Partial melting of amphibolite lower crust: A potential magma source for granite-related W mineralization

Abstract

Magmas for the granite-related tungsten deposits (GTD) are commonly considered to be generated from the upper to middle crustal metasedimentary protoliths, and these magma source materials have previously been regarded as the determinant factor to the granite-related tungsten mineralization. Here we demonstrate, based on high Sr/Y and (La/Yb)N granites related to wolframite mineralization from the Jiaoxi, Jiaodong and Anglonggangri wolframite mining districts in the northern Lhasa terrane, Xizang that this viewpoint is not necessarily correct. Petrological and geochemical evidences suggest that the wolframite mineralization related granites in these mining areas were sourced from partial melting of the K-rich amphibolite lower crust of the Lhasa terrane and underwent significant fractional crystallization. These results indicate that the amphibolite lower crust can also be a candidate magma source for the GTD and the high evolution processes of granite is more important than the nature of the source materials during tungsten mineralization.