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Duntroon Sub-basin

Entity ID: 27358 Compiled by: Bradshaw, B.E. Year: 2002 Status: Defined

Last Revised: 2013

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

Synonyms: Duntroon Basin, Inner Duntroon Basin Symbol: NA

Minimum age: Maastrichtian Age method: inferred, biostratigraphic correlation

Maximum age: Middle Jurassic Age method: inferred, seismic interpretation

Summary: The Duntroon Sub-basin of the Bight Basin is a rift basin on the continental shelf and slope containing a Jurassic to Upper Cretaceous sedimentary succession up to 10 km in thickness.

Attributes:
Area (square kilometres): 12000
State: SA
Minimum present water depth (m): 100
Maximum present water depth (m): 2500
Main rock types: siliciclastic sediments and sedimentary rocks
Main depositional environment: marine and non-marine
Minimum sediment thickness (m): 0
Maximum sediment thickness (m): 10000
overlain by up to 2000 m of Cainozoic strata
Present crustal setting: continental
Country: AUS

Parent: Bight Basin

Child Provinces: No data

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

Constituent units: Borda Formation, Ceduna Formation, Echidna Formation, Platypus Formation, Wombat Sandstone Member, Neptune Formation, Wigunda Formation (absent throughout most of Duntroon Sub-basin), Potoroo Formation, Hammerhead Supersequence, Tiger Supersequence, White Pointer Supersequence, Blue Whale Supersequence, Bronze Whaler Supersequence, Southern Right Supersequence, Minke Supersequence, Sea Lion Supersequence

Events: Eyre extension, Ceduna extension, Southern Margin Late Cretaceous and Cenozoic magmatism, 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: Minage based on recoginition of upper T. longus spore-pollen zone and intra M. druggii dinocyst zone

Overview: The Middle Jurassic to Late Cretaceous (Maastrichtian) Duntroon Sub-basin is a half-graben complex on the continental shelf and upper slope (100 to 1000m water depth) in offshore South Australia. The Duntroon Sub-basin has been reclassified as one of a series of four half-graben depocentres inboard of the main rift system of the Bight Basin, superseding the former terminology of the Duntroon Basin. Only three exploration wells have been drilled in the Duntroon Sub-basin, with no commercial discoveries (Dec 2003). The Duntroon Sub-basin developed during a period of Middle Jurassic to Early Cretaceous extension and Early Cretaceous thermal subsidence. It was also modified by inversion tectonics during the Late Santonian break-up of Australia and Antarctica. The Duntroon Sub-basin contains a largely siliciclastic, Mesozoic sedimentary succession up to 10 km in thickness. This is unconformably overlain by up to 2 km of a mixed siliciclastic to carbonate, Tertiary-aged section assigned to the Eucla Basin. The basal Jurassic basin-fill of the Duntroon Sub-basin is poorly known, with most information inferred from seismic reflection images. Lower Cretaceous (Berriasian-Albian) fluvial, lacustrine and coastal plain sediments are widespread and overlie inferred Jurassic-aged fluvial and lacustrine sediments. Upper Cretaceous marine sediments are generally either thin or absent throughout the Duntroon Sub-basin. Upper Jurassic to Lower Cretaceous syn-rift lacustrine shales from the Echidna Formation are considered the main potential source rock in the Duntroon Sub-basin, while coals from the Upper Borda Formation may also have some source rock potential. Structural traps associated with tilted fault blocks, drape anticlines and inversion anticline structures are the main potential exploration targets. Evidence for hydrocarbon generation and migration in the Duntroon Sub-basin are some minor gas and oil shows at Echidna 1, and hydrocarbon seeps interpreted from ALF and SAR anomalies.

Images: Eastern Bight Basin structural elements and cross-section location map (82 KB), Eastern Bight Basin regional cross-section Profile 7 (57 KB), Bight Basin sequence stratigraphy and basin phases (61 KB)

Other media: No data

Source Information:

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This report was generated on Sunday, August 31, 2014 2:29:13 PM EST.