贵州西部峨嵋山玄武岩中辉石矿物化学及其演化

On the Evolution and Mineral Chemistry of Pyroxen in Emeishan Basalt in West Guizhou

对贵州西部峨嵋山玄武岩中七个单斜辉石作了电子探针分析。确定了单斜辉石的种属,阐述了与岩浆结晶作用及成岩作用相关的辉石的演化趋势。结合全岩化学成份特征,讨论了岩石系列的归属问题,认为本区玄武岩属亚碱性系列与碱性系列的过渡类型,是拗拉槽构造环境的特定产物。

7 electron probe analyses of pyroxenes in Emeishan basalt in west Guizhou show that all of them are Ca-rich clinopyro- xenes.End members occured:Wo=40.77～49.43;En=28.68～42.06;Fs 15.95=21.89,with high titanium content.The general trend of evolu- tion is from rag-rich towards Fe,Ca-rich. Based on the characteristics of mineral assmblage,the chemical composition and evolutional trend of pyroxene and petrochemistry of their host rocks,the writer suggests that the basalts in this area belong to a trausitional type of alkali-series and subalkali-series,and is the product of aulacogen environment.