Nature of the Cuvier Abyssal Plain crust, offshore NW Australia

Reeve, Matthew M.; Magee, Craig; Bastow, I. D.; McDermott, Carl; Jackson, Christopher; Bell, Rebecca; Prytulak, Julie

doi:10.31223/x5202s

Cited by 8 publications

(36 citation statements)

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“…Ma (e.g., Helby et al 1987;Arditto 1993;Labutis 1994;Smith et al 2015;Paumard et al 2018). Developing previous work, a recent examination of the nature and age of the Cuvier Abyssal Plain, adjacent to part of the North Carnarvon Basin, has shown continental breakup of NW Australia involved a protracted (~6 Myr) period of continent-ocean transition zone (COTZ) formation immediately before full lithospheric rupture occurred ~130 Ma (Reeve et al 2021). Although the three unconformities studied here have been broadly linked to continental breakup (e.g., Helby et al 1987;Arditto 1993;Labutis 1994;Smith et al 2015;Paumard et al 2018), the tectonic processes driving their formation remain poorly understood.…”

Section: Introductionmentioning

confidence: 93%

“…These constraints on lava emplacement and genesis suggest the Cuvier Abyssal Plain may actually be part of the Cuvier COTZ, as opposed to fully oceanic crust (Fig. 2) (Reeve et al 2021). If the Cuvier Abyssal Plain is part of a COTZ, the oldest magnetic anomaly recorded in adjacent unambiguous oceanic crust (i.e.…”

Section: Cuvier Marginmentioning

confidence: 99%

“…In this study, we principally consider the Tithonian-to-Hauterivian phase of rifting that led to continental breakup between Australia and Greater India (Fig. 3A) (e.g., Falvey & Veevers 1974;Willcox & Exon 1976;Larson et al 1979;Stagg & Colwell 1994;Longley et al 2002;Stagg et al 2004;Heine & Müller 2005;Robb et al 2005;Direen et al 2008;Reeve et al 2021).…”

Section: Geological Settingmentioning

confidence: 99%

“…Recognition of magnetic chrons M10N-M5n within assumed oceanic crust of the Cuvier Abyssal Plain has been used to suggest that breakup and lithospheric rupture of the Cuvier Margin had occurred by ~136 Ma (Valanginian; Figs 2B and 3A) (Falvey & Veevers 1974;Larson et al 1979); this model implies breakup of the Cuvier Margin occurred ~5 Myr before breakup of the Gascoyne Margin (Reeve et al 2021). However, Reeve et al (2021) recently recognised seaward-dipping reflector (SDR) sequences, which likely correspond to stacked lava flows, across the Cuvier Abyssal Plain. Based on sedimentological, biostratigraphic, and geochemical data, Reeve et al (2021) infer these lava sequences were extruded within subaerial-to-shallow marine conditions and may have been contaminated by continental material.…”

Section: Cuvier Marginmentioning

confidence: 99%

“…However, Reeve et al (2021) recently recognised seaward-dipping reflector (SDR) sequences, which likely correspond to stacked lava flows, across the Cuvier Abyssal Plain. Based on sedimentological, biostratigraphic, and geochemical data, Reeve et al (2021) infer these lava sequences were extruded within subaerial-to-shallow marine conditions and may have been contaminated by continental material. These constraints on lava emplacement and genesis suggest the Cuvier Abyssal Plain may actually be part of the Cuvier COTZ, as opposed to fully oceanic crust (Fig.…”

Section: Cuvier Marginmentioning

confidence: 99%

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The stratigraphic record of continental breakup, offshore NW Australia

