阿尔金山西南段花岗岩类的时空变化与构造作用——来自钾钠含量变化的证据

探讨阿尔金山花岗岩浆作用与构造作用的相互关系有助于全面认识其构造性质和演化特点。系统收集阿尔金山西南段花岗岩类岩石化学数据,统一采用Collins et al.(1982)提出的K2O-Na2O分类图解法,获得各个地史时期花岗岩类的成因类型。五台期均为I型,岩体规模较大,呈近东西向集中成片分布。吕梁期为A型,岩体规模较小,呈北西西向条带状分布于五台期岩体的东北边缘。四堡-晋宁期以S型为主,岩体规模大、分布广、呈北东东向展布。加里东期总体以A型为主,边界断裂带附近I型增多,岩体规模最大、范围最广,总体呈北东东向(北东向)展布。海西期以I型为主,规模小,断续分布于南缘断裂和西北缘断裂的西南端。燕山-喜马拉雅期以A型为主,规模最小,分布零星。五台期至晋宁期岩体主要分布于阿尔金山三条边界断裂所围限的隆起区内,并且在同一时期岩石成因类型具有相对一致性;加里东期隆起区内主体岩石类型与边界断裂带附近及其外侧存在明显差异;海西至喜马拉雅期仅分布于边界断裂带内或东南邻区。上述情况说明,自五台期至喜马拉雅期阿尔金山地区花岗岩类的成因类型、岩体发育规模、展布方向都呈现出有规律的反复交替变化的特点,这是花岗岩浆作用受构造发展演化的不同阶段和不同方向构造作用的交替变化控制的结果。

Tectonic Control for Temporal and Spatial Variation of Granitoids in Southwest Sector of Altyn Mountains--Evidence from Changes of Potassium and Sodium in Granitoids

Studying on relationship between acidic magmatism and tectonism of the Altyn Mountains is helpful to completely recognize the tectonic property and evolutionary characteristics in this area. Collecting the geochemical data of granitic rocks systematically,and based on the method of the K2O-Na2O classification and diagram,which was put forward by Collins et al.(1982),the genetic types of granite can be obtained during different geological periods in the southwest sector of the Altyn Mountains. In the Wutai p...