The structural relationships of the Loch Borrolan Complex, Scotland

Abstract

The Borrolan Complex comprises earlier and later rock suites which are separated by an intrusive junction. The earlier suite forms a conformable sheeted complex which has been punched through by a later plug‐like body and includes several distinct magma types; while the later suite differentiated gravitationally in place. Field and microscopic evidence suggests that some of the earlier rocks were emplaced prior to the principal movements on the Assynt Thrust Plane, while the later suite post‐dates the development of the Assynt Thrust, although it is affected by a deformation. It is suggested that the emplacement of the greater bulk of the Borrolan rocks after movement on the Assynt Thrust Plane had ceased excludes the possibility of the Borrolan, and nearby Loch Ailsh, intrusions being the trigger mechanism which set off the great duplication of strata in the Assynt Culmination.