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Bremer Sub-basin

Entity ID: 435379 Compiled by: Ryan, D. Year: 2007 Status: Defined

Last Revised: 2013

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

Synonyms: NA Symbol: NA

Minimum age: Manumiella druggii Age method: biozone

Maximum age: Murospora florida Age method: biozone

Summary: The Bremer Sub-basin is a offshore frontier basin located on the southwestern margin of Australia that contains up to 9.5 km of Jurassic to Cretaceous sediments.

Attributes:
State: WA
Minimum present water depth (m): 80
Maximum present water depth (m): 4000
Main rock types: siliciclastic sediments and sedimentary rocks
Main depositional environment: marine and non-marine
A suite of both marine and non-marine rocks were sampled during the Bremer Sampling Survey (s265).
Minimum sediment thickness (m): 0
Maximum sediment thickness (m): 9500
Approximately 4.6s TWT of sediment has been interpreted from seismic data.
Present crustal setting: continental
Country: AUS

Parent: Bight Basin

Child Provinces: No data

Relationships:
Adjoins - Recherche Sub-basin
Overlies - Yilgarn Craton
Underlies - Eucla Basin

Constituent units: Bremer 1 (Seismic-stratigraphic Unit), Bremer 2 (Seismic-stratigraphic Unit), Bremer 3 (Seismic-stratigraphic Unit), Bremer 4 (Seismic-stratigraphic Unit), Bremer 5 (Seismic-stratigraphic Unit), Bremer 6 (Seismic-stratigraphic Unit)

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

Mineral Deposits: No data

Key Reference: Bradshaw, B.E. (Editor) 2005, Geology and Petroleum Potential of the Bremer Sub-basin, Offshore Southwestern Australia, Geoscience Australia. Record, 2005/21, (Refid:63143)

Comments: No data

Overview: The Bremer Sub-basin is a Middle Jurassic - Late Cretaceous half-graben complex located in the western part of the Bight Basin. It extends across the continental slope off the southern coast of Western Australia in water depths of 100 - 4000 m. The sub-basin is a rank frontier area for petroleum exploration with no wells previously drilled. Integration of seismic data and dredge samples has identified four main basin phases: a) Late Jurassic upper crustal syn-rift extension leading to the formation of five major half graben; b) Berriasian to Valanginian post-rift thermal subsidence; c) Valanginian to late Aptian reactivated extension, intra-basin half-graben growth and continued thermal subsidence; and, d) late Aptian to Maastrichtian thermal subsidence. Initial terrestrial sedimentation was succeeded by marine deposition in the Aptian prior to break-up of Australia and Antarctica in the Late Cretaceous. Structurally, the sub-basin comprises a series of en-echelon SW-NE trending fault-bounded half graben, and a significant intra-basin fault system that developed during rifting between Australia and Antarctica. Of particular importance to petroleum exploration are three major cycles of lacustrine and fluvial sedimentation in Late Jurassic - Early Cretaceous strata, which provide key petroleum system elements of both organic-rich source rocks to generate hydrocarbons, and sandstones overlain by thick mudstones that could potentially reservoir hydrocarbons. Exploration opportunities and play types vary across the sub-basin. A large potential source kitchen area occurs in the central part of the sub-basin, where sediments are 4 to 9.5 km thick. Here, the main exploration play is fault block traps in water depths of 1000 to >2500 m. Smaller depocentres with up to 5 km of sediment fill occur in the western and eastern parts of the basin and host large anticlinal structures in water depths of 500 to 800 m.

Images: Seismic Line s280/18 (1363 KB), Bremer Sub-basin Bathymetry and Datasets (2614 KB), Basement terrane map of the Bremer Sub-basin (281 KB), Structrual elements map of the Bremer Sub-basin (814 KB), Sediment thickenss map of the Bremer Sub-basin (1422 KB), Seismic Line s280/21 (1987 KB), Seismic Line s280/19 (2132 KB), Seismic Line s280/15 (1916 KB), Bremer Sub-basin Petroleum Systems chart (924 KB), Bremer Sub-basin source rock geochemistry (430 KB), Bremer Sub-basin subsidence and hydrocarbon expulsion diagram (1553 KB), Schematic play diagram for the central Bremer Sub-basin (1119 KB), Schematic play diagram for the western and eastern Bremer Sub-basin (711 KB), Bremer Sub-basin Stratigraphy (1649 KB)

Other media: No data

Source Information:

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This report was generated on Friday, October 31, 2014 12:19:34 AM EST.