The distribution and morphology of Late Jurassic to Early Cretaceous igneous intrusions in the Northern Carnarvon Basin
Michael Curtis A * , Simon Holford A , Mark Bunch A , Nick Schofield B and Alex Karvelas CA University of Adelaide, Adelaide, SA, Australia.
B University of Aberdeen, Aberdeen, Scotland.
C SLB, Perth, WA, Australia.
The APPEA Journal 63 S221-S226 https://doi.org/10.1071/AJ22096
Accepted: 24 February 2023 Published: 11 May 2023
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of APPEA.
Abstract
The Northern Carnarvon Basin (NCB) contains extensive networks of igneous intrusions emplaced during Late Jurassic and Early Cretaceous rifting that led to the breakup of the Greater India from Australia. We present the first basin-wide study of the distribution and morphology of these igneous intrusions through the interpretation of regionally extensive 3D and closely spaced 2D seismic data across the Exmouth Plateau and Exmouth Sub-basin. We observe three dominant intrusion morphologies: (1) Saucer-shaped intrusions up to ~20 × 40 km, but commonly much smaller, present in Jurassic strata of the southern Exmouth Plateau and central Exmouth Sub-basin; (2) Large, stacked, strata parallel, sheet intrusions, often >100 km in length, dominant in Triassic strata in the Exmouth Plateau and southern Exmouth Sub-basin; and (3) Variably sized, predominantly strata parallel and occasionally fault hosted intrusions (ranging in dimension from ~5 × 8 to ~35 × 65 km) present in Jurassic rocks in the Exmouth Sub-basin, and uppermost Triassic rocks in the Exmouth Plateau. We suggest that the morphologies of intrusions in the NCB are predominantly controlled the mechanical properties of their host rocks.
Keywords: 3D seismic, Exmouth Plateau, Exmouth Sub‐basin, intrusion mapping, intrusion morphology, intrusions, magma emplacement, Northern Carnarvon Basin, petroleum exploration, sills.
Michael Curtis is currently completing his PhD on the impact of magmatism on Carnarvon Basin petroleum systems at the Australian School of Petroleum and Energy Resources in Adelaide, whilst working full-time with Santos in the Operations Geomechanics team based in Brisbane. |
Professor Simon Holford is South Australian State Chair of Petroleum Geoscience at the Australian School of Petroleum and Energy Resources, University of Adelaide. |
Dr Mark Bunch is a Senior Lecturer in Petroleum Geoscience at the Australian School of Petroleum and Energy Resources, University of Adelaide, South Australia. |
Dr Nick Schofield is a Reader in Igneous and Petroleum Geology at the University of Aberdeen, UK. |
Alex Karvelas is the Exploration Lead for the Exploration Data Australasia region at SLB, based in Perth. |
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