The Tay nappe and associated folding in the Ben Ledi–Loch Lomond area

Abstract

Synopsis Recent mapping in the Ben Ledi—Loch Lomond area has shown the southern closure of the Tay nappe to consist of three major folds, the Aberfoyle anticline, Ben Ledi antiform and Benvane synform. The D 1 age of these folds is clearly demonstrated by cleavage-bedding relationships and younging reversals. The previously unrecognised Benvane synform, the structurally lowest major fold, is responsible for the regional inversion of the flat belt. It is defined both on structural and stratigraphical grounds. The D 2 event is dominantly a product of a deformation event in which simple shear increases in intensity downwards. The limit of significant D 2 deformation cuts the major D 1 fold hinges. D 4 is responsible for the Highland Border downbend, the major monoformal structure which divides the area into a flat belt and a steep belt. The steep belt lies adjacent to the Highland Boundary fault and provides a section through the structurally high levels of the Tay nappe.