Geochemistry of a Proterozoic high silica W-Mo granite from Västra Gråshöjden, central Sweden

Abstract

A geochemical investigation of the Proterozoic Västra Gråshöjden W-Mo bearing granite shows the small granite to consist of several easterly dipping sheets which converge at depth. W and Mo contents range up to 0.5% and 0.27%, respectively. The Mo content increases with depth in the upper two sheets, and correlates with Sn. Bi contents are high in the samples close to the present surface. Cu, Pb, and Zn correlate with each other and two populations emerge, related to Ca content, those samples with a high Ca content having low Fe, Cu, Pb, and Zn. The granite has a high silica, weakly peraluminous character, not distinguishing it from barren granites. Trace elements provide a good discrimination, the granite having high Fe, Pb, Th, and U contents, and generally lower Ba, Zr, and Ti. The REE pattern is characterstic for this and other W-Mo granites, with a concave to horizontal shape and large negative Eu anomaly, being a good tool for geochemical prospecting.

Key Words:

• W
• Mo
• high silica granite
• REE
• geochemistry
• Proterozoic
• Bergslagen
• Sweden