西天山阿吾拉勒地区下二叠统乌郎组火山岩地球化学特征及构造环境

摘要

The Lower Permian Wulang formation from the Awulale in western Tianshan is mainly composed of mafc and felsic volcanic rocks,forming a bimodal volcanic series.Tectonic analysis indicates that the Wulang formation was formed in a post-collisional intracontinental rift.Large amounts of volcanics and volcaniclastic rocks in the Wulang Formation suggest that crustal movement is so frequently in early Middle Permian that some areas suffer crustal strenching and form synsedimentary fauIts.So the rift basin is subjected to the whole process of formation,development and extinction.%西天山阿吾拉勒地区下二叠统乌郎组火山岩为一套陆相火山岩,主要由基性火山岩和酸性火山岩组成,中性火山熔岩较少,表现出双峰式火山岩特征.研究表明,下二叠统乌郎组经碰撞后松弛拉张,伊犁地块拉伸出现陆内火山裂谷环境,该组地层广泛夹持火山岩及火山碎屑岩,表明早中二叠世地壳活动频繁,局部地段地壳拉伸,产生同沉积断层,该断陷盆地经历发生、发展和消亡全过程.