Geological characteristics and geodynamic background of molybdenum (copper) deposits along Yanshan-Liaoning metallogenic belt on northern margin of North China block
DAI JunZhi~1, MAO JingWen~ 1,2 , YANG FuQuan~1, YE HuiShou~1, ZHAO CaiSheng~1, XIE GuiQing~1 and ZHANG ChangQing~1(1 Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China; 2 Faculty of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China)
The northern margin of the North China craton is one of the most important polymetallic (Mo_Cu_Fe, Pb_Zn, Au, Ag) ore_forming areas in China. The Yanshan_Liaoning molybdenum (copper) metallogenic belt is located in this area and controlled jointly by EW_, NE_ and NNE_trending faults. Mineralization exhibits zoning distribution, with molybdenum deposits in western Liaoning whereas copper (molybdenum) deposits in northern Hebei. These deposits are associated with intermediate_acid granites in time and space. The molybdenum (copper) deposits are usually distributed along the endo_ or exo_contact zone of the granite porphyry, and belong to porphyry, porphyry skarn and skarn types. Sulfur and strontium isotope analyses show that ore_forming materials and ore_forming fluids were derived from the syntectic type granites of the lower continental crust. Molybdenum deposits are associated with Mesozoic Si and K_rich granite porphyry, whereas copper deposits are related to granites with relatively low acid_alkaline contents. Based on metallogenic chronology, the authors hold that there existed two pulses of large_scale mineralization (180 Ma and 140 Ma) in the Yanshan_Liaoning metallogenic belt, whose metallogenic geodynamic settings were the post_collisional orogeny of Northern China block and Siberian block and the late variation stage of the tectonic regime in eastern China, respectively.