Executive summary:
As part of the Victorian Gas Program (VGP), the Geological Survey of Victoria (GSV) is studying the Otway Basin's petroleum systems components (reservoir, seal and source), to assess its petroleum prospectivity and to estimate the potential for further conventional gas discoveries onshore and offshore within Victoria's jurisdiction.
Reference to geological structural elements (e.g. the Penola Trough or Port Campbell Embayment) enable geologists to convey ideas about geological features in specific locations. Throughout the VGP, geological structural elements such as troughs or depocentres, platforms, basement and topographic highs have been referenced. As the studies progressed, it was evident that a standard set of names and boundaries for structural elements in the Victorian Otway Basin needed to be defined.
New data and interpretations arising from VGP studies, such as the airborne gravity data (Carter et al., 2019) and the 3D geological framework model (Romine et al., 2020), were used in this study to accurately define the boundaries of structural elements. Existing interpretations and literature were also consulted and combined with the boundary definitions to develop a set of georeferenced polygons or shapefiles, defining the major structural elements of the Victorian Otway Basin: Early Cretaceous depocentres, Late Cretaceous depocentres and platforms, and basement and topographic highs.
From previous publications, consistent naming had been established for most structural elements; however, some elements had multiple names. Most previously identified structural elements were ill-defined with only small-scale illustrations available. The names used to define the structural elements in this study were resolved by considering the evolution of the understanding of the Otway Basin, along with historical precedence and common usage in the literature.
This review of Victorian Otway Basin structural elements provides a detailed set of output files (Attachment A1). These can be used as a consistent reference for future mapping and modelling studies. The structural elements defined in this study are not considered a definitive list. Further refinements should be possible if new data is acquired over areas where data availability limited the interpretation in this study.
Bibliographic reference:
Vujovic, A., Goldie Divko, L.M. & Eid, R., 2021. A review of structural elements, Otway Basin, Victoria. VGP Technical Report 64. Geological Survey of Victoria, Department of Jobs, Precincts and Regions, Melbourne, Victoria.