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摘要
The Yixingzhai and Xinzhuang gold deposits are the most important gold mineralization of the WutaiHengshan region in the center of the North China Craton (NCC). Here we present new geological, mineralogical, geochemical and geochronological evidence from these deposits with a view to formulate a comprehensive model for the Mesozoic magmatism and metallogeny in the NCC. Our Re-Os dating of molybdenite from the Hewan granite porphyry constrains the timing of mineralization as 142 Ma. Gold mineralization occurred in the late stage of magmatism with close temporal and spatial relationships with the Sunzhuang pluton. Intensive parameters using amphibole, biotite, magnetite-ilmenite mineral thermobarometry and oxygen fugacity indicate that the parental magma for the Sunzhuang pluton evolved at high oxygen fugacity (>NNO + 2 buffer), and was emplaced at a depth of 2-2.6 km. The He-Ar isotopic composition of the fluid inclusions from pyrite grains in the Yixingzhai gold deposit suggests the involvement of mantle-derived fluids although the Pb isotope data shows that ancient lower crust is the major source. The major and trace element features, Sr-Nd-Pb and zircon Hf isotope data coupled with available geophysical information suggest that magmatism and mineralization in this region witnessed the interaction of mantle-derived mafic magmas with lower crust, with the latter as the major source. The magmatic and metallogenic processes involved the following: (1) partial melting and production of mafic magma triggered by upwelling asthenosphere; (2) mafic magma underplating under lower crust and partial melting of the ancient lower crust generated granitic magma; (3) formation of intermediate magma through the interaction between mafic and felsic magmas; (4) separation of ore-forming fluids from the Sunzhuang pluton and their migration through fault zones in the shallow crust generating the gold mineralization.
- 出版日期2017-8
- 单位中国地质大学（北京）
