The Permian and Carboniferous extensional history of the Northern Carnarvon Basin and its influence on Mesozoic extension

McHarg, Sam; I’Anson, Amy; Elders, Chris

doi:10.1071/aseg2018abm3_1b

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…These sedimentary rocks are comprised of the Locker Shale and Mungaroo Formation, a deltaic depositional system indicating a regressive component of the post‐rift depositional cycle (Adamson et al., 2013; Marshall & Lang, 2013). The Locker Shale, deposited over the TR10.0 SB unconformity (Base Triassic, 252.2 Ma) (Figure 3), is a widespread and mechanically weak unit that reaches >400 m in thickness on the Mermaid Nose and >2 km thickness further to the west (Deng & McClay, 2019a, 2021; Gartrell et al., 2016; McHarg et al., 2018). During the Middle–Late Triassic, increased sediment supply and limited subsidence led to the deposition of the fluvio‐deltaic Mungaroo Formation, a coarsening‐upward unit dominated by sandstones (Adamson et al., 2013).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Some models use only local observations of Early Cretaceous extension in near‐shore sub‐basins (e.g., Driscoll & Karner, 1998; Karner & Driscoll, 1999); while other models lack clear evidence of crustal architecture supported by high‐resolution seismic data (e.g., Etheridge & O’Brien, 1994; Mutter & Larson, 1989; Williamson et al., 1990). Importantly, the lack of direct and detailed investigation of structural and stratigraphic evidence associated with the Late Paleozoic rifting phase has significantly hindered the understanding of regional tectonic development of the NW Shelf of Australia and continental margin architecture (Gartrell, 2000; I’Anson et al., 2019; Langhi & Borel, 2005; McHarg et al., 2018; Paschke et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

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Low‐Angle Normal Faults on the NW Shelf of Australia: Implications for Late Paleozoic Rifting

Deng

McClay

Belgarde³

2022

Tectonics

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Late Paleozoic rifting of the NW Shelf of Australia formed a wide basin that fundamentally controlled the Mesozoic continental rifting and passive margin development; however, structural style associated with this extensional process remains poorly constrained. Here, we integrate high‐resolution seismic data with well data from the proximal domain of the NW Shelf to show that the Mermaid fault system in the eastern Dampier Sub‐basin is a large‐scale (∼80 km long), low‐angle (5–20°) normal fault with up to 10 km offset formed during the Late Paleozoic rifting. In its northern and southern domains, the Mermaid fault has a planar geometry with characteristic extensional structures. In its central domain, seaward‐dipping, domino‐style normal faults in the upper crust extend downward into a highly reflective seismic zone that arches upward to form an elliptical dome. Growth strata in the hangingwall half‐graben and footwall basement reflections indicate that the Mermaid fault initiated as a high‐angle normal fault and was rotated by footwall exhumation during extension. Intrabasement deformation along and below the Mermaid fault is characterized by moderate‐ to high‐amplitude, semi‐continuous seismic reflectors that are distinct from transparent reflection character in the overlying basement unit. Comparison of the Mermaid fault system to well‐studied detachment faults in metamorphic core complex settings reveals striking similarities. We therefore suggest that the Mermaid fault developed as part of a nascent metamorphic core complex with a warm to hot footwall that enabled middle‐lower crustal flow during the Late Paleozoic continental rifting, likely induced by southward subduction of the Paleo‐Tethys Ocean.

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Section: Geological Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low‐Angle Normal Faults on the NW Shelf of Australia: Implications for Late Paleozoic Rifting

Deng

McClay

Belgarde³

2022

Tectonics

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Stratigraphic and structural architecture across the central North West Shelf – implications for Triassic petroleum systems

et al. 2019

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The Triassic succession in the Roebuck Basin and parts of the adjacent sub-basins is the subject of a regional mapping program at Geoscience Australia that addresses stratigraphic and structural aspects of exploration risk. Seismic horizons of regional significance are integrated into a new tectonostratigraphic framework that also includes lithostratigrapy, gross depositional facies and tectonic extension phases. The main Triassic depocentre extends over the Beagle Sub-basin and north-east Exmouth Plateau, with a re-entrant into the Bedout Sub-basin. A smaller north-east oriented depocentre is located over the outer Rowley Sub-basin and extends into the Barcoo Sub-basin. The Triassic succession thins markedly between these depocentres over a regional palaeogeographic high. Above a basal marine mudstone, the Triassic succession is mainly fluvio-deltaic, but outboard the uppermost Triassic succession it is carbonate-rich. The Rowley depocentre is unusual in that it comprises Lower–Middle Triassic volcanics and Middle–Upper Triassic carbonate-rich facies. Syn-depositional half graben in the Barcoo Sub-basin extend part-way into the adjacent Roebuck Basin. The Roebuck Basin structural architecture is simpler than the neighbouring sub-basins. The contiguous development of fluvio-deltaic facies across the main Triassic depocentre indicates that the Middle Triassic petroleum system may extend beyond the Bedout Sub-basin. Syn-depositional extension may have formed isolated sub-basins favourable for source rock deposition in the Barcoo Sub-basin. The Triassic carbonate play may also be of interest, as carbonate build-ups are locally well imaged in seismic profiles.

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Multiphase Deformation of the Northern Carnarvon Basin

Elders

2018

ASEG Extended Abstracts

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The Permian and Carboniferous extensional history of the Northern Carnarvon Basin and its influence on Mesozoic extension

Cited by 6 publications

References 3 publications

Low‐Angle Normal Faults on the NW Shelf of Australia: Implications for Late Paleozoic Rifting

Low‐Angle Normal Faults on the NW Shelf of Australia: Implications for Late Paleozoic Rifting

Stratigraphic and structural architecture across the central North West Shelf – implications for Triassic petroleum systems

Multiphase Deformation of the Northern Carnarvon Basin

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