摘要
西昆仑上其汗地区火山岩的时代及归属一直存在争议。利用LA-ICP-MS锆石U-Pb定年法对该区火山岩中霏细岩进行了测年。阴极发光图像显示,锆石发育对称的生长震荡环带结构,Th/U大部分大于0.4,显示岩浆锆石的特征。测得火山岩的^(206)Pb/^(238)U加权平均年龄为(335±4.2)Ma,形成时代为石炭纪,可将其划为阿羌岩组。结合区域地质背景资料,该火山岩可能形成于裂谷环境。
The formation age of the Shangqihan volcanic rocks in West Kunlun has been under controversy for long time.LA-ICP-MS zircon U -Pb dating was used in this article to test the formation age of volcanic rocks. According to cathodeluminescence images of zircons,it have symmetrical oscillatory growth zonal structure.And most of the Th/U is over 0.4,referring to the characteristic of magmatic zircon.The results show zircons yield excellent concordant results with a weighted mean 206 Pb/238 U age of 335 ±4.2 Ma.Therefore,the formation age of the Shangqihan volcanic rocks belongs to Carboniferous period.Furthermore,the Shangqihan volcanic rocks are divided into Aqiangyan Formation.Combining with regional geologic background,we can reasonably conclude that the tectonic setting of the Shangqihan volcanic rocks are referred to rift environment.
出处
《中国地质调查》
2016年第3期21-28,共8页
Geological Survey of China
基金
中国地质调查局"新疆西昆仑1:5万J44E021019等5幅区域地质调查(编号:1212011220635)"
"阿尔金地区1:5万J45E010020等6幅区域地质矿产调查(编号:12120114081901)"项目联合资助
