Isotope systematics of ore-bearing granites and host rocks of the Orlovka-Spokoinoe mining district, eastern Transbaikalia, Russia

Abstract

Pb, Rb and Sr isotope data are reported for the Khangilay, Orlovka and Spokoinoe granite massifs and their host rocks in the Orlovka-Spokoinoe mining district, Eastern Transbaikalia, Russia. Pb isotope analyses indicate a common Pb source for all three granite massifs reflecting a homogenous source melt from which all magmatic members evolved. Pb isotope systematics identify two possible scenarios for the source of Li-F granites: 1) a crust-mantle source where a mixture of MORB and continental-derived material were brought together in an orogenic environment; and 2) a type II enriched mantle source where subducted continental material could have been strongly implicated in volcanic suites. New Rb-Sr isotope age data yield a 143.8 +/- 4.2 Ma age for barren granites of the Orlovka and Khangilay massifs.