Molybdenum Metallogenic Geological Background And The Prospecting Direction From The Cao Siyao In Xinghe County, Inner Mongolia

The studied molybdenum ore is located at the north edge of Huabei Platform, east ofLiangcheng Fault-uplift of Inner Mongolia Platform Uprise. The exploration area is on themiddle section of Datong-Shangyi NE structure tectonicmagmatic belts, located at thesouthwest side of the intersection of Datong-Shangyi NE structure tectonicmagmatic belts,Daihai-Huangqihai NE fault, Shangdu-Weixian NW structure tectonicmagmatic belts andHohhot-Jining-Chicheng nearly WE trending deep fault. From regional geology analysis, athree phase folding can be identified; fault structure development is common and the regionalstratum distribution is obviously controlled by regional NE, NW trending fault. Magmaticactivity at the intersectional area is intensive, which benefits the mineralization process ofhydrothermal ore deposit. The degree of mineralization relates to the formation of tectonicfissure before or during the mineralization process–higher developed fissure causes morematured mineralization. Due to intensive regional magmatic activity, both early Cretaceousmany porphyry granite-porphyry(K11γπ) and less porphyry granite-porphyry(K21γπ) havevery limited exposure area, but closely related to molybdenum ore mineralization in thestudied area. The molybdenum ore include a bigger ore body and three smaller ore bodies,which are all been concealed. The ore bodies are generally consisting of leptite and granulite(of Huangtuyao Formation, Jining Group with molybdenite stringer), and Mesozoic diabase,granite-porphyry and fault cataclastic rock. The ore deposit is controlled by south rim ofCaosiyao fault. The ore deposit has a simple shape and the ore grade decreases orderly fromthe center to the edge. Surrounding rock mainly consists of leptite and granulite (ofHuangtuyao Formation, Jining Group) and contents a small amount of diabase,granite-porphyry and fault cataclastic rock. The mineralization grade of leptite, granulite,diabase, granite-porphyry and fault cataclastic rock is0.11%,0.098%,0.103%,0.083%and0.066%, respectively. The largest fault in this area is fault F1located at the west side ofMolybdenum ore deposit, controlling the west edge of the deposit. This fault has thecharacteristic of polyphasic activities and controls the polyphasic intrusive complex in thisarea. The extraction of large amount of metallogenic material by multi-stage magmaticactivities provided a material basis for the formation of Molybdenum ore deposit. The fault inthis area is rock-control and ore-control structure. The diabase and visible multi-phasesgranite porphyry on surface developed in this area is formed before molybdenum oremineralization and mineralized later with surrounding rock as part of the molybdenum oredeposit, showing no subversive effect to the ore. The ore deposit is shaped like an upsidedown bowl, very similar to brachyaxis isochoric anticline. The studied molybdenum ore mainly consists of molybdenite and pyrite, followed by wolframite, galena, marmatite,magnetite, ilmenite, copper pyrites and pyrrhotite.