Synopsis

In April 2008, 23 attendees of the Highland Workshop visited critical localities of the Scottish Highland Border Complex between Aberfoyle and the Isle of Bute. Widespread existence of fragmental ophicarbonates was confirmed, with the possibility that at least some may have formed as fault gouges in an ocean–continent transition environment similar to those reported from serpentinites in Ligurian-type extensional continent–ocean margins. The consensus view was that amphibolites at Loch Ard and on Bute appear to have been at no higher metamorphic grade than epidote-amphibolite facies. Also that, narrow zones of ‘granitoid rocks’ and spotting in Dalradian rocks in contact with ophicarbonate rocks could represent relatively low Barrovian regional metamorphic temperature effects rather than evidence for contact metamorphism in the sole of an obducted ophiolite. Finally, the Highland Border Ophiolite appears to have originally overlain the Southern Highland and Trossachs groups and was rotated with them by the D4 Downbend Antiform. No evidence was seen at these localities to support the hypothesis that the Highland Border Complex youngs to the NW or did not undergo Grampian deformational events.