新疆伊吾县姜巴斯套组火山岩地球化学特征及构造意义

Geochemical Characteristics and Tectonic Significance of the Volcanic Rocks of the Jiangbasitao Formation,Yiwu County,Xinjiang

通过对新疆伊吾县姜巴斯套组火山岩分布、成因与构造环境关系的调查研究,查明了该时期火山岩相从次火山相-爆发相-喷溢相-火山沉积相的分布特点;火山岩组合主要为-套岛弧相的中基性-中酸性火山碎屑岩、火山熔岩及火山沉积岩。结合该区火山岩地球化学特征及沉积岩特征综合研究认为:研究区早石炭世早期处于大陆裂谷向大洋裂谷转变的动力学环境;到了早石炭晚期(姜巴斯套组沉积时期),研究区构造活动由伸展机制转换为挤压机制,其火山岩表现为岛弧型火山岩系列。因此,认为研究区早石炭世构造演化为一次“开”“合”构造。

Based on the investigation of the distribution,genesis and tectonic environment of volcanic rocks in Jiangbasitao Formation,Yiwu County,Xinjiang,the distribution characteristics of volcanic facies from subvolcanic facies to explosive facies to eruptive facies to volcanic sedimentary facies in this period are identified.The volcanic rock association consists of a set of intermediate-basic and intermediate-acid pyroclastic rocks,volcanic lava and volcanic sedimentary rocks of the island arc facies.Combined study on the geochemical characteristics of volcanic rocks and sedimentary rocks,it is concluded that the study area was in the transition dynamic environment of continental rift to oceanic rift in the early early Carboniferous.In the late early Carboniferous period(sedimentary period of the Jiangbasitao Formation),the tectonic activity in the study area changed from extensional mechanism to compressional mechanism,and the volcanic rocks showed island arc volcanic series.The early Carboniferous in the study area evolved into an"open"and"close"structure.