Geochemical evolution of the Ivigtut granite, South Greenland: a fluorine-rich "A-type" intrusion

The Ivigtut alkali granite stock lies within the Proterozoic Gardar alkalin e igneous province of South Greenland. This small (300 m across) granite bo dy once contained the world's largest body of cryolite, now mined out. The granite surrounding the cryolite body has been extensively metasomatised by F- and CO2-rich fluids, leading to zonal enrichment in HFSE and REE. Varia tions in the Rb-Sr and Sm-Nd systematics of the granite can be correlated w ith the degree of metasomatism. Unaltered granites have highly variable ini tial Sr-87/Sr-86, and initial epsilon(Nd) ratios of around -3, suggesting f ormation through crustal contamination of a mantle-derived magma. Metasomat ised granites show higher initial epsilon(Nd) ratios, which can be interpre ted to suggest that the metasomatic fluid was derived from a mantle source. (C) 2000 Elsevier Science B.V. All rights reserved.