The junction between Jurassic sandstones and Tertiary granophyre near Dunan, Isle of Skye: a re-interpretation

Abstract

The contact of the Red Hills granophyre with the Inferior Oolite sandstones on its eastern margin was described from exposures on the shore near Dunan by T. C. Day (1931), who concluded that the granophyre had intruded and metasomatised the sandstones. From a re-examination of Day’s specimens and thin-sections, however, the writer inferred that the contact was a fault plane; further investigation in the field and in the laboratory has confirmed this conclusion and has suggested that streams of hot gas passed upwards along the fault plane. The enrichment of the fragmental rocks developed along the fault plane in Fe, Mg, Ti and OH, seen from Day’s analyses, is ascribed to the action of the ascending gases.