Early Cretaceous deformation in the southern Tashkorgan region: Implications for the tectonic evolution of the northeastern Pamir

摘要

The Pamir Plateau comprises a series of crustal fragments that successively accreted to the Eurasian margin preceded the India-Asia collision,is an ideal place to study the Mesozoic tectonics.The authors investigate the southern Tashkorgan area,northeastern Pamir Plateau,where Mesozoic metamorphic and igneous rocks are exposed.New structural and biotite ^(40)Ar-^(39)Ar age data are presented.Two stages of intense deformation in the metamorphic rocks are identified,which are unconformably covered by the Early Cretaceous sediment.Two high-grade metamorphic rocks yielding 128.4±0.8 Ma and 144.5±0.9 Ma ^(40)Ar-^(39)Ar ages indicate that the samples experienced an Early Cretaceous cooling event.Combined with previous studies,it is proposed that the Early Cretaceous tectonic records in the southern Tashkorgan region are associated with Andean-style orogenesis.They are the results of the flat/low-angle subduction of the Neotethyan oceanic lithosphere.