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Clinopyroxene-melt Equilibrium of Cenozoic Basalts in Kuandian, Hannuoba and Mingxi areas, Eastern China and Its Importance
作者姓名:LI Tianfu  and MA Hongwen . Institute of Geology  Chinese Academy of Geological Sciences  Beijing  . School of Materials Science and Engineering  China University of Geosciences  Beijing
作者单位:LI Tianfu1,2 and MA Hongwen2 1. Institute of Geology,Chinese Academy of Geological Sciences,Beijing,100037 2. School of Materials Science and Engineering,China University of Geosciences,Beijing 100083
摘    要:1. Introduction The depth of source of Cenozoic basalts and the genesis of mantle xenoliths in eastern China have been widely discussed by many geoscientists. There were basically two main opinions: one was that the relationship of basalts and the peridotite xenoliths are melt and residues (Cong et al, 1982; Liu et al, 1985; Qiu et al, 1986; E et al, 1987; Chi et al, 1988; Deng et al, 1988), and pyroxenite and gabrro enclaves are accumulation of fractional crystallization (Qiu et al, 1986;…


Clinopyroxene-melt Equilibrium of Cenozoic Basalts in Kuandian, Hannuoba and Mingxi areas, Eastern China and Its Importance
LI Tianfu, and MA Hongwen . Institute of Geology,Chinese Academy of Geological Sciences,Beijing, . School of Materials Science and Engineering,China University of Geosciences,Beijing .Clinopyroxene-melt Equilibrium of Cenozoic Basalts in Kuandian, Hannuoba and Mingxi areas, Eastern China and Its Importance[J].大陆动力学(英文版),2001(1).
Authors:LI Tianfu  and MA Hongwen
Institution:LI Tianfu1,2 and MA Hongwen2 1. Institute of Geology,Chinese Academy of Geological Sciences,Beijing,100037 2. School of Materials Science and Engineering,China University of Geosciences,Beijing 100083
Abstract:Based on clinopyroxene (cpx)-melt equilibrium thermobarometer, this paper deals with the calculation of the clinopyroxene-melt equilibrium temperature and pressure of basalts in Kuandian, Hannuoba and Mingxi areas, eastern China. These basalts all bear mantle xenoliths. The results indicate that the crystallizing temperature and pressure of clinopyroxene phenocrysts in alkaline basalts are commonly higher than those in subalkaline basalts and the crystallizing temperature and pressure of cpx megacrysts are higher than those of phenocrysts, which further confirms that the cpx megacrysts crystallized at higher pressure than cpx porphyritic crystals. The cpx phenocrysts at various pressures indicates that the cpx can crystallize continually along the way the magma moves up. Regression analysis shows, although the basalts bearing mantle xenoliths moved up very rapidly, heat diffusion rather than adiabatic process still occurred. The comparison of temperatures and pressures between the cpx phenocrysts and megacrysts crystallization and xenolith in alkali basalts demonstrates that host magma came deeper than the mantle xenoliths in terms of pressure and the xenoliths are therefore the upper mantle fragments captured by magma along the way up but not the source residues of the host magma as considered previously.
Keywords:basalt  clinopyroxene phenocryst  mantle xenolith  cpx-melt equilibrium  thermobarometer  eastern China
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