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Eyre Sub-basin

Entity ID: 27293 Compiled by: Totterdell, J. and Rollet, N. Year: 2002 Status: Defined

Last Revised: 2013

Rank: subprovince Type: sedimentary Subtype: polyhistory Location: WA, SA Off-shore

Synonyms: NA Symbol: NA

Minimum age: Isabelidinium cretaceum 0di Age method: biozone

Maximum age: Callovian Age method: inferred, biostratigraphic correlation

Summary: The Jurassic to Cretaceous Eyre Sub-basin of the Bight Basin is characterised by a series of east-northeasterly trending en-echelon half graben. It contains a non-marine to marine succession up to 3500 m thick.

Attributes:
Area (square kilometres): 9200
State: WA
State: SA
Minimum present water depth (m): 100
Maximum present water depth (m): 2800
Main rock types: siliciclastic sediments and sedimentary rocks
some coal and organic-rich facies interpreted
Main depositional environment: marine and non-marine
Maximum sediment thickness (m): 3500
overlain by up to 1000 m of Cainozoic strata
Present crustal setting: continental
Country: AUS

Parent: Bight Basin

Child Provinces: No data

Relationships:
Adjoins - Ceduna Sub-basin, Madura Shelf
Underlies - Eucla Basin

Constituent units: Minke Supersequence, Southern Right Supersequence, Bronze Whaler Supersequence, White Pointer Supersequence, Blue Whale Supersequence, Sea Lion Supersequence

Events: Eyre extension, Southern Margin Late Cretaceous and Cenozoic magmatism, Ceduna extension, Australia-Antarctica break-up

Mineral Deposits: No data

Key Reference: Bradshaw, B.E., Rollet, N., Totterdell, J.M., Borissova, I. 2003, A revised structural framework for frontier basins on the southern and southwestern Australian continental margin., Geoscience Australia. Record, 2003/03, 44 (Refid:13490)

Comments: No data

Overview: The Eyre Sub-basin is a perched, Middle Jurassic to Early Cretaceous rift basin located beneath the bathymetric Eyre Terrace in water depths of 100 to 2800 m. It contains up to 3500 m of Mesozoic sedimentary rocks, which in turn are unconformably overlain by up to 1000 m of Cainozoic strata of the Eucla Basin The sub-basin consists of a series of four east-northeast striking half graben that have an en-echelon trend of offset to the southeast. It is bounded by basement highs to the north, west and south, but is probably contiguous with the Ceduna Sub-basin in the east. The Middle Jurassic to earliest Cretaceous fluvio-lacustrine syn-rift succession (Sea Lion and Minke supersequences), is overlain by an Early Cretaceous-age fluvio-lacustrine to shallow marine post-rift fill (Southern Right and Bronze Whaler supersequences). These rocks are overlain by an Early to mid Cretaceous-age marine and deltaic succession (Blue Whale and White Pointer supersequences) that extends beyond the half-graben boundaries. Potential source rock facies include Jurassic lacustrine shales deposited during the syn-rift phase and early post-rift fluvial coals and shales. Evidence of a previous oil accumulation, identified by fluid inclusion studies, is present near the base of Jerboa 1. The hydrocarbons were probably generated from a more deeply buried, syn-rift to early post-rift lacustrine source rocks. The accumulation in Jerboa 1 was breached during a phase of reactivation faulting in the Late Cretaceous. Mature source rocks are likely to be present within the larger half graben in the sub-basin.

Images: Eastern Bight Basin structural elements and cross-section location map (82 KB), Eastern Bight Basin regional cross-section Profile 1 (59 KB), Eastern Bight Basin regional cross-section Profile 2 (68 KB)

Other media: No data

Source Information:

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This report was generated on Thursday, October 23, 2014 7:19:17 PM EST.