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Address : Institute of Mineral Resources, Chinese Academy of Geological Sciences, China
Celebration date : 8 Monday September 2008
Author name : Li, jinwen; She, Hongquan; Feng, Chengyou

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  • Article title : Mineralization of gold deposits in Bainaimiao area, inner Mongolia, China
    Article type : Mineral processing
    Location : International Geological Congress,oslo 2008

    Fulltext :

    Bainaimiao, located on the northern margin of North China Plate, is an important gold mineralization area. The gold deposits in this area, occurring in greenschist of the Bainaimiao Formation and the Hercynian igneous rocks, were classified two mineralization types: 1) quartz-vein; 2) quartz-vein and altered host rocks. The orebodies are controlled by faults. The mineralization is in multi-stage and the ore-forming element was enriched tending to the late stage. These show typical characteristics of magmatic hydrothermal deposits. The values of Co/Ni of pyrite in ores were from 1.25 to 2.04; the gold abundance of the Hercynian quartz diorite and plagiogranite varied from 9.06×10-9 to 15.0×10-9; the composition of the lead isotopes from ores and the Hercynian plagiogranite shared similar characteristics. Those data indicated that Hercynian igneous rocks were probably the metallogenic host rocks of the deposits. The values of Δγ(16.65 - 42.51, Δγ=(γsampleMantle)/ γMantle × 1000, γsample=208Pb/204Pb, γMantle=208Pb/204Pb=37.47) and Δβ(11.61 - 30.27, Δβ=(βMantle ×1000, βsample=207Pb/204Pb, βMantle=207Pb/204Pb=15.33) of the lead isotope and δ34S(-4.26—+2.8‰) of the sulfides in ores suggested that the ore-forming substances were related to plutonic magma. According to the isotopes (δDwater-175.04— -108.9‰, δ18ΑOwater-10.98—0.02‰, δ13C -5.695‰) of hydrogen, oxygen and carbon, the ore-forming fluid was originally derived from the magma; and it mixed with meteoric water in its evolution. It is believed that the regional tectonic regime changed from compression to extension in Hercynian period, and the gold mineralization occurred in the extensional dynamical environment in which the ore-controlling structures have undergone multi-extended activities. It’s considered that Au might move as AuCl2- or uH3SiO4 in the ore-forming fluid.