The offshore extension of the Loch Gruinart Fault, Islay

Abstract

Synopsis A seismic survey has been carried out in the eastern Malin Sea between Colonsay, Islay and the Donegal coast of Eire, and has revealed the presence of major dislocations both to the north and south of Islay. These faults are considered to be the submarine extensions of the Loch Gruinart Fault. It is proposed that the Loch Gruinart Fault is connected to the Leannan Fault in the south-west and to the Great Glen Fault in the north-east. To the south-west of Islay, the fault forms the north-west boundary of a sedimentary basin in which about 1 km of sedimentary rocks (probably Permo-Triassic) is preserved; post-Palaeozoic fault movements appear to be dip-slip.