Origin and metamorphism of iron formations and associated rocks, Lofoten-Vesterålen, N. Norway. I. The Vestpolltind Fe-Mn deposit

Abstract

Geochemical and petrological studies of banded Mn-Fe deposits and associated rocks from Vestpolltind, Lofoten-Vesterålen, show that these rocks may have originated in a marginal sea environment, with intense volcanic and hot spring activity. Mineral analyses have made it possible to calculate the metamorphic conditions during the 1950 m.y. granulite facies metamorphism. Maximum P-T conditions for the regional metamorphism are calculated to 9-11 kb, 770°C, with a local temperature peak of 940±50°C, due to the intrusion nearby of a large mangerite. The stabilities of piemontite and the paragenesis quartz+corundum are discussed. A plate tectonic model for the formation and metamorphism of the rocks is presented. © 1977.