Timing and origin of Mesozoic magmatism and metallogeny in the Wutai-Hengshan region: Implications for destruction of the North China Craton

摘要

The Wutai-Hengshan region in the northwestern domain of Taihang Mountains (TM) occurs along the Trans-North China Orogen (TNCO) that amalgamates the Western and Eastern Blocks of the North China Craton (NCC). The metamorphic basement in the region is composed of ca. 2.5 Ga granite-greenstone belts within which the Mesozoic magmatic suites are widely emplaced, associated with polymetallic mineralization. The timing, origin and evolution of the magmatic rocks in the Wutai-Hengshan region provide important clues to evaluate the timing, mechanism and process of the destruction of the NCC. In this study, we report new zircon U-Pb and in-situ Hf isotopic data on some of the Mesozoic intrusions associated with Au-Ag-Cu-Mo mineralization from this region. The results show that magmatism and metallogeny in the Yixingzhai and Boqiang-Gengzhuang mining regions occurred during 142-130 Ma, starting with felsic granite porphyry with Mo-Cu mineralization, and intermediate magma associated with gold mineralization. The emplacement of magma and mineralization in Diaoquan mining region occurred about 132-130 Ma, with the intermediate magma emplaced earlier than felsic magma. The in-situ Hf isotopic data indicate that most of the felsic magma was produced by partial melting of the lower crust, and that the intermediate magma witnessed intrusion of mafic magma derived from mantle with magma mixing in different proportion. The process of crystallization differentiation played an important role in the formation of Diaoquan complex intrusion.