Mellish Rise
Entity ID: 34871 Compiled by: Burch, G. Year: 2003 Status: Informal
Last Revised: 2013
Rank: Province Type: sedimentary Subtype: rift Location: CSIT Off-shore
Synonyms: NA Symbol: NA
Minimum age: Recent Age method: inferred, seismic interpretation
Maximum age: Early Cretaceous Age method: inferred, seismic interpretation
Summary: The Early Cretaceous to Recent Mellish Rise is a large and poorly known submerged block located off northeast Australia in water depths of 150 m to 3000 m.
Attributes:
Area (square kilometres): 31000 State: CSIT Minimum present water depth (m): 150 Maximum present water depth (m): 3000 Main rock types: siliciclastic sediments and sedimentary rocks Speculative Main depositional environment: marine Speculative Minimum sediment thickness (m): 0 Maximum sediment thickness (m): 1000 Present crustal setting: continental Speculative Country: AUS
Parent: No data
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Relationships: None
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Key Reference: Terrill, A. 1975, Submarine Geology of the Northern Lord Howe Rise-Mellish Rise area, Thesis, University of Sydney, (unpublished), , (Refid:12667)
Comments: No data
Overview: The Mellish Rise is a large and poorly known submerged continental block located approximately 600 km off northeast Australia. It occurs near the confluence of a tectonic triple junction between the palaeo Australian, Lord Howe Rise and Louisiade Plateau tectonic plates. This triple junction is believed to have been active between 62 and 52 Ma. The Mellish Rise is highly fractured and has a varied topography. Faulting has formed several graben and half graben that are infilled with up to 1000 m of sediments that appear unconsolidated (transparent) on seismic sections. Several steep-sided intrusions and extrusions are present - the Mellish Reef has grown on a remnant volcano. The Mellish Rise is separated from the eastern margins of the Queensland Plateau and Townsville Trough and the northeastern margin of the Marion Plateau by the bathymetric Cato Trough. The Mellish Rise is separated from the northern Louisiade Plateau by the 190 km wide and 4000 km deep northeast to southwest trending Louisiade Trough. Seismic interpretation coupled with extrapolation from seismic megasequences within the nearby Lord Howe Rise region, have been used to provisionally date the seismic sequences of the Mellish Rise. The uniformity of the basement reflectance across the Mellish Rise and adjacent troughs, suggests that much of the basement may comprise metamorphics. Highly reflective units that overlie basement on parts of the rise are possibly Upper Jurassic volcanics, while the sequences overlying basement elsewhere are interpreted as Lower Cretaceous sediments. An Upper Cretaceous to Eocene sequence onlaps the underlying units and is mostly restricted to graben on the rise and adjacent troughs. An upper-most sequence extends across the Mellish Rise, and is interpreted as Miocene to Recent pelagic oozes, lying above an inferred Eocene to Oligocene regional unconformity.
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Source Information:
- FOR PROVINCE-GENERAL: Sdrolias, M., Muller, R.D., Gaina, C., 2001, Plate tectonic evolution of eastern Australian marginal ocean basins., Eastern Australasian Basins Symposium 2001, 227-237. (Refid: 12544)
- FOR PROVINCE-GENERAL: Terrill, A., 1975, Submarine Geology of the Northern Lord Howe Rise-Mellish Rise area, Thesis, University of Sydney, (unpublished), . (Refid: 12667)
- FOR PROVINCE-GENERAL: Jongsma, D., 1976, A review of the geology and geophysics of the area around Mellish, Frederick, Kenn and Wreck Reefs, and Cato Island., Bureau of Mineral Resources, Record, 76/ 40, . (Refid: 29107)
