利用接收函数方法研究青藏高原东南部地壳结构  

Crustal Structure of SE Tibet Plateau by Receiver Function

作　　者：曹旭 米宁[1] 于大勇[1] 王良书[1] 徐鸣洁[1] 李华[1] 黄周传[1] 王攀 CAO Xu;MI Ning;YU Dayong;WANG Liangshu;XU Mingjie;LI Hua;HUANG Zhouchuan;WANG Pan(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2018年第5期715-722,共8页Geological Journal of China Universities

基　　金：自然科学基金项目(41674049)资助

摘　　要：青藏高原东南部作为板块碰撞的前缘地带一直是地球科学研究的热点,为了揭示碰撞前缘地带地壳结构特征,作者利用布设在中国青藏高原东南部的38个宽频带流动台站记录的2487条远震P波接收函数,采用接收函数CCP叠加(共转换点叠加)和H-κ叠加两种方法获得了研究区域详细的地壳厚度图像和泊松比值。研究结果显示:两种方法获得的地壳厚度特征具有较好的一致性;青藏高原东南部地壳厚度存在明显的东西差异和南北差异;喜马拉雅构造区内莫霍面深度变化较大,介于65～80 km之间;拉萨地体内莫霍面深度介于72～80 km之间;雅鲁藏布缝合带两侧地壳厚度突变,缝合带北侧和南侧地壳厚度相差约8 km。研究区域平均泊松比值较小,为0.24,和大多数造山带泊松比偏低的特征类似。研究区域中下地壳广泛存在强转换界面,该界面可能对应中下地壳高速层的上界面,埋深40～70 km,表明壳内发生深熔或部分熔融作用,导致壳内发生重力分异,在中下地壳形成了高速薄层。As the front region of plate collision,the southern Tibet has always been the hotspot in geoscience research.To reveal the features of the crustal structure of collision frontal zone,we used 2487 tele-seismic records recorded by 38 broadband stations in the southeast Tibet.Then we calculated the crustal thickness and Poisson’s ratio of this area by CCP stacking and H-κstacking.The results of the crustal thickness obtained by the two methods are in good agreement,and the crustal thickness in the southeastern Tibet has obvious difference in east-west and north-south.The depth of Moho varies greatly