多期岩浆分离结晶作用中微量元素丰度关系

本文提出了多期岩浆分离结晶中元素丰度关系的数学表达式;阐述了微量元素正向演化和反向演化的机理;指出了在不同岩浆分离阶段一些微量元素丰度关系常数(R)有明显变化,可以此作为阶段划分的依据。由峨嵋山玄武岩系及基性-超基性层状岩体研究所得出的元素丰度关系式,适用于其他成分岩浆分离结晶成因的岩浆岩系。本文着重列举数据较齐全的智利安底斯山脉玄武岩、玄武安山岩、安山岩、英安岩和流纹岩岩系的资料作为系统验证。

Relation between Trace Element Abundances in Multistage Magma Fractional Crystallization in Magma Genesis

A mathematic formula for relationship between trace element abundancesin multistage magma fractional crystallization is proposed based on the studyof geochemistry of the Emeishan Basalt and relevant basic-ultrabasic layeredintrusions. This paper discusses the mechanism of normal and inverse evolu-tion of trace elements and the abundance relation constant (R) in therelationship formula. For some elements the constant (R)varies considerablyat different stages of magma fractional crystallization, which gives eyidencesfor the subdivision of these stages. The abundance relation formula couldalso be applied to igneous rocks formed by fractional crystallization ofmagmas with different compositions. There are sufficient data of basalts,basaltic-andesites, andesites, dacites and rhyolites in the Andes, Chile cited asinstance.