A preliminary geological survey of the Loppen district, West Finnmark.

The area includes the western margin of the Seiland petrogra phic province and the meta-sedimentary succession to the west. The principal rock types and structures are described and the origin of the metaigneous rocks is discussed. The meta-sedimentary succession is quartzite, overlain by pelitic schist, overlain by meta-limestones. Three generations of structures are recognised, with trends of N 20°, N 340° and N 90° respectively. The succession is metamorphosed to the almandine -- amphibolite facies by regional metamorphism with local contact metamorphism near the gabbro sheets.

The western extremity of the Seiland petrographic province consists of thick alternating sheets of hypersthene gabbro and quartz-feldspar-garnet gneiss belonging to the granulite facies, an olivine gabbro, basic dykes, peridotite dykes, an ultrabasic complex of peridotite blocks in an anorthosite matrix, and a perthosite. It is suggested that a banded and granulated hypersthene gabbro which contains hands of meta-limestone and syenite represents a portion of the intrusive hypersthene gabbro, granulated by penetrative deformation.