Stratigraphic correlation of the Devonian sequence in the Blantyre Sub-basin, Darling Basin, western New South Wales∗

∗Data Tables 1–3 [indicated by an asterisk (∗) in the text and listed at the end of the paper] are Supplementary Papers; copies may be obtained from the Geological Society of Australia's website (<http://www.gsa.org.au>) or from the National Library of Australia's Pandora archive (<http://http://www.nla.gov.au/nla.arc-25194>).

Abstract

Seismic sections and the analysis of lithostratigraphic units from well-log data were used to develop a new stratigraphic correlation of the Winduck, Snake Cave and Ravendale Intervals for the Blantyre Sub-basin. The stratigraphic boundaries of the intervals were defined at marked changes in well-log characteristics, and depth estimates of the boundaries were derived from the well-log data in Mt Emu 1, Blantyre 1 and Kewell East 1. Six seismic-stratigraphic boundaries have been identified in the seismic sections to show the continuity of the latest Silurian to Holocene sediments throughout the Blantyre Sub-basin; from bottom to top they are: H-1, base of the Winduck Interval; H-2, base of the Snake Cave Interval; H-3, base of the Ravendale Interval; H-4/5 base of the undifferentiated Upper Carboniferous/Permian sediments; and H-6 base of the undifferentiated Cenozoic sediments. All stratigraphic boundaries are based on good continuous markers, with strong amplitudes throughout the whole sub-basin. A three-dimensional geological model was developed from the seismic data to map out the geometry of the key reflectors, and hence the structure and stratigraphy of the Winduck, Snake Cave and Ravendale Intervals in the areas where these intervals have been preserved. This model has better defined the Wilcannia High and two smaller highs around the Mt Emu 1 and Snake Flat 1 wells, and further defines the relationships between the stratigraphy, sub-basin geometry and development of complex structures in the Blantyre Sub-basin.

Key Words:

• Blantyre Sub-basin
• Darling Basin
• Devonian
• gravity data
• seismic data
• Silurian
• stratigraphy
• surface geology
• well-log analysis

Acknowledgements

This paper is based on a PhD study at the University of New South Wales, supported by a scholarship from the Libyan Government, through the Department of Geology, Faculty of Science, 7th April University in Zawia, western Libya. Thanks are expressed to the New South Wales Department of Primary Industries (Minerals) for suggesting the research, and for provision of the seismic profiles, wireline logs and gravity data. In particular, thanks are expressed to Senior Geophysicist Phillip Cooney, Exploration Manager with Red Sky Energy Pty Ltd for advice and helpful comments related to the study area and regional stratigraphy. Thanks are also due to the School of Biological, Earth and Environmental Sciences, University of New South Wales, for access to the Kingdom™ suite of processing and presentation software, and to Derecke Palmer, who acted as co-supervisor for the project. We thank journal reviewers Gordon Packham, Kingsley Mills for their comments, from which the paper has greatly benefited.

Notes

∗Data Tables 1–3 [indicated by an asterisk (∗) in the text and listed at the end of the paper] are Supplementary Papers; copies may be obtained from the Geological Society of Australia's website (<http://www.gsa.org.au>) or from the National Library of Australia's Pandora archive (<http://http://www.nla.gov.au/nla.arc-25194>).