2200 million years of crustal evolution: The Baltic Shield

The crustal history of the Baltic shield is interpreted in the light of the plate tectonic concept. Five tectonic cycles, each characterized by special lithological and structural features, are distinguished: The Early Archean (> 2900 Ma), the Late Archean (2900‒2500 Ma) and the Svecokarelian (2100‒1750 Ma) cycle, the Southwest Orogen (1750‒1550 Ma) and the Sveconorwegian cycle (1200‒1000 Ma). The Early Archean ensialic basement of Late Archean greenstone belts in the eastern-central part of the shield is alleged to have formed the nucleus, with new crustal addition to the east during the Late Archean cycle. During the Svecokarelian cycle a diversified geosynclinal system developed on a passive continental margin west of the Archean craton. New continental crust has been generated by accretion west of this margin during the Svecokarelian cycle and the Southwest orogeny by subduction of proto-oceanic crust. Considerable reactivation of the Archean craton during Early Proterozoic times is manifested by rifting, layered intrusions, continental volcano-sedimentary belts and granitoidic diapirism. The Sveconorwegian cycle has reworked crust formed earlier producing only minor amounts of juvenile crust. The position of the Baltic shield within the Precambrian of northern and eastern Europe and in the pre-Alpine crust of western Europe is reviewed.

Abstract licence: CC BY-NC

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.