Impacts of Neogene-Recent compressional deformation and uplift on hydrocarbon prospectivity of the passive southern Australian margin
Simon Holford A , Richard Hillis A , Ian Duddy B , Paul Green B , Adrian Tuitt A and Martyn Stoker CA Australian School of Petroleum
B Geotrack International Pty Ltd
C British Geological Survey
The APPEA Journal 50(1) 267-286 https://doi.org/10.1071/AJ09016
Published: 2010
Abstract
The passive southern margin of the Australian continent, which formed following Cretaceous–Palaeogene separation from Antarctica, contains a rich record of Neogene–Recent compressional deformation and uplift. This deformation and uplift is manifested by reversal of displacement along syn-rift extensional faults, folding of mid–late Cenozoic post-rift sediments, and regional unconformities that can be traced for distances of up to 1,500 km along the margin. Palaeothermal data from onshore and offshore exploration wells indicate that erosion associated with deformation and uplift locally exceeds 1 km in the eastern Otway Basin. Both neotectonic palaeostress trends inferred from these structures and present-day stress orientations are consistent with northwest–southeast directed compression controlled to first-order by plate boundary forces. The critical role of the relative timing of trap formation and source rock maturation in controlling hydrocarbon prospectivity in the southern Australian margin is investigated by comparing two structures that formed during Neogene–Recent deformation in the Otway Basin: the Minerva and Nerita anticlines. While the Minerva Anticline hosts a major gas field (558 BCF GIP), the Nerita Anticline was found to be dry. A combination of apatite fission track analysis (AFTA), vitrinite reflectance (VR) and present-day temperature data show that all units intersected in Minerva–1 are presently at their maximum post-depositional temperatures, and are presently mature for hydrocarbon generation. In contrast, similar data collected from the preserved section at Nerita–1 indicate cooling from maximum post-depositional temperatures prior to formation of the Nerita Anticline in the late Miocene. Based on regional AFTA data, the underlying early Cretaceous source rocks probably reached maximum palaeotemperatures and ceased hydrocarbon generation during mid-Cretaceous uplift. These results indicate that areas of the southern margin that were deformed during the Neogene–Recent have the greatest potential to trap hydrocarbons where potential source rocks are presently at their maximum post-depositional temperatures.
Simon Holford is an ARC Australian postdoctoral fellow at the Australian School of Petroleum and is deputy director of the Centre for Tectonics, Resources and Exploration (TRaX) at the University of Adelaide. He graduated with a BSc (Hons) from Keele University (2001) and a PhD from the University of Birmingham (2006). His research interests are in the deformation and uplift of rifted margins, sedimentary basins and continental interiors and their impact on hydrocarbon exploration. Member: AGU, ASEG, GSA, GSL, PESA. simon.holford@adelaide.edu.au |
Richard Hillis is CEO of the Deep Exploration Technologies CRC. He graduated with a BSc (Hons) from Imperial College (London, 1985), and a PhD from the University of Edinburgh (1989) and was until recently State of South Australia Professor of Petroleum Geology and Head of the Australian School of Petroleum (University of Adelaide). He has published over 100 papers in the areas of petroleum geomechanics and basin tectonics and has consulted extensively to, and run short courses for, the petroleum industry on these topics. Richard is a non-executive director of JRS Petroleum Research (privately owned image log and geomechanics consultancy), Petratherm (ASX-listed geothermal company) and AuScope (national research facility in the earth sciences). Member: AAPG, AGU, ASEG, EAGE, GSA, GSL, PESA, SEG and SPE. richard.hillis@adelaide.edu.au |
Ian Duddy is a founding Director of Geotrack International Pty Ltd, specialist consultants in thermal history reconstruction for basin modelling. He obtained BSc (Hons) and PhD degrees in geology from the University of Melbourne and has been involved in researching the thermal evolution of sedimentary basins since 1975. Since the incorporation of Geotrack International in 1987 he has been involved in the development and worldwide promotion of AFTA® technologies and their integration with organic thermal indicators to provide rigorous constraints for basin modelling. He is an author of numerous papers on these subjects. Member: AAPG, GSA, PESA and SEPM. mail@geotrack.com.au |
Paul Green is Technical Director of Geotrack International, a private company specialising in thermal history reconstruction in sedimentary basins, and its application to hydrocarbon exploration. He has a PhD from the University of Birmingham, and has held research positions at the Universities of Birmingham and Melbourne, and at University College London. He is the author of over 100 published papers on fission track analysis and related topics. Member: AAPG, PESA and PESGB. |
Adrian Tuitt is a postdoctoral fellow at the Australian School of Petroleum at the University of Adelaide. He graduated from University of Edinburgh with a BSc (Hons) geology degree and a PhD in structural geology. Adrian’s research work involves seismic interpretation and numerical modelling with particular interest in deformation along continental margins and delta systems. Member: PESA. adrian.tuitt@adelaide.edu.au |
Martyn Stoker is a geologist with the Marine Geoscience Programme of the British Geological Survey in Edinburgh, Scotland. He graduated with a BSc (Hons) from Leicester University (1977) and a PhD from the University of Liverpool (1981). His research interests are in the Mesozoic–Cenozoic tectonostratigraphic evolution of the Arctic–northeast Atlantic region, the tectonic, sedimentary and oceanographic development of passive margins, and continental margin glaciation. Member: GSL, Edinburgh Geological Society. mss@bgs.ac.uk |
