The Microcosmic Traces of Mantle Fluid and the Implications forLiquation Metallogenesis from Ultrabasicbasic Xenoliths inEmeishan Basalt, Zhongdian, Yunnan

Abstract

Abstract:

Based on the research of mineralogy and petrology using EMPA, SEM and Energy Spectra, we found a kind of Black Opaque Material (BOM) which is composed of microcrystalline silicate and spinel group mine rals from ultrabasic basic xenoliths in Emeishan Basalt. From the crystal chemistry and element geochemistry of these microcrystalline minerals, we draw that they are the products and relics of mantle fluid which is not immixed with the host magma (e.g.basalt magma). During the evolution of the mantle fluid, differentiation by liquation is expressed as silicate→spinel→magnetite→chromite→ilmenite. The mantle fluid can also lead to the alternation and mineralization for host rocks and xenoliths, composing to be an important dynamic and substance source, while the mantle plume in western Yunnan is favorable to the endogenous metal mineralization after Permian.

Key words: Emeishan Basalt, ultrabasicbasic xenolith, microcosmic trace of mantle fluid, magma and fluid liquation metallogenesis, Zhongdian, Yunnan

YI Li-Wen, LIU Xian-Fan, DENG Jiang-Gong, LIN Ke-Fa, TU Shao-Xiong, DIAO Fu-Feng, LI Chun-Hui, HUANG Yu-Peng, DONG Yi, JU Jin-Xi. The Microcosmic Traces of Mantle Fluid and the Implications forLiquation Metallogenesis from Ultrabasicbasic Xenoliths inEmeishan Basalt, Zhongdian, Yunnan[J]. Geoscience, 2012, 26(3): 421-432.

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