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Abrolhos Sub-basin

Entity ID: 22023 Compiled by: Bradshaw, B.E. Year: 2002 Status: Defined

Last Revised: 2013

Rank: subprovince Type: sedimentary Subtype: polyhistory Location: WA On-shore and off-shore

Synonyms: Abrolhos Province, Inner Abrolhos Sub-basin Symbol: NA

Minimum age: Recent Age method: inferred, biostratigraphic correlation

Maximum age: Early Permian Age method: inferred, biostratigraphic correlation

Summary: The Early Permian to Recent Abrolhos Sub-basin is a mostly offshore, elongate, NNW-trending rift basin located in the northern Perth Basin and contains at least 7000 m of marine to continental sediments.

Attributes:
Area (square kilometres): 15200
State: WA
Minimum present water depth (m): 0
Maximum present water depth (m): 500
Main rock types: siliciclastic sediments and sedimentary rocks
Main depositional environment: marine and non-marine
Maximum sediment thickness (m): 7000
Present crustal setting: continental
Country: AUS

Parent: Perth Basin

Child Provinces: No data

Relationships:
Adjoins - Gascoyne Sub-basin [and former Edel Sub-basin], Houtman Sub-basin, Southern Carnarvon Basin, Turtle Dove Ridge, Vlaming Sub-basin

Constituent units: Barren Sandstone, Cadda Formation, Cardabia Calcarenite, Carynginia Formation, Cattamarra Coal Measures, Kockatea Shale, Korojon Calcarenite, Miria Formation, Toolonga Calcilutite, Tumblagooda Sandstone, Winning Group, Wittecarra Sandstone, Yarragadee Formation, Lesueur Sandstone, Woodada Formation, Irwin River Coal Measures, Eneabba Formation, Beekeeper Formation

Events: No data

Mineral Deposits: No data

Key Reference: Crostella, A. 2001, Geology and petroleum potential of the Abrolhos Sub-basin, Western Australia, Geological Survey of Western Australia. Report, 75, 57p (Refid:23520)

Comments: No data

Overview: The Early Permian to Recent Abrolhos Sub-basin is a NNW-trending rift basin located in the offshore northern Perth Basin. The sub-basin forms part of a complex and extensive poly-phase Permian to Cretaceous rift system along the southwestern Australian margin. 12 exploration wells have been drilled within the sub-basin since 1965 leading to the Dunsborough-1 oil and gas discovery and the Frankland-1 and Perserverance-1 gas discoveries in 2007. The sub-basin overlies the Silurian to Ordovician Tumblagooda Sandstone of the Southern Carnarvon Basin in the north and Proterozoic crystalline basement including the Northampton Complex in the south. Stratigraphic fill in the Abrolhos Sub-basin incorporates a series of Lower Permian to Lower Cretaceous rift-sag successions (6000 m thick) overlain by a thin passive margin cover (up to 850 m thick). However, it is primarily a depocentre for Permian and Triassic strata. The Abrolhos Sub-basin was initiated during Permian rifting when a series of NNW-trending, westerly-downthrown half graben formed and infilled with glacial, marine and continental sediments. Post-rift subsidence during the Late Permian and Early Triassic was associated with the deposition of marine and continental sedimentary rocks. The main depocentre shifted westward into the adjacent Houtman Sub-basin during a Late Triassic and Jurassic rift-sag event, although sediment continued to accumulate in the Abrolhos Sub-basin throughout the Jurassic. The Middle Jurassic to Early Cretaceous break-up of Australia and Greater India produced a complex series of listric-normal faults followed by regional and local uplift and erosion throughout the Abrolhos Sub-basin. Post-break-up deposits have formed a westward thickening passive margin cover of marine clastics and carbonates above the Permian to Lower Cretaceous stacked rift-sag successions. The recent discoveries, a commercial oil discovery at Cliff Head on the ajacent Beagle Ridge, palaeo-oil columns detected in the Cliff Head, Dunsborough, Frankland and Perserverance fields and in dry wells at Flying Foam-1, Hadda-1, Houtman-1, Leander Reef-1, Lilac-1, Livet-1, Mentelle-1, and Morangie-1, along with shows at several stratigraphic levels indicate that much of the Abrolhos Sub-basin has potential for both oil and gas. In particular, there is considerable potential for further discoveries in Permian and Lower Triassic reservoirs sealed by Lower Triassic marine shales (Kockatea Shale), where structural and stratigraphic traps have formed prior to the main period of generation and expulsion from the Abrolhos Sub-basin during the Middle to Late Jurassic.

Images: Perth Basin regional cross-section Profile 1 (53 KB), Perth Basin regional setting and cross-section location map (101 KB), Perth Basin regional cross-section Profile 2 (42 KB), Northern Perth Basin stratigraphy (80 KB)

Other media: No data

Source Information:

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This report was generated on Sunday, November 23, 2014 2:42:33 PM EST.