Clinopyroxene-melt Equilibrium of Cenozoic Basalts in Kuandian,Hannuoba and Mingxi areas, Eastern China and Its Importance

• 来源期刊: 大陆动力学（英文版）
• 学科: 地球科学
• 关键词: basalt clinopyroxene phenocryst mantle xenolith cpx-melt equilibrium thermobarometer eastern China
• 年，卷（期）: 2001,（1）
• 页码范围: 13-24
• 页数: 12页
• 分类号: P5
• 语种: 英文

摘要

Based on clinopyroxene (cpx)-melt equilibrium thermobarometer, this paper deals with the calculation of the elinopyroxene-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 megaerysts 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.