川西连龙含锡花岗岩的时代与形成构造环境

The Age and Tectonic Setting of Lianlong Sn-bearing Granite in Western Sichuan Province

通过岩石地球化学和Rb Sr同位素研究 ,发现川西连龙花岗岩是富含Sn、Ag多种成矿元素的高K钙碱性岩体 ,地球化学上显示出A型花岗岩特点。 4个全岩样品给出的Rb Sr等时线年龄为 87± 1Ma,相关系数R =0 .9988,Isr=0 .70 95。结合构造环境分析 ,查明该岩体是燕山运动晚期 ,在弧陆碰撞造山之后陆内伸展阶段 ,主要由地壳富泥质岩石部分熔融形成。

Based on petro geochemical and Rb Sr isotopic studies, this paper points out that Lianlong granite in western Sichuan Province is a Sn Ag rich high K calc alkaline granite, and geochemically shows characteristics of A type granite. Four bulk rock samples give the isochronic age of 87±1 Ma, the correlation coefficient R =0.9988, and the I Sr 0.7095. Combined with an analysis of its tectonic setting, it is held that the granite was formed mainly from partial melting of crustal mud rich rocks during intraplate extension in the post orogenic stage after the collission orogenics of Yidun island arc in late Yanshanian period.