Wallaby Plateau
Entity ID: 544639 Compiled by: Nelson, G. Year: 2011 Status: Informal
Last Revised: 2013
Rank: Province Type: sedimentary Subtype: undefined Location: WA Off-shore
Synonyms: Cuvier Plateau Symbol: NA
Minimum age: Recent Age method: inferred, seismic interpretation
Maximum age: Oxfordian Age method: inferred, biostratigraphic correlation
Summary: The Wallaby Plateau is a large submarine plateau located 450 km west of Carnarvon, WA. It is interpreted to have a continental basement overlain by more than 7 km of predominantly volcanic and vocaniclastic rocks.
Attributes:
Area (square kilometres): 109755 State: WA Minimum present water depth (m): 2200 Maximum present water depth (m): 5500 Main rock types: sediments and sedimentary rocks with volcaniclastic debris Main depositional environment: marine Minimum sediment thickness (m): 0 Maximum sediment thickness (m): 7000 Present crustal setting: unknown Country: AUS Tectonic environment: plateau
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Relationships: None
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Key Reference: Sayers, J., Borissova, I., Ramsay, D., Symonds, P.A. 2002, Geological framework of the Wallaby Plateau and adjacent areas, Geoscience Australia. Record, 21, 85p + Plates 1-6 (in pockets) (Refid:24351)
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Overview: The Wallaby Plateau is an expansive bathymetric high located 450 km west of Carnarvon, WA, largely within the Australia's extended continental shelf. It lies in water depths of 2,200 m to greater than 5,000 m and covers approximately 100,000 km2. The Plateau comprises a large bathymetric high in the southeast and a smaller high, Quokka Rise, in the northwest. It is bordered to the north by the Cuvier Abyssal Plain and in the south by the Perth Abyssal Plain. The Wallaby Saddle to the east is a bathymetric low separating the Wallaby Plateau from the western Australian margin. Two prominent volcanic ridges extend from the northern part of the plateau into the Cuvier Abyssal plain (Sonja and Sonne ridges). The south-western parts of these ridges are embedded into the plateau.
Previous interpretations of the Wallaby Plateau based on seismic reflection and potential field data proposed that it is a composite feature cored by areas of extended continental crust that have been modified and blanketed by voluminous volcanic rocks. This volcanism occurred during continental breakup between Australia and Greater India and the development of the lithospheric-scale Wallaby-Zenith Fracture Zone along the southern margin of the plateau.
Recent Geoscience Australia (2008-2009) seismic data in the area confirmed the presence of thick stratified sequences beneath the Lower Cretaceous break-up unconformity interpreted as volcaniclastic successions. On some lines deeper reflectors potentially image Mesozoic or Paleozoic successions. Samples of Lower Cretaceous and Jurassic sedimentary rocks collected from the margin of the plateau suggest that depocentres may have existed on the plateau prior to the onset of breakup-related magmatism. Newly collected gravity and magnetic data supports the continental origin of the plateau. Hydrocarbon prospectivity is considered to be low due to pervasive volcanism throughout the plateau.
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