SHRIMP dating of adakites in western Qinling and their implications.

Abstract

There are a lot of granite from Xiahe to Lixian along the west Qinling which is of the adakite geochemical feature. The paper reports the SHRIMP dating of Yeliguan and Xiahe granite plutons. The SHRIMP ages are 245±6 Ma and 238±4 Ma respectively, belong to early Indosinian period. The adakite is rich of potassium, is classified by high potassium calc-alkalic series. Geology and geochemical data show that the adakite in the western Qinling was formed in the active plate margin, and was associated with the melting of thicken lower crust in the active crust margin. The dating implicated that the convergent and consuming of palaeotethys was processing at early Indosinian.