Geological Characteristics And Forecast Of Sulfide Mineralization In Wengen C Area, Inner Mongolia

Wengen C mafic-ultramafic intrusion is located on western section of north edge of Sino-Korea Plateform, which is close to the geosyncline-platform boundary. Mafic-ultramafic intrusion invaded in metaquartzite in Shujigou formation of Zha’ertaishan group. The U-Pb isotopic age is about 280Ma, which belong to early stage of Permian.Main rock types are dunite, wehrlite, troctolite, olivine gabbro, ferrogabbro and gabbro. Petrogenetic minerals are chrysolite （Fo=78.6-85.9）, endiopside, bytownite, anorthite （An=69.0-97.9） and hornblende, and the crystalline sequence is 01 （+Spl）-Cpx （+Sulfide, Opx）-P1-Hbl.The whole rock show high MgO and low SiO₂, K₂O+Na₂O and TiO2. REE characteristics show light REE mid-rich and sharp Eu and Tm positive anomaly （8Eu= 0.76-4.73;δTm=0.89-8.22）. In spider diagram, it is strongly enriched in Pb, Sr and lightly depleted in Nb, Ta, Ti. The composition of primitive magma is estimated to MgO= 11.73%, FeO=11.38%, belonging to high-Mg basaltic magma.Ni sulfide mineralization have been found, and mineral bearing Ni is pentlandite and pyrrhotite within wehrlite and troctolite. The textures of ores are massive, net and disseminated textures. Ore body located in lower part of intrusion as lenticular, stratiform and vein-like,10-40m in thickness and average grade of Ni is 0.1%～0.3%. We think that differentiation of sulfide liquid have been occurred in the processes of mafic-ultramafic magma evolution.At last, the writer summarizes the mechanism for Ni enrichment according to sulfide fractionation behavior and geochemical characteristics. Furthermore, the industrial potential is presented and discussed.