Spatial-temporal distribution and tectonic setting of Mesozoic W-mineralized granitoids in the Xing-Meng Orogenic Belt, NE China

Abstract

The Xing-Meng Orogenic Belt is characterized by intense and widespread Mesozoic granitic magmatism related to large-scale W mineralization. Three periods of W-mineralized granitic magmatism can be distinguished: Early Triassic, Early–Middle Jurassic, and Late Jurassic–Early Cretaceous. Early Mesozoic W-mineralized granitoids are I-type granites with metaluminous to weakly peraluminous characteristics, with higher Rb concentrations and lower K/Rb ratios than coeval W-barren granitoids. Late Mesozoic W-mineralized granitoids belong to highly fractionated A-type granites, enriched in Rb, Th, and U, and depleted in Ba, Sr, P, Ti, and Eu. They have higher Rb/Sr and U/Th ratios, and lower (La/Yb)N, LREE/HREE, Eu/Eu*, K/Rb, Zr/Hf, Nb/Ta, and Y/Ho ratios than contemporary W-barren granitoids. Mesozoic W-mineralized granitoids mainly originated from the partial melting of juvenile lower crust, whereas Early Mesozoic W-mineralized granitoids encompassed minor reworked ancient crustal material. Triassic W-mineralized granitoids formed in a syn- and/or post-collision setting related to the closure of Paleo-Asian Ocean. Early–Middle Jurassic W-mineralized granitoids formed in a compressional setting created by the subduction of Paleo-Pacific Ocean plate in the east and the closure of Mongol-Okhotsk Ocean in the west. Late Mesozoic W-mineralized granitoids formed in a post-orogenic extensional setting controlled by the MOO and PPO tectonic regimes.