Rockall Trough

The Rockall Basin (also known as the Hatton Rockall Basin) is a large (c. 800 km by 150 km) sedimentary basin that lies to the west of Ireland and the United Kingdom beneath the major deepwater area known as the Rockall Trough. It is named after Rockall, a rocky islet lying 301.4 km west of St Kilda.

The nature of the crust beneath the Rockall Trough has long been a matter of debate. Originally thought to be oceanic crust it is now generally considered to be highly stretched continental crust, although some groups of researchers continue to favour either oceanic or transitional style crust, particularly at the southern end of the basin.

The Rockall Basin forms part of a chain of highly extended Mesozoic rift basins between the Charlie-Gibb and Senja Fracture Zones, that includes; the Faeroe-Shetland Basin, the Møre Basin, and the Vøring Basin.

There are indications that the Rockall Basin developed within an earlier rift system, which is likely to be of Triassic to Middle Jurassic in age, by analogy with the nearby Slyne-Erris Basins. The age of the main rift phase in the Rockall Basin is strongly debated, with Late Jurassic, Early-, Mid- and Late Cretaceous all being suggested.

To date, there has been comparatively little drilling to explore for oil and gas within the Rockall Basin and only two discoveries have been made, Benbecula in the northern UK Rockall (Shell originally Enterprise Oil) and Dooish in the northern Irish Rockall (Shell originally Enterprise Energy Ireland).

The discoveries show that, at least locally, there is a working petroleum system.

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