Roebuck Basin

Note: refer to the Acreage Release basins page for updated information on the Roebuck Basin

Basin Details and Geological Overview

Previously known as part of the Offshore Canning Basin (prior to 1994), the Roebuck Basin is located on the central North West Shelf between the Northern Carnarvon and Browse Basins and outboard of the Offshore portion of the predominantly Palaeozoic Canning Basin. The Roebuck Basin consists of the Bedout and Rowley Sub-basins.

The Roebuck Basin is one of the least explored offshore basins of the Westralian Super-basin, containing Permian to Cretaceous siliciclastic sediments and Tertiary carbonates.

The Roebuck Basin developed on the North West Shelf as a result of multi-phase rifting on the western flank of the Palaeozoic Canning Basin. The Mesozoic geology of the Roebuck Basin is similar to that of the adjoining Northern Carnarvon and Browse basins, yet the Roebuck Basin is one of the least explored regions of the North West Shelf.

The Roebuck Basin was initiated by northwest-southeast extension in the Late Carboniferous to Early Permian as part of the Westralian Superbasin. Regional uplift and faulting in the latest Permian was associated with volcanism. Thermal sag in the Triassic led to the deposition of a thick sequence of transgressive marine claystone and deltaic deposits. This was followed by a series of transpressional events in the Late Triassic/earliest Jurassic. Early Jurassic extension ultimately led to Callovian breakup in the adjacent Argo Abyssal Plain. Lower and Middle Jurassic sediments represent fluvial and deltaic environments. Callovian break-up resulted in a phase of regional uplift and erosion. Upper Jurassic to Cretaceous sediments grade into a thick section of prograding Cainozoic carbonates.

The Roebuck Basin lacks the thick marine Upper Jurassic source rocks that are found in the inner parts of the Northern Carnarvon Basin to the southwest and adequate source rocks represent a major risk in the basin. However, potential Triassic source rocks have been intersected in wells drilled in the Bedout Sub-basin and on the Bedout High. An additional risk is that the major, trap-forming structural events preceded the main phase of hydrocarbon generation and migration. The primary exploration targets in the basin are Lower to Middle Jurassic deltaic-fluvial sandstones. As yet, no oil or gas discoveries have been made in the Roebuck Basin.

• ProvExplorer - Roebuck Basin Details and Geological Overview

Regional Cross-sections

The location of the seismic cross-section is shown on the Regional structural elements map.

The Rowley Sub-basin, situated on the outer continental margin, comprises a seaward-thickening wedge of Triassic to Recent sediments that are terminated at the continental-oceanic crust boundary by massive down-to-the-northwest faults. The thickest section in the sub-basin comprises six kilometres (4 seconds TWT) of Mesozoic to Recent sediments underlain by nine kilometres (5 seconds TWT) of Palaeozoic sediments.

Roebuck Basin Regional Structural Elements Map

Key references