In these settings, the greensands may overlie sequence boundaries, but also wave and tidal ravinement surfaces and as such are often diachronous. Therefore, exploration for greensands should be carried out using a fully integrated approach within a sequence stratigraphic framework.