Mineralization systems of a mantle plume: A case study from the Emeishan igneous province,southwest China
HU Rui-zhong, TAO Yan, ZHONG Hong, HUANG Zhi-long, ZHANG Zheng-weiKey Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
The theory of mantle plumes casts a new light on explaining intraplate magmatism and mineralization in the dynamics of the Earth. Several important ore deposit types have strong links with the Emeishan igneous province which is thought to be related to a mantle plume. Using the Emeishan as a case study, we discuss the metallogeny of various deposit types and the relationship between the mineralization and magmatism of a mantle plume. Magmatic Cu-Ni-PGE deposits are important ones in the mineralization system of the Emeishan mantle plume. Studies on the geochemistry and mineralization of typical Cu-Ni-PGE deposits, indicate that the ore-bearing intrusions have genetic link with the Emeishan Continental Flood Basalt (ECFB). The parental magma of ore-bearing intrusion is a high-Mg basalt originated from high degree partial melting in center of the mantle plume. The Cu-Ni-PGE deposits are originate within the inner zone of the mantle plume,from which low-Ti basalts are erupted.The paper provides a summary study of geology and geochemistry of the four giant V-Ti magnetite deposits in the Pan-Xi area, and concludes that the parental magma of the deposits originated from the Emeishan mantle plume. The magmas experienced crustal contamination. Furthermore, multiple pulses of magma, magma mixing, double diffusion at the crystallization frontier led to the formation of the rhythmic ores. We also discuss the large-scale native copper mineralization in the border areas between Yunnan and Guizhou Provinces. Geochronological and geochemical evidence indicates that this copper mineralization is associated with magma fractionation during the terminal stage of lava eruptions and the inception of hydrothermal activation. Taking the Huize Pb-Zn deposit as an example, we have studied the genetic relationship between Emeishan basalt and Pb-Zn deposits in terms of ore-forming age, ore-forming material source, ore-forming fluid source and metallogeno-thermal dynamics. The results show that the metallogeny of the Pb-Zn deposits in the district has a close relationship with the emplacement of the ECFB.
【Fund】： 中国科学院知识创新工程重要方向项目(KZCX3 SW 125);; 中国科学院“百人计划”项目
【CateGory Index】： P611
【CateGory Index】： P611