Metamorphic rock deformation characteristics, geochemical characteristics and geological significance of the Dakendaba Group in Buhete Mountain on the northern margin of Qaidam Mountain

The Proterozoic Dakendaban Group is the metamorphic crystalline basement of the northern margin tectonic belt and is an important part of the orogenic belt on the northern margin of Qaidam Basin. Previous researchers have made in-depth studies of Dakendaban Group in the areas of Delingha to the west of the Yuka River-Xitieshan-Shaliu River and Da Qaidam, but the study of the east part of the northern Qaidam is relatively insufficient, with the lack of comparative study of the east part and the west part. The authors made meticulous researches on petrology, geochemistry and geochronology of gneiss and amphibolite hornblende schist in Dakendaban Group of Buhete Mountain. Regional correlation shows that the lithologies, mineral assemblage, and metamorphism in the study area are quite similar to things of Dakendaban Group in the west of Delingha Yuka River-Xitieshan-Shaliu River area. Dakendaban Group of Buhete Mountain is mainly a clastic rock intercalated with volcanic rock assemblage, with intense deformation. The environment was a transitional environment of island arc and active continental border, and the magma source experienced crust mantle contamination. Two Sm-Nd isotope samples yielded two groups of isochronal ages, i.e., 2085±14Ma and 2027±19Ma. It is thus concluded that the Dakendaban Group is Paleoproterozoic metamorphic crystalline basement on the northern margin of Qaidam Basin and is an important part of the Paleoproterozoic orogenic belt in northern Qaidam Basin.