地质科技情报2018，Vol.37Issue(1)：96-107,12.DOI:10.19509/j.cnki.dzkq.2018.0113
新疆东天山博格达造山带西段基性侵入岩的U-Pb年代学、地球化学及其构造意义
U-Pb Dating,Geochemical and Tectonic Signficances of Basic Intrusive Rocks from the West of Bogda Orogenic Belt, Eastern Xinjiang
摘要
Abstract
The Bogda orogenic belt is widely distributed with basic intrusive rock mass,and its origin is of great significance to correctly understand the geodynamic background of the area.This paper studies systematically petrology,geochemistry and zircon U-Pb geochronology of basic intrusive rocks in the west of Bogda orogenic belt in order to define its petrogenesis and tectonic significance,and then to provide a basis for solving geological tectonic evolution of the belt.Rock geochemical analyses show that its SiO2 ranges from48.08％ to 50.88％,and ALK from 3.09％ to 4.39％(less than 5％),rich in CaO(6.87％-11.41 ％00),and depleted in Al2O3(12.59％-18.49％).It has MgO ranging from 3.78％ to 7.66％,and Mg# =31.75-65.73(the average is 51.29),A/CNK =0.60-0.80,indicating that it belongs to metaluminous middle K calc-alkaline rock series.The analysis also shows that the belt has low REE(36.30× 10-6-101.41× 10-6),between light and heavy rare earth and heavy rare earth internal no obvious fractionation process.Obvious loss of Th,Ta and Nb element,no obvious loss of Ti and slight enrichment in U element,show the characteristics of continental rift magmatism.The relevant diagram and the ratio about the trace elements and rare earth elements,indicate that the basic intrusive rock magma originates from the loss lithospheric mantle,suffering contamination of the crust,with low differentiation evolution degree,as the original phase spinel peridotite higher degree of partial melting,formed in the intraplate rift environment.Moreover,gabbro LA-ICP-MS zircon U-Pb dating results show that the forming age of (305.0± 1.6)Ma (Latest Carboniferous),in the late period of the Bogda rift volcano activity,indicates the west of Bogda rift underwent a conversion from the overall extension stage to the confined extension stage.The analysed of regional geological datas claim that there is a large rift evolution related to magmatism and during Late Paleozoic Era (Early Carboniferous-Early Permian),the orogenic belt developed on the basis of rifting.Propably,its formation is related to the oblique subduction of the Paleo-Asian Ocean plate towards the Junggar-Turpan-Kumul plates along the Kalameili subduction belt.关键词
博格达造山带/基性侵入岩/地球化学/LA-ICP-MS锆石U-Pb定年/大陆裂谷/古亚洲洋Key words
Bogda orogenic belt/basic intrusive rock/geochemistry/zircon LA-ICP-MS U-Pb dating/continental rift/Paleo-Asian Ocean分类
天文与地球科学引用本文复制引用
李江涛,侯可军,何学锋,杨鹏涛,刘亮,梁斌,苏画,杨宇东,陈围,江辉..新疆东天山博格达造山带西段基性侵入岩的U-Pb年代学、地球化学及其构造意义[J].地质科技情报,2018,37(1):96-107,12.基金项目
国家自然科学基金项目(41472310) （41472310）
新疆维吾尔自治区地质勘查基金项目“新疆东天山甘河子一带1∶5万区域地质矿产调查”(A14-1-LQ03) （A14-1-LQ03）
