西藏南部新生代东西向伸展作用的深部岩浆作用响应  

Deep Magmatism Response to Cenozoic E-W Extension in the Southern Tibet

作　　者：曾令森[1,2] 高利娥 胡古月[3] 徐倩 田怡红[1] 董汉文 王亚莹 严立龙[1] 赵令浩 李广旭[1] 邸英龙 郝光明[1] 王海涛[6] ZENG Lingsen;GAO Li’e;HU Guyue;XU Qian;TIAN Yihong;DONG Hanwen;WANG Yaying;YAN Lilong;ZHAO Linghao;LI Guangxu;DI Yinglong;HAO Guangming;WANG Haitao(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037;MNR SinoProbe Laboratory,Beijing 100037;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037;Chinese Academy of Geological Sciences,Beijing 100037;National Research Center for Geoanalysis,Chinese Academy of Geological Sciences,Beijing 100037;School of Geographic and Environmental Sciences,Tianjin Normal University,Tianjin 300387)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]自然资源部深地科学与探测技术实验室,北京100037 [3]中国地质科学院矿产资源研究所,北京100037 [4]中国地质科学院,北京100037 [5]中国地质科学院国家地质实验测试中心,北京100037 [6]天津师范大学地理与环境科学学院,天津300387

出　　处：《地球学报》2024年第6期871-881,共11页Acta Geoscientica Sinica

基　　金：国家重点研发计划项目(编号:2021YFC2901901);国家自然科学基金项目(编号:42372070,92055202);第二次青藏高原综合科学考察研究项目(编号:2019QZKK0702);中国地质科学院地质研究所基本科研业务费项目(编号:J2310);中国地质调查局地质调查项目(编号:DD20221817,DD20221630)。

摘　　要：随着新生代喜马拉雅山链的崛起,西藏南部经历了显著的东西向伸展作用,形成一系列近南北向展布的裂谷。伴随着增厚岩石圈的对流减薄或者拆沉,软流圈上涌,藏南岩石圈地幔和中下地壳发生顺次部分熔融作用,形成岩石学和地球化学特征各异的岩浆岩,具体表现为:1)富集岩石圈地幔部分熔融,形成碳酸质、煌斑质和超钾质岩浆岩;2)增厚基性下地壳部分熔融,形成高Sr/Y比值的花岗岩;3)中-下地壳变沉积岩发生白云母脱水/含水部分熔融,形成典型淡色花岗岩。这些新发现限定了藏南裂谷系的启动时限不晚于~30 Ma,为解译世界上造山带和陆内伸展作用过程中大陆岩石圈深部熔融的精细模式提供了典型实例。With the rise of the Himalayan chain during the Cenozoic,southern Tibet experienced significant east–west extension,forming a series of north–south trending rifts.Along with the convective thinning or delamination of the thickened lithosphere,due to asthenospheric upwelling,sequential partial melting of the lithospheric mantle and middle-lower crust induced the formation of magmatic rocks with different petrological and geochemical characteristics.First,the partial melting of the enriched lithospheric mantle resulted in the formation of carbonatites,lamproites,and ultrapotassic rocks.Then,partial melting of the thickened basal lower-crust-derived granites with high Sr/Y ratio.Finally,the middle-and lower-crust metamorphic sedimentary rocks underwent fluid-fluxed or fluid-absent melting of muscovite,forming leucogranites.These new discoveries suggest that the initiation of the north–south trending rifts could have occurred as early as~30 Ma and provide a typical example for interpreting the precise melting patterns of the continental lithosphere in orogenic belts and intracontinental extensional processes worldwide.

关 键 词：硅质碳酸岩 煌斑岩 顺次部分熔融作用 含水熔融作用 伸展作用 藏南 

分 类 号：P534.6[天文地球—古生物学与地层学] P588.11[天文地球—地质学]