Geochronology and geochemistry of Niuwangzhai pluton in east end of North Huaiyang:constraints on deep geological process of Dabie Orogen in Early Cretaceous

Niuwangzhai granite is located in the east end of North Huaiyang in Dabie Orogen. LA-ICP MS zircon U-Pb dating indicates that the Niuwangzhai granite was emplaced at (119.4±1.5) Ma and belongs to the late-stage Early Cretaceous magmatism of Dabie Orogen. The granites are characterized with high SiO₂ (71.98%~77.96%) and high alkali (7.66%~9.30%) contents, low CaO contents (0.19%~0.68%), and high FeO_T/MgO (4.04~39.04, mean value of 12.83) and 10 000×Ga/Al ratios (2.63~2.82). The granites are also enriched in high field strength elements (average content of Zr+Nb+Ce+Y is 294×10^-6) and Rb, but are depleted in Ba and Sr with apparent low δEu values. Geochemical features suggest that the Niuwangzhai granites can be classified into A-type granites. Combined with Sr-Nd isotopic compositions, the granites were probably derived from the gneiss in middle-lower crust of Dabie Orogen. The upwelling of asthenosphere caused by 130 Ma thickened lower crust delamination probably provided heat to melt the intermediate-acid gneiss. The formation of Niuwangzhai granite was possibly associated with extensional tectonic event of eastern China in post 130 Ma.