东天山伊吾地区早石炭世火山岩地球化学特征及其构造意义

Geochemical Characteristics and Its Structural Significance of Early Carboniferous Volcanic Rock in Yiwu Area,Eastern Tianshan

通过对东天山伊吾马依当地区早石炭世火山岩分布、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;火山岩组合主要为一套岛弧相的中基性-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;到了早石炭中-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。

By investigating the early Carboniferous volcanic rock distribution,causation and structural environment relation in Mayidang area,it shows the distribution character of volcanic lithofacies from secondary volcanic facies-explosive phase-effusive facies to volcanic sedimentary facies in this period,the volcanic associations mainly is a series of island arc facies intermediate-intermediate acidic volcanic clastic rock..According to the rock and fossil characters of Tuosibasitao formation,it＇s known that Early Carboniferous in the target area is in the dynamics environment of continental rift transfer into oceanic rift.In the middle and late period of Early Carboniferous,the tectonic movement in the target area,transferred from stretching mechanic into squeezing mechanic,it＇s belong to island arc volcanic rock.So it＇s thought that the Early Carboniferous tectonic evaluation is a ＇open and close＇ movement in the target area.It＇s the first time that the tectonic evaluation mode is carried out,it＇s not only improve the geologic studying degree,but also afford ore-controlling structure information in the target area.