地质通报2017，Vol.36Issue(10)：1772-1782,11.
西藏洞错埃达克质火山岩LA-ICP-MS锆石U-Pb年龄及其构造意义
LA-ICP-MS zircon U-Pb ages of adakitic rocks in Dongco area, Tibet, and their tectonic implications
摘要
Abstract
The Ban'gong Co-Nujiang suture zone is one of the main suture zones in the Tibetan Plateau. Its closure time has been controversial, which causes some restrictions to the study of the evolution of the Tibetan Plateau. This paper deals with the discov-ered trachyandesite which occurs in Bangong Co-Nujiang suture zone. LA-ICP-MS zircon U-Pb analyses suggest that the trachy-andesite was formed at 102±1.9Ma, and that the volcanic rocks were formed in late Early Cretaceous. They are characterized by ada-kite-like rock:high Na content, SiO2, Al2O3, Mg# and high Sr/Y values(25.2~42.2), and low Nb(11.1×10-6~16.6×10-6), Y(11.7× 10-6~18.3×10-6)and Yb(1.06×10-6~1.77×10-6)values. The differentiation between HREE and LREE is obvious. The authors hold that high Mg# adakite-like rock(Mg#=(50.0~54.1)resulted from the reaction between the rising melt of remnant oceanic crust and the mantle wedge. Therefore, the origin of Dongcuo adakitic-like rocks may be related to the collision between Lasha and Qiang-tang blocks after the closure of the Bangong Co-Nujiang Ocean. Based on these data, the authors consider that Bangong Co-Nuji-ang Ocean had been closed before 102Ma.关键词
西藏洞错/班公湖-怒江特提斯洋/粗安岩/埃达克质岩/LA-ICP-MS锆石U-Pb年龄/残余洋壳熔融Key words
Dongco area/Bangong Co-Nujiang Ocean/trachyandesite/adakitic rock/LA-ICP-MS zircon U-Pb ages/remnant oceanic crust分类
天文与地球科学引用本文复制引用
闫国川,王保弟,刘函,王立全,周放..西藏洞错埃达克质火山岩LA-ICP-MS锆石U-Pb年龄及其构造意义[J].地质通报,2017,36(10):1772-1782,11.基金项目
中国地质调查局项目《西南三江有色金属资源基地调查》(编号:DD20160016)和国家自然科学基金项目《羌塘中部泥盆纪—石炭纪岩浆作用对古特提斯洋构造演化的制约》(批准号:41773026)、《藏南仲巴地区始新世花岗质岩石成因及其对拉萨地壳加厚的启示》(批准号:41603038) （编号:DD20160016）
