Geological Condition of Molybdenum Mineralization, Dongwuqi, Inner Mongolia

Dongwuzhumuqinqi (Dongwuqi for short) of Inner Mongolia is located in the suture line of Sino-Korean plate and Siberian plate (that is Hegenshan deep-seated fault). The tectonic location belongs to southern margin of the Siberian ancient plate and Caledonian-early Variscan geosynclinal fold belt (Huang et al., 2001). The study area is upon the Chagan Aobao-Zhalantun Paleozoic accretive continental margin(I1), which belongs to the DongwuqiZhalantun passive continental margin of volcanic-type (I1) within the southeastern margin of Siberian plate (I) (Shao, 2001). The stratum rarely exposed, the tectonic activity is strong, the magmatic rock exists widely, the magmatic activity is obviously controlled by the structure, the intrusive rocks mainly belong to Yanshanian, and polymetallic ore deposits (points) distribute extensively. The magmatic rock distributes widely in the region, in which mostly is fault in structural development and form. The exposed stratums include Paleozoic Erathem, Mesozoic Erathem and Cenozoic Erathem. The developed intrusive rock of which mainly are acidic rocks, can be divided in to Carboniferous, Late Triassic and Late Jurassic. Regional structure is given priority to with fault, fold is complementary; and the main direction of the fault is northern-east, then northern-west. And the large-scale of the fault is mostly covered by the loose sediment of the Quaternary System, hence it is manifested with lank gully in the direction of north-east and north-west. The developed volcanic structure has seven craters along the Gulapusaihan Aobao-Ximuchang, performing as a string of beads in east-west direction, which indicated that there exists buried fault beneath it in the same direction. The folds mainly exist in Paleozoic Erathem, forming a series of anticlines and synclines. The study area is located in the Chaobuleng-Pear Mountain where boasts polymetallic mineralization, such as iron and zinc, as the polymetallic periphery of Chaobuleng, including iron lead-zinc. The workspace area is Variscan tectonomagmatic belt which developed from the base of the caledonian arc zone, and then came into the western Pacific active continental margin tectonic development stage from the Mesozoic, and developed volcanic plutonic rock of the Mesozoic. According to Inner Mongolia’s 1:1,000,000 aeromagnetic data, the workspace featured in the calm the negative magnetic anomaly, the positive magnetic anomaly in work area and south area may be presumed as the response of Mesozoic concealed rock. Overall characteristics according to Inner Mongolia 1:10 gravity data, of the workspace is a negative anomaly area where is the transition zone of gravity anomaly in north-east and the field value reduced gradually from south to north. Local high and low gravity in-band is oval in axial and mostly from the east to the north. The relatively low anomaly is mainly caused by the Ordovician, Silurian system, and the base of Devonian system. With regard to the area, the Neoproterozoic and Paleozoic carbonate rocks, calcareous siltstone are the iron ore rocks with plentiful polymetallic deposit and the magmatic rocks associated with mineralization are: Baigang granite, granite and biotite granite in Variscan; biotite granite in Yanshanian. These acidic magmas related to mineralization is characterized by rich alkali and the known ore deposit types are contact metasomatic type and hydrothermal type, given priority to contact ZHANG Deyan, XIANG Fang, CHEN Kang, LIU Yao and HAN Xuyuan, 2014. Analysis of the Geological Condition of Molybdenum Mineralization, Dongwuqi, Inner Mongolia. Acta Geologica Sinica (English Edition), 88(supp. 2): 1319-1320.