中国地质2023，Vol.50Issue(6)：1804-1816,13.DOI:10.12029/gc20200709002
西藏中部聂尔错地区辉绿岩锆石U-Pb年龄与地球化学特征:对新特提斯洋板片断离的指示
Zircon U-Pb ages and geochemical characteristics of diabase in Nie'erco area,central Tibet:Implication for Neo-Tethyan slab breakoff
摘要
Abstract
This paper is the result of geological survey engineering. [Objective]Mantle-derived magmatism generally provided an ideal research object to reveal the geodynamic evolution in the depth.The mafic dikes,which shown intensive distribution in Nie'erco area of central Tibet,are regarded as a key aspect to understanding the regional tectono-magmatic evolution.[Methods]In this paper,we report geochronological and geochemical data of the diabases in the Nie'erco area.[Results]The zircon U-Pb dating yielded magmatic crystallization ages of(50.8±0.6)Ma,indicating the Nie'erco diabases emplacement in the early Eocene.The diabase samples have low SiO2,high MgO,Al2O3,TiO2 and total alkali(Na2O+K2O)contents,similar to alkaline ocean island basalt(OIB).These geochemical features suggest that the studied diabases were generated by partial melting of asthenosphere,with the involvement of continental crustal components.[Conclusions]Combined with the post-collisional Linzizong volcanic rocks and OIB-like mafic rocks in southern Tibet,we prefer that the Cenozoic magmatism in Tibet is mainly controlled by the northward subduction of the Neo-Tethyan ocean and the following continent collision between India and Eurasia plates.Our research favor that the Nie'erco diabases were generated in response to the slab breakoff and related upwelling and decompressional melting of sub-slab asthenosphere.关键词
锆石U-Pb年龄/辉绿岩/始新世/新特提斯洋/板片断离/地质调查工程/聂尔错/西藏Key words
zircon U-Pb age/diabase/Eocene/Neo-Tethys/slab breakoff/geological survey engineering/Nie'erco/Tibet分类
天文与地球科学引用本文复制引用
吴浩,徐祖阳,严维兵,郝宇杰,刘海永..西藏中部聂尔错地区辉绿岩锆石U-Pb年龄与地球化学特征:对新特提斯洋板片断离的指示[J].中国地质,2023,50(6):1804-1816,13.基金项目
江苏省基础研究计划(自然科学基金)资助项目(BK20170877)资助. Supported by Natural Science Foundation of Jiangsu Province(No.BK20170877). （自然科学基金）
