Seismic Stratigraphy and Passive‐Margin Evolution of the Southern Exmouth Plateau

Boyd, Ron; Williamson, P.; Haq, Bilal U.

doi:10.1002/9781444304015.ch29

Cited by 9 publications

(32 citation statements)

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“…NE-trending) during this time was similar to that of earlier periods (e.g. Boyd et al, 1993;Hull & Griffiths, 2002;Young et al, 2001), with NW-prograding, carbonate-dominated clinoforms observed along the SE basin margin (see Figure 3). Thickness variations in SU-2 reflect growth of the Exmouth Plateau Arch.…”

Section: Interpretation Of Su-2supporting

confidence: 83%

“…truncation, onlap and downlap), and vertical and lateral variations of internal seismic reflection geometry. We identify four seismic facies (see Boyd et al (1993); and (c) SU-3-late Miocene-Present, equivalent to Package 8 of Boyd et al (1993). We mapped five additional horizons within SU-2 within the 3D seismic dataset (Figure 2); these relatively high-amplitude, continuous seismic reflections horizons, which are only locally mappable, define vertical changes in seismic facies and, we infer, depositional locus and process.…”

Section: Data Setmentioning

confidence: 96%

“…Following drilling of ODP Leg 122 wells (i.e. ODP 762 and 763), Boyd et al (1993) updated previous interpretations, providing better lithology and age constraints on the penetrated succession. Our study recognises four regionally significant horizons (Figures 2 and 3) previously identified by Boyd et al (1993).…”

Section: Data Setmentioning

confidence: 99%

“…Haq, 1993;Haq et al, 1992). An unconformity defining the Cretaceous-Palaeogene boundary (Boyd et al, 1993) most probably formed by enhanced bottom-current erosion (Figure 2;Haq et al, 1992) related to the change of primary seafloor spreading axis from the Indian to the Southern Ocean ( Figure 2; Baillie, Powell, Li, & Ryall, 1994). At the start of the Oligocene, a global eustatic sea level fall occurred as a result of continental ice sheet build-up in Antarctica (Miller, Wright, & Fairbanks, 1991).…”

Section: Geological Setting 21 | Tectonostratigraphic Frameworkmentioning

confidence: 99%

“…calcarenite and calcilutite on the shelf and chalk on the plateau), although cores from ODP 762 and 763 indicate calcareous oozes dominate around the Exmouth Plateau Arch. Biostratigraphic data (Supporting Information Figure S1) show that Horizon C defines an unconformity between middle and late Miocene (~9 Ma), equivalent to Reflector 7 of Boyd et al (1993) and N17-1 horizon of Hull and Griffiths (2002).…”

Section: Su-3 (Late Miocene-present)mentioning

confidence: 99%

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Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

et al. 2018

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Deep‐marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation and thermohaline bottom‐currents. Stratigraphic successions can also record plate‐scale tectonic processes (e.g. continental breakup and shortening) that impact long‐term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the Exmouth Plateau, offshore NW Australia, which has been a relatively stable, fine‐grained carbonate‐dominated continental margin from the Late Cretaceous to Present. We combine extensive 2D (~40,000 km) and 3D (3,627 km2) seismic reflection data with lithologic and biostratigraphic information from wells to reconstruct the tectonic and oceanographic evolution of this margin. We identified three large‐scale seismic units (SUs): (a) SU‐1 (Late Cretaceous)—500 m‐thick, and characterised by NE‐SW‐trending, slope‐normal elongate depocentres (c. 200 km long and 70 km wide), with erosional surfaces at their bases and tops, which are interpreted as the result of contour‐parallel bottom‐currents, coeval with the onset of opening of the Southern Ocean; (b) SU‐2 (Palaeocene—Late Miocene)—800 m‐thick and characterised by: (a) very large (amplitude, c. 40 m and wavelength, c. 3 km), SW‐migrating, NW‐SE‐trending sediment waves, (b) large (4 km‐wide, 100 m‐deep), NE‐trending scours that flank the sediment waves and (c) NW‐trending, 4 km‐wide and 80 m‐deep turbidite channel, infilled by NE‐dipping reflectors, which together may reflect an intensification of NE‐flowing bottom currents during a relative sea‐level fall following the establishment of circumpolar‐ocean current around Antarctica; and (c) SU‐3 (Late Miocene—Present)—1,000 m‐thick and is dominated by large (up to 100 km3) mass‐transport complexes (MTCs) derived from the continental margin (to the east) and the Exmouth Plateau Arch (to the west), and accumulated mainly in the adjacent Kangaroo Syncline. This change in depositional style may be linked to tectonically‐induced seabed tilting and folding caused by collision and subduction along the northern margin of the Australian plate. Hence, the stratigraphic record of the Exmouth Plateau provides a rich archive of plate‐scale regional geological events occurring along the distant southern (2,000 km away) and northern (1,500 km away) margins of the Australian plate.

