The structure of the Dalradian rocks in the SW Highlands of Scotland

Abstract

The structure of the Dalradian rocks between the Loch Skerrols Thrust and the Highland Boundary Fault in Scotland is related to a regional deformation history of eight fold phases. The first four phases are associated with the formation of early, but not necessarily recumbent, folds such as the Islay Anticline, the Loeb Awe Syncline and the Ardrishaig-Aber-foyle Anticline during the primary deformation. The subsequent phases of deformation are related to the development of secondary structures, such as the Tarbert and Ben Ledi Monoforms, which are superposed on the earlier structures. It is argued that the primary structures formed as a result of lateral compression acting at depth. However, as the Ardrishaig-Aberfoyle Anticline reached a high structural level it collapsed towards the southeast under the influence of gravity to form the anticlinal core to the Tay Nappe. This process was continued during the secondary deformation with the development of the Tarbert and Ben Ledi Monoforrns.