【摘要】 埃达克岩是一套钙碱系列岩浆岩,其主要地球化学特征为SiO₂≥56％,Al₂O₃≥15％,MgO通常小于3％,低重稀土元素和Y(Y≤18×10^-6,Yb≤1.9×10^-6),高Sr(多数大于400×10^-6),无Eu异常或有轻微的负Eu异常, 其成因主要有两类,一种为由俯冲板片的熔融形成,另一种由底侵玄武质下地壳熔融形成,埃达克岩具有重要的成矿意义。更多还原

【Abstract】 Adakite was proposed over a decade ago. It is a kind of acid-intermediate and calc-alkaline igneous rock, with the stickup characteristics of SiO2≥56%, A12O3≥ 15%, relatively depletive HREE and Y(Y≤18 × 10-6, Yb≤ 1. 9 × 10-6), high ST(> 400 × 10-6), La/Yb and Sr/Y, as well as positive Sr anomaly but absent or slightly negative Eu anomaly. There are two types of adakites with different petrogenesis: one is formed by the melting of subducting young(≤S25 -30 Ma) slab, and the other is formed by the partially melting of basaltic lower crust under the continental accretion setting. Adakites are important indicators of ore deposits.更多还原