%0 Journal Article
%T The Paleoproterozoic Nattanen-type granites in northern Finland and vicinity ¨C a postcollisional oxidized A-type suite
%A Esa Heilimo
%A Jaana Halla
%A Laura S. Lauri
%A O. Tapani R£¿m£¿
%J Bulletin of the Geological Society of Finland
%D 2009
%I The Geological Society of Finland
%X The ~1.8 Ga Nattanen-type granites in the Finnish Lapland and western Kola Peninsula are found as several relatively small, high-level, discordant plutons that are easily discernible as weak maxima on aeromagnetic maps. We present U¨CPb mineral isotope data on the Finnishplutons. The concordia ages are in the 1.79 1.77 Ga range and there is little evidence for inheritance. Initial radiogenic isotope compositions (our common-Pb data combined with previously published whole-rock Nd and Hf data) imply a major, yet varying, Archeansource component. Elemental geochemical data on five Finnish intrusions (the Nattanen stock, the Tepasto and Pomovaara complexes, the Riestovaara and Vainosp   batholiths), as well as associated dyke rocks allow the Nattanen-type granites to be classified as oxidizedA-type granites. Their petrogenesis may be related to partial melting of the lower crust by mafic underplating (extensional setting) or as a result of thermal relaxation in thickened crustal setting.
%K granites
%K A-type granites
%K geochemistry
%K genesis
%K absolute age
%K isotopes
%K U/Pb
%K Pb/Pb
%K Paleoproterozoic
%K Lapland Province
%K Finland
%U http://www.geologinenseura.fi/bulletin/Volume81/Heilimo_etal_2009.pdf