Synopsis
The Late Laxfordian history of Harris and south-western Lewis is described, on the basis of a primary field survey. The principal event recorded is the development of a complex of granite bodies and migmatites in an older gneiss complex. This migmatite complex has the form of a broad crescentic dome, elongated north-south, of which only the upper portion is exposed. It is younger than most of the fold structures of the region and appears to have developed by the irregular intrusion of potash-rich granite accompanied by local homogenization and granitization of the banded gneisses. The complex is fringed by distinct sheets of granite which are orientated sub-parallel to its roof. The episode of granite intrusion and migmatization was followed by the intrusion of potash-rich pegmatite veins into sub-vertical, east-west trending fissures. The granite-migmatites appear to be similar to the more extensive Svecofennid migmatite complexes of southern Finland. They are late-kinematic in the nomenclature of Eskola (1932) and thus differ from the better known Caledonian granites of Scotland which are chiefly syn-kinematic and post-kinematic.
- © 1971 Scottish Journal of Geology
The Late Laxfordian granite-migmatite complex of western Harris, Outer Hebrides
