%0 Journal Article
%T Geochemical and boron isotopic compositions of tourmalines from selected gold-mineralised and barren rocks in SW Finland
%A Matti Talikka
%A Saku Vuori
%J Bulletin of the Geological Society of Finland
%D 2010
%I The Geological Society of Finland
%X Tourmaline-bearing rocks and a number of gold occurrences coexist in southwestern Finland, in a region where extensive magmatism and hydrothermal systems occurred during the Svecofennian orogeny, 1.9¨C1.8 Ga ago. Tourmalines investigated for this study were sampled from late-orogenic granite pegmatites (Er j rvi, Kiety nm ki), quartztourmaline veins from gold occurrences (Kutemaj rvi, Riukka), and the tourmalinised contact between a synorogenic intrusion and supracrustal rocks (Lepom ki Au occurrence, Yl j rvi Cu-W-As-Ag-Au deposit). Major element compositions of the tourmalines are controlled by their host lithologies, whereas their boron isotopic compositions reflect the B reservoir(s) and the magmatic hydrothermal processes of the B-bearing systems. The obtained ¦Ä11B values for granite pegmatite, vein, and intrusion-country rock contact-related tourmalines range between -10.2 ¡ë and -13.2 ¡ë, -10.2 ¡ë and -11.6 ¡ë, and -9.6 ¡ë and -8.7 ¡ë, respectively, and are similar to tourmalines worldwide.The lighter B isotopic composition at Lepom ki gold and Yl j rvi polymetallic occurrences indicate different B reservoirs and magmatic-hydrothermal processes between syn and late-orogenic tourmalines. Geological observations and geochemical data on tourmalinesalso suggest that B was a constituent in hydrothermal fluids at all localities, including the gold-mineralising fluids at Lepom ki, Yl j rvi and Riukka.
%K Tourmaline
%K Chemical composition
%K Boron isotopic composition
%K Gold
%K Finland
%U http://www.geologinenseura.fi/bulletin/Volume82/Talikka_2010.pdf