雅鲁藏布江墨脱段隆升速率:来自黑云母Ar/Ar年代学证据  

Rock Exhumation Rates in Motuo Section of Yarlung Tsangpo River: Evidence from Biotite Ar/Ar Chronology

作　　者：涂继耀[1,2] 季建清 钟大赉[3] 周晶[1] Tu Jiyao;Ji Jianqing;Zhong Dalai;Zhou Jing(Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室,北京100871 [2]中国地震局地球物理研究所,北京100081 [3]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029

出　　处：《地球科学》2021年第12期4533-4545,共13页Earth Science

基　　金：国家自然科学基金项目(Nos.41603055,41490614);中国地震局地球物理研究所基本科研业务费专项(No.DQJB21X26)。

摘　　要：为揭示东喜马拉雅构造结及其周边区域完整地质演化过程,对采集自雅鲁藏布江墨脱段10块基岩样品进行黑云母^(40)Ar/^(39)Ar测年,并利用"Pecube"软件对年龄代表隆升剥露速率进行定量计算.样品黑云母^(40)Ar/^(39)Ar年龄范围为11.25~24.04 Ma,对应隆升剥露速率范围为0.25~0.51 km/Ma.雅鲁藏布江墨脱段地壳隆升剥露速率存在明显南北差异,北段隆升剥露速率高出约0.2 km/Ma.年代学数据及计算结果表明,与东喜马拉雅构造结内部相比,雅鲁藏布江下游墨脱段为地壳隆升剥露活动相对较弱区域.与喜马拉雅地体向拉萨地体俯冲过程相关北西、北西西走向逆断层活动,不仅在东喜马拉雅构造结内部区域发育,在其东侧雅鲁藏布江墨脱段也可能发育.To reveal the tectonic evolution of the eastern Himalayan syntaxis and its surrounding areas,in this paper it reports 10 ^(40)Ar/^(39)Ar ages of biotite from Motuo Section of the Yarlung Tsangpo River.It quantitatively interprets the rock’s uplift and exhumation rates represented by these ages,using a modeling code“Pecube”.Biotite ^(40)Ar/^(39)Ar ages in this paper are in the range of 11.25-24.04 Ma.Corresponding exhumation rates are in the range of 0.25-0.51 km/Ma.The rock exhumation rates in Motuo Section of the Yarlung Tsangpo River have obvious differences between northern and southern,which is characterized by the northern exhumation rates about 0.2 km/Ma higher than the southern.The ages and simulation results show that relative to the inside of the eastern Himalayan syntaxis,the exhumation rates in Motuo Section of the Yarlung Tsangpo River are lower.And the NW/NWW-trending thrust fault zones which were resulted by the collision between Himalayan terrane and Lhasa terrane,not only located in the inside of the eastern Himalayan syntaxis,but also probably located in Motuo Section of the Yarlung Tsangpo River.

关 键 词：东喜马拉雅构造结 雅鲁藏布江 黑云母^(40)Ar/^(39)Ar 隆升剥露 逆断层 地质年代学 

分 类 号：P542[天文地球—构造地质学]