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Journal of Australian Energy Producers
RESEARCH ARTICLE (Open Access) (Non peer reviewed)

A new perspective on regional structural architecture across the offshore Otway Basin

Chris Nicholson A * , Steve Abbott A , George Bernardel A and Yvette Poudjom Djomani A
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A Geoscience Australia, Canberra, ACT, Australia.




Chris Nicholson graduated with a BSc (Hons) in Geology from the Australian National University in 2000. He joined Geoscience Australia in 2004 as Basin Analyst and Structural Geologist working on regional prospectivity studies of Australia’s offshore basins. Chris is a member of PESA and SEAPEX, and is a past president of PESA ACT.



Steve Abbott holds a PhD degree in sedimentary geology from James Cook University. He joined Geoscience Australia in 2013 where he works as a Basin Analyst on regional studies of Australia’s offshore basins. Steve is a member of PESA and SEPM, and is past president of PESA ACT.



George Bernardel gained his BSc (Honours) in Geophysics from the University of Sydney in 1986. He joined Geoscience Australia in 1995 where he works as a Basin Analyst on Australia’s offshore basins. He is currently mapping Cretaceous–Cenozoic sequences and structure across the offshore Otway Basin.



Yvette Poudjom Djomani completed a PhD in geophysics at the University of Paris XI (France) and earned an MBA from the Australian Institute of Business (Adelaide). She joined Geoscience Australia in 2016 where she works as a Potential Field Geophysicist. Yvette is currently working on depth to basement modelling of the Deep-water Otway Basin. She is a member and Treasurer of ASE.

* Correspondence to: Chris.Nicholson@ga.gov.au

Australian Energy Producers Journal 64 S416-S422 https://doi.org/10.1071/EP23201
Accepted: 22 February 2024  Published: 16 May 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of Australian Energy Producers. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Geoscience Australia has undertaken a regional seismic mapping study of the offshore Otway Basin extending across the explored inner basin to the frontier deep-water region. Seismic interpretation covers over 18,000 line-km of new and reprocessed data acquired in the 2020 Otway Basin seismic program and over 40,000 line-km of legacy 2D seismic data. We present new basin-scale isochore maps that show the distribution of the Cretaceous depocentres. Maps for the Lower Cretaceous Crayfish and Eumeralla supersequences, together with those recently published for the Upper Cretaceous Shipwreck and Sherbrook supersequences, complete the set of isochore maps for the main tectonostratigraphic basin intervals. Mapping of basement-involved faults has revealed structural fabrics that have influenced depocentre development. The tectonostratigraphic development of depocentres and maps of deep crustal units delineate crustal thinning trends related to late Cretaceous extension phases. This work highlights the need to review and update structural elements. For example, the boundary between the Otway and Sorell basins is now geologically constrained. The refinements to the tectonostratigraphic evolution of the Otway Basin presented here have important implications for the distribution and potential maturity of petroleum systems, especially with regard to heat flow associated with crustal extension.

Keywords: basement, basin boundaries, Eumeralla Supersequence, Otway Basin, reflection MOHO, Sherbrook Supersequence, Shipwreck Supersequence, structural architecture, top lower laminated crust.

Biographies

EP23201_B1.gif

Chris Nicholson graduated with a BSc (Hons) in Geology from the Australian National University in 2000. He joined Geoscience Australia in 2004 as Basin Analyst and Structural Geologist working on regional prospectivity studies of Australia’s offshore basins. Chris is a member of PESA and SEAPEX, and is a past president of PESA ACT.

EP23201_B2.gif

Steve Abbott holds a PhD degree in sedimentary geology from James Cook University. He joined Geoscience Australia in 2013 where he works as a Basin Analyst on regional studies of Australia’s offshore basins. Steve is a member of PESA and SEPM, and is past president of PESA ACT.

EP23201_B3.gif

George Bernardel gained his BSc (Honours) in Geophysics from the University of Sydney in 1986. He joined Geoscience Australia in 1995 where he works as a Basin Analyst on Australia’s offshore basins. He is currently mapping Cretaceous–Cenozoic sequences and structure across the offshore Otway Basin.

EP23201_B4.gif

Yvette Poudjom Djomani completed a PhD in geophysics at the University of Paris XI (France) and earned an MBA from the Australian Institute of Business (Adelaide). She joined Geoscience Australia in 2016 where she works as a Potential Field Geophysicist. Yvette is currently working on depth to basement modelling of the Deep-water Otway Basin. She is a member and Treasurer of ASE.

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