Cullen - Troup Head, Banffshire Coast

The classic section through Buchan metamorphism and a key locality of understanding the tectono-thermal evolution of the Grampian terrain.

This very large site extends for 32 km along the north coast of the north-east Grampian Highlands from Cullen Harbour in the west to Troup Head in the east. It comprises a near-complete succession from the Cullen Quartzite Formation at the top of the Grampian Group to the highest parts of the Macduff Formation of the Southern Highland Group. This apparently simple succession is cut by the Portsoy–Duchray Hill Lineament which forms a major stratigraphical, structural and metamorphic break in the middle of the section. The strata young overall from west to east, with only minor local reversals. To the west of the Portsoy–Duchray Hill Lineament, structures are comparable to those of the central Grampian Highlands and are dominated by tight NW-verging folds. Deformation increases dramatically eastwards towards the Portsoy–Duchray Hill Lineament, with most structures becoming largely coplanar and colinear. The wide shear-zone that here marks the lineament contains variably deformed mafic and ultramafic intrusive igneous rocks of the c. 474–470 Ma North-east Grampian Basic Suite. East of the lineament, in the so-called ‘Buchan Block’, the rocks show small- and medium-scale folding, in parts with interference patterns, but the regional outcrop pattern is dominated by the broad, open Turriff Syncline, whose axis plunges gently to the north-north-east. (from Stephenson et al. 2013).