西昆仑山A型花岗岩带的发现及其地球动力学意义

西昆仑山发育一条醒目的Ａ型花岗岩带，空间上与库地幔台展布范围相一致；它形成于印支晚期，与海西晚期Ⅰ型花岗岩共生；岩石相对富碱、ＬＲＥＥ、Ｙ、Ｎｂ、Ｚｒ，贫Ａ１、Ｍｇ、Ｃａ、Ｂａ、Ｓｒ及过渡元素，又以ＳｉＯ２含量范围宽（６６％～７７％）为其显著特色，与澳大利亚东部ＣｈａｅｌｕｎｄｉＡ型花岗岩极为相似。研究表明，花岗岩属Ａ１型，形成于造山晚期相当稳定的拉张环境，是在岩石圈拆沉过程中侵位的。

Discovery of A-type Granite Zone and Its Geodynamic Significance in the Western Kunlun Mts., China

There is a distinct zone of A-type granite in the western Kunlun Mts. with the scope corresponding to the Kudi mantle steps. The A-type granites generated in Late Indosinian, inter-growthing with Late Hercynian I-type granites. The characteristics of A-type granitic rocks are: enrichment in alkali, LREE, Y, Nb, Zr, lean in Al, Mg, Ca, Ba, Sr, transition elements ,and extended SiO2 contents, which are quite similar to those of A-type granite in Chaelundi, Australia. The research results indicate that the studied granites belong to A2-type which formed in late oro-genic extension environment and intruded in the process of the lithospheric delamination.