Origin of Early Creceouscalc-alkaline granite, Taxkorgan: Implications for evolution of Tethys evolution in central Pamir

Abstract

The Pamir plateau may have been a westward continuation of Tibet plateau. Meanwhile, the Rushan-Pshart suture is correlative to the Bangong-Nujiang suture of Tibet, and the Central Pamir is the lateral equivalent of the Qiangtang Block. We present the first detailed LA-ICPMS zircon U-Pb chronology, major and trace element, and Lu-Hf isotope geochemistry of Taxkorgan two-mica monzogranite to illuminate the Tethys evolution in central Pamir. LA-ICPMS zircon U-Pb dating shows that two-mica monzogranite is emplaced in the Cretaceous (118 Ma). Its geochemical features are similar to S-type granite, with enrichment in LREEs and negative Ba, Sr, Zr and Ti anomalies. All the samples show negative zircon eHf(t) values ranging from −17.0 to −12.5 (mean −14.5), corresponding to crustal Hf model (TDM2) ages of 1906 to 2169 Ma. It is inferred that these granitoids are derived from partial melting of peliticmetasedimentary rocks analogous to the Paleoproterozoic Bulunkuole Group, predominantly with muscovite schists component. Based on the petrological and geochemical data presented above, together with the regional geology, this work provides new insights that Bangong-Nujiang Ocean closed in Early Cretaceous(120–114 Ma).