大兴安岭地幔橄榄岩中熔体的多样性及其成因

摘要

Mantle melt inclusions may sample and record important events of the mantle dynamic evolution. Here we report the electron microprobe analysis of melt inclusions in different mantle minerals of olivine, clinopyroxene and orthopyroxene in the Quaternary volcanic rocks in Daxing' an Mountain Range. Geochemically, these melts can be divided into two groups, low-silicate and high-silicate melts. The low-silicate melts, usually in melt pocket, are results of reactions between basaltic magma and clinopyroxene in the upper mantle. The high-silicate melts in the orthopyroxene reaction rim come from reaction between basaltic magma and orthopyroxene while the rapid ascending of the basaltic magma. The high-silicate melt inclusions produced by mantle metasomatism. Diversity of chemical compositions and occurrences of the mantle melts reveal their different origin, and also provide evidences of the mantle dynamic evolution.%本文报道了大兴安岭第四纪火山岩中的地幔橄榄岩中橄榄石、单斜辉石和斜方辉石颗粒内部熔体产状(囊体、包裹体和反应边)和成分(低硅熔体和高硅熔体)的多样性,初步讨论了不同熔体的成因.低硅熔体囊体是在地幔深部玄武岩浆与橄榄岩中单斜辉石发生交代反应的产物,斜方辉石反应边的高硅熔体是橄榄岩被捕获上升过程中玄武岩浆与斜方辉石反应的产物,高硅熔体包裹体是地幔中存在的交代熔体.