Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: B.A. Camac, and P.J. Boult
Date Published: September 2008
Number of Pages: 14
Abstract:
The informally named Sawpit Sandstone Member, Upper and Lower Sawpit Shale members and the Jacaranda Ridge Sandstone Member occur within lower part of the Berriasian–Valanginian Pretty Hill Formation of the Otway Basin. The Jacaranda Ridge Sandstone is a new stratigraphic member that can be mapped along a strike length of at least 90 km on the northern flank of the Penola Trough. It is interpreted as a braided fluvial, sheet-like sand, bounded at its base by a sequence boundary. The underlying Sawpit Sandstone Member varies in thickness by up to 150 m, as interpreted from well log correlations and 3D seismic data, possibly due to a combination of thinning across pre-existing structural highs and onlap onto an incised, low angle, semi-regional unconformity. The Jacaranda Ridge Sandstone is conformably overlain by the Upper Sawpit Shale Member. Within these members, six separate depositional facies, including palaeosols, are recognised from cores, wireline log signatures and Formation Micro-Scanner (FMS) images. These help define the Upper and Lower Sawpit Shale members and separate the intervening sandy section into four units of the Sawpit Sandstone Member and the overlying Jacaranda Ridge Sandstone Member.