Movement and mineralization in the Tyndrum Fault Zone, Scotland and its regional significance

Major and minor fracture analysis of the Tyndrum Fault Zone, Scotland, reve als a late Silurian history of transtensional deformation with opening acro ss the tone as well as left-lateral strike-slip movements. The extensional phases are characterized by hydrothermal quartz veins and breccias associat ed with the early stages of precious-metal mineralization. The strike-slip movements are characterized by cataclastic textures and are associated with the later stages of the precious-metal mineralization. Further transtensio nal deformation in the Carboniferous is indicated by right-lateral strike-s lip movements, associated with fractures throughout the rone containing bot h cataclastic and extensional hydrothermal quartz veins: the quartz veins a re associated with base-metal mineralization. The pre-Devonian, WSW-ENE-dir ected, transtensional deformation of the zone is extrapolated to the whole Dalradian Terrane, the driving force being the gravitational collapse of th e orogenic well parallel to the tectonic trend. The necessary area increase is signified by the intrusion of the end-Caledonian granitic magmas and qu artz-veins. The Carboniferous right-lateral movements resulting from N-S ex tension are related to similar movements, also transtensional, on the Great Glen Fault Zone and in the Midland Valley; the associated mineralization i s related ro a broader Dinantian base-metal mineralizing event.