峨眉山玄武岩的辉石研究

本文研究的峨眉山玄武岩的辉石均为单斜辉石。东川碱性火山岩中以透辉石为主,显示碱性岩系辉石的特征,但相对贫 LREE、Ti 等不相容元素,结晶时的 fO₂较高;攀枝花岩带主要是透辉石质普通辉石;其他剖面和地区多为普通辉石,且具拉斑质岩系富钙辉石的成分和演化特点。攀枝花带和西岩区辉石在化学成分上比较原始,而东岩区和中岩区辉石的成分演化程度相对较高。含 Ti 的“其他”阳离子对在各岩区（带）的辉石中均限重要,暗示它们的形成与火山弧环境无关。

A STUDY ON THE PYROXENES IN THE EMEISHAN BASALTS

The pyroxenes in the Emeishan basalts studied are all clinopyroxenes. in the alkalic vol-canics from Dongchuan district diopsides are dominant, which show the characters of alkalic pyroxenes but with relatively low abundances of such incompatible elements as light rare earths and titanium, and were presumably crystallized under higher oxygen fugacities as indicated by their higher propotions of Fe3+. The basalts from the Panzhihua petro-zone are characterized by diopsidic augites. The pyroxenes from the remaining sections and localities investigated are augites, whose chemical compositions show an evolutionary trend characteristic of calcium-rich clinopyroxenes in tholeiitic basalts. As compared with the clinopyroxenes from the Panzhihua petro-zone and western petro-province, those from the eastern and central petro-provinces are more evolved in composition. The "other" cation pairs involving Ti are universally important in the Emeishan basalts, probably implying that their formation has nothing to do with any volcanic arc.