Petrology, Mineralogy and Geochemistry of the Emeishan Continental Flood Basalts, SW China: Evidence for Activity of Mantle Plumes
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P588.1

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    Abstract:

    Electronic microprobe analyses for olivine, clinopyroxene and Cr-spinel in picrites, which we have discovered recently in the Emeishan continental flood basalt province (ECFBP), show that the olivine is rich in Mg, and that Cr-spinel is rich in Cr. Based on the olivine-melt equilibrium, the primary parental melt compositions are calculated. The high-Mg olivine-hosted picrite can be regarded as parental melt. Thus, the melting temperature and pressure are estimated: T=1600℃ and P=4.5 GPa. It suggests that the picrites are connected with the activity of mantle plumes. Their major element composition is comparable to many other CFBs by their high Fe8, (CaO/Al2O3)8 and low Na8, indicating a high pressure. All rocks display a similar chondrite-normalized REE patterns, i.e., enrichment of LREE, relative depletion of HFSE and absence of negative Nb and Ta but depletion in P and K. Some incompatible element ratios, such as La/Ta, La/ Sm, (La/Nb)PM, (Th/Ta)PM, are in a limited range, show that they were derived

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ZHANG Zhaochong, HAO Yanli, WANG Fusheng, John J. MAHONEYInstitute of Geology, Chinese Academy of Geological Sciences, Beijing, ChinaSchool of Ocean, Earth Science, Technology, University of Hawaii, Honolulu, HI, USA.2004. Petrology, Mineralogy and Geochemistry of the Emeishan Continental Flood Basalts, SW China: Evidence for Activity of Mantle Plumes[J]. Acta Geologica Sinica(),78(1):

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