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Section: Interpretation Of Su-2supporting

confidence: 83%

Section: Data Setmentioning

confidence: 96%

Section: Data Setmentioning

confidence: 99%

Section: Geological Setting 21 | Tectonostratigraphic Frameworkmentioning

confidence: 99%

Section: Su-3 (Late Miocene-present)mentioning

confidence: 99%

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Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

et al. 2018

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A natural gas hydrate system on the Exmouth Plateau (NW shelf of Australia) sourced by thermogenic hydrocarbon leakage

Paganoni

King

Foschi

et al. 2019

Marine and Petroleum Geology

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The formation and implications of giant blocks and fluid escape structures in submarine lateral spreads

Jackson

Johnson

et al. 2021

Basin Research

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Lateral spread (or 'spreading') and submarine creep are processes that occur near the headwalls of both terrestrial landslides and submarine mass-transport complexes (MTCs).Both submarine creep and spread deposits may contain giant (km-scale) coherent blocks, but their transport processes remain poorly constrained. Here we use 2D and 3D seismic reflection data to determine the geometry, scale, and origin of an ancient (Late Miocene) mass-transport complex (MTC) located in the Kangaroo Syncline, offshore NW Australia. We show that this large remobilised mass of carbonate ooze is c. 170-300 m thick and covers an area of at least c. 1050 km 2 . The deposit is defined internally by two distinct seismic facies: (i) large, upward-tapering blocks (up to 210-300 m thick, 170-210 m wide, and 800-1200 m long) with negligible internal deformation, which decrease in height and spacing along the transport direction (identical, but in situ, seismic facies forms undeformed slope material immediately updip of the deposit headwall); and (ii) troughs (160-260 m thick, 190-230 m wide and 800-1200 m long) comprising moderately deformed strata, which contain 'v'-shaped, pipe-like structures that extend upwards from the inferred basal shear surface to the top surface of the MTC. The lack of deformation within the blocks, and their correlation to adjacent in-situ deposits, suggests they underwent very limited transport (c. 50 m-70 m). The relatively high degree of deformation within the intervening troughs is attributed to the vertical expulsion of fluids and sediment during hydraulic failure of the sediment mass. We present a hydraulic failure model that accounts for the styles and patterns of intra-MTC deformation process. This model invokes evacuation of the lower slope by a pre-cursor MTC that formed the space to trigger the lateral spread event. Our study provides new insights into the genesis and rheology of subaqueous lateral spreads, enabling improved assessments of the threats posed to critical seafloor infrastructure. The genetic links identified between mass wasting and spatially-focused fluid flow indicate that, as well as disturbing the deep seafloor, submarine landslides may also create important deep-sea biodiversity hotspots.

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Seismic Stratigraphy and Passive‐Margin Evolution of the Southern Exmouth Plateau

Cited by 9 publications

References 0 publications

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

A natural gas hydrate system on the Exmouth Plateau (NW shelf of Australia) sourced by thermogenic hydrocarbon leakage

The formation and implications of giant blocks and fluid escape structures in submarine lateral spreads

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