MACRO- TO MICRO- SCALE STRUCTURES IN THE ASSYNT REGION OF THE MOINE THRUST BELT

by Dr. Geoffrey E. Lloyd

ST ST LG GT GT Stac of Glencoul Liath Bhad I I CQ CO CQ Loch Glencoul

SITE MAP 1. Looking N from Coire a' Bhaic (Site Map 2) across Loch Glencoul, Assynt, showing the general geological disposition.  A Cambro-Ordovician sedimentary sequence of quartzites (CQ) and sandstones - shales, calc-gritstones and limestones (CO) rests unconformably (u/c) on Archaean Lewisian Gneisses (LG) and is overthrust to the WNW by rocks of the Moine Thrust Zone (ST, Sole Thrust; I, imbricates of CO rocks; GT, Glencoul Thrust of Lewisian Gneisses). The Moine Thrust carrying Precambrian Moine Schists over Cambrian Quartz mylonites outcrops to the right of the map on the Stac of Glencoul.  Select a label-link for more details.

SBF Assynt from Quinag

SITE MAP 2. Looking E from Quinag (Spidean Goinnich) across Loch Assynt and Inchnadamph towards the Moine Thrust Zone, showing the general geological disposition. A Cambro-Ordovician sedimentary sequence of Basal (BQ) and Pipe Rock Quartzites (PQ) and sandstones - shales, calc-gritstones and limestones (UC) rests unconformably (u/c) on Precambrian Torridonian sandstone (T), which in turn is unconformable on Archaean Lewisian Gneisses (LG). The Cambro-Ordovician rocks have been overthrust to the WNW by rocks of the Moine Thrust Zone (ST, Sole Thrust; I, imbricates of CO rocks; GT, Glencoul Thrust of mylonitised Lewisian Gneisses and quartzites). The Moine Thrust carrying Precambrian Moine Schists over Cambrian Quartz mylonites outcrops in the far distance (not seen). Select a label-link for more details - especially SBF, the Skiag Bridge back thrust fault, to see the development of cataclastic fault rocks.

360 panorama of Coire a' Bhaic area, Assynt, showing the general geological dispositionLarge, slow loading image.

Copyright School of Earth and Environment, University of Leeds