EVOLUTION OF LATE ARCHEAN METAMORPHISM OF TUPAYA-BAY, KOVDOZERO-LAKE,NORTHWEST WHITE SEA REGION

The conditions of sequential metamorphic ultrametamorphic events in th e study area varied from moderate- and high-pressure granulite facies to amphibolite facies of the kyanite-sillimanite facial series. A P-T path was calculated for the region using data on fluid inclusions, che mical and fluid composition of rocks, mineral compositions, and minera logical thermometry and barometry. The configuration of the trend is a typical: a pressure increase up to 10 kbar occurred after the high-tem perature ultrametamorphism; then, cooling of the region at a pressure rise up to 11-12 kbar was followed by an isothermic pressure decrease. The further regressive metamorphism path is parallel to CO2 isochores .