METAMORPHIC EVOLUTION OF THE KOLVITSA ANORTHOSITE MASSIF (LAPLAND-KOLVITSA GRANULITE BELT, BALTIC SHIELD)

Abstract

The Kolvitsa metagabbro-anorthosite massif is among eight large Paleoproterozoic massifs of the Lapland-Kolvitsa granulite belt (Baltic Shield). This complex nonuniform plate-shaped body is approximately 2 km thick. From geochronological data the history of the Kolvitsa gabbro-anorthosite massif can be divided into two major periods. The early Paleoproterozoic period was marked by initiation of the rifts with basic-ultrabasic magmatism (2374-2462 Ma), whereas the Svecofennian period was characterized by the collision of the Kola and Belomorian microcontinents (1800-2200 Ma). Each period can be subdivided into subordinate (in duration and scale) stages that reflect certain geodynamic, tectonothermal, magmatic, and metamorphic processes.