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Denmark Sub-basin

Entity ID: 27364 Compiled by: Bradshaw, B.E. Year: 2003 Status: Defined

Last Revised: 2013

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

Synonyms: Denmark Trough Symbol: NA

Minimum age: Cretaceous Age method: inferred

Maximum age: Jurassic Age method: inferred

Summary: The Denmark Sub-basin is a newly defined component of the western Bight Basin that contains up to 2000 m of inferred Mesozoic sedimentary rocks.

Attributes:
Area (square kilometres): 2300
State: WA
Minimum present water depth (m): 500
Maximum present water depth (m): 3500
Main rock types: siliciclastic sediments and sedimentary rocks
based on analogies with the Eyre Sub-basin
Main depositional environment: marine and non-marine
based on analogies with the Eyre Sub-basin
Maximum sediment thickness (m): 2000
Mesozoic strata only - overlain by 500 m of Cainozoic strata
Present crustal setting: continental
Country: AUS

Parent: Bight Basin

Child Provinces: No data

Relationships:
Adjoins - Recherche Sub-basin
Underlies - Eucla Basin

Constituent units:

Events: No data

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 Denmark Sub-basin is a small (2300 sq. km), newly defined rift basin located on the continental slope of the western Bight Basin in water depths of between 500 and 3500 m. The Denmark Sub-basin is a structurally complex half graben that forms a depocentre for at least 2000 m of inferred Mesozoic sedimentary rocks unconformably overlain by around 500 m of Cainozoic strata from the Eucla Basin. Limited seismic data (two regional lines) from the Denmark Sub-basin indicate the basin fill consists of two rift-sag successions separated by a prominent unconformity corresponding to a significant deformation event. The age and origin of this unconformity is uncertain, however, it may be related to break-up of the southwest continental margin in the Early Cretaceous. The main half-graben structure is difficult to define due to the extensive deformation and truncation of the older rift sag succession. However, the half graben appears to be bounded by an east-northeast striking rift border fault system that forms a prominent scarp on the landward wall of the Wilson Canyon. The basinward boundary between the perched half graben from the Denmark Sub-basin and the downthrown half graben of the Recherche Sub-basin is a major, east-northeast trending intra-rift fault system. To date, no wells have been drilled in the Denmark Sub-basin to constrain the age and lithology of the basin fill. The limited seismic data available suggest that it may have insufficient overburden to generate hydrocarbons. However, additional seismic data needs to be acquired to determine if the Denmark Sub-basin contains a thicker sediment fill, as the deformed older section contains potential structural traps for hydrocarbons.

Images: Western Bight Basin structural elements and cross-section location map (67 KB), Denmark Sub-basin seismic dip line (216 KB)

Other media: No data

Source Information:

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This report was generated on Thursday, August 21, 2014 8:32:33 AM EST.