Early Permian Adakites of the Nora–Sukhotino Terrane in the East of the Central Asian Orogenic Belt: Geochronological (U–Pb, LA-ICP-MS) and Geochemical Data

Abstract

Abstract ––We present results of geochemical and geochronological (U–Pb, LA-ICP-MS) studies of plagiogranites of the Mt. Zmeinaya massif in the Nora–Sukhotino terrane. The studied rocks are of calc-alkaline series and peraluminous type. They formed in collision settings at the final stage of evolution of the Nora–Sukhotino terrane. The high Sr/Y ratios and low Y and Yb contents of the plagiogranites indicate that these are adakitic rocks. The trace element composition of the rocks suggests their high-pressure (>15 kbar) genesis through the melting of metabasites. The youngest zircon population from the plagiogranite has a weighted average concordant age of 295 ± 4 Ma, which corresponds to the early Permian. With regard to the zircon morphology, the obtained age can be considered the age of the plagiogranites.