Magee¹,

Reeve²,

Jackson³

et al. 2021

Preprint

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Continental breakup involves a transition from rapid, fault-controlled syn-rift subsidence to relatively slow, post-breakup subsidence induced lithospheric cooling. Yet the stratigraphic record of many rifted margins contain syn-breakup unconformities, indicating episodes of uplift and erosion interrupt this transition. This uplift has been linked to mantle upwelling, depth-dependent extension, and/or isostatic rebound. Deciphering the breakup processes recorded by these unconformities and their related rock record is difficult because associated erosion commonly removes the strata that help constrain the onset and duration of uplift. We examine three major breakup-related unconformities and intervening rock record in the Lower Cretaceous succession of the Gascoyne and Cuvier margins, offshore NW Australia, using seismic reflection and borehole data. These data show the breakup unconformities are disconformable (non-erosive) in places and angular (erosive) in others. Our recalibration of palynomorph ages from rocks underlying and overlying the unconformities shows: (i) the lowermost unconformity developed between 134.98–133.74 Ma (Intra-Valanginian), probably during the localisation of magma intrusion within continental crust and consequent formation of continent-ocean transition zones (COTZ); (2) the middle unconformity formed between ~134–133 Ma (Top Valanginian), possibly coincident with breakup of continental crust and generation of new magmatic (but not oceanic) crust within the COTZs; and (iii) the uppermost unconformity likely developed between ~132.5–131 Ma (i.e. Intra-Hauterivian), coincident with full breakup of continental lithosphere and the onset of seafloor spreading. During unconformity formation, uplift was focused along the continental rift flanks, likely reflecting landward flow of lower crustal and/or lithospheric mantle from beneath areas of localised extension towards the continent (i.e. depth-dependent extension). Our work supports the growing consensus that the ‘breakup unconformity’ is not always a single stratigraphic surface marking the onset of seafloor spreading; multiple unconformities may form and reflect a complex history of uplift and subsidence during the development of continent-ocean transition.

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Section: Introductionmentioning

confidence: 93%

Section: Cuvier Marginmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Cuvier Marginmentioning

confidence: 99%

Section: Cuvier Marginmentioning

confidence: 99%

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The stratigraphic record of continental breakup, offshore NW Australia

Magee¹,

Reeve²,

Jackson³

et al. 2021

Preprint

Self Cite

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Magmatic rifting in the Main Ethiopian Rift began in thick continental lithosphere; the case of the Galema Range

Chiasera

Rooney

Bastow

et al. 2021

Lithos

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Seismic Reflection Data Reveal the 3D Subsurface Structure of Pit Craters

et al. 2022

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Pit craters are quasi‐circular depressions observed on rocky and icy planetary bodies, as well as numerous asteroids. Pit craters are thought to form by overburden collapse into a subsurface cavity or volumetrically depleted zone. Importantly, the surface size and distribution of pit craters may provide an important record of otherwise inaccessible subsurface processes. However, because we cannot access the subsurface of many planetary bodies, we rely on physical and numerical models to infer processes linked to pit crater formation. Here, we use 3D seismic reflection data to quantify the palaeosurface and subsurface geometry of 59 Late Jurassic pit craters buried to depths of ∼3 km within a sedimentary basin, offshore NW Australia. The pit craters are typically funnel‐like, with an inverted conical upper section underlain by a pipe. Pit crater depths, that is, the height of inverted cone sections, correlate with their plan‐view length, consistent with observations of pit craters elsewhere; this trend is rendered less apparent by later sediment‐infilling. For the first time, we show some pit crater pipes connect to underlying igneous dikes or steeply dipping, likely dilatational portions of normal faults. Although some pit craters seemed to have formed due to faulting and others to dyking, they cannot be differentiated based on their surface expression. Our data also suggest pit crater size may not relate to the mechanical properties of the host material. Overall, we conclude that the surface expression of pit craters on Earth and other planetary bodies may not be diagnostic of subsurface processes or properties.

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Nature of the Cuvier Abyssal Plain crust, offshore NW Australia

Cited by 8 publications

References 0 publications

The stratigraphic record of continental breakup, offshore NW Australia

The stratigraphic record of continental breakup, offshore NW Australia

Magmatic rifting in the Main Ethiopian Rift began in thick continental lithosphere; the case of the Galema Range

Seismic Reflection Data Reveal the 3D Subsurface Structure of Pit Craters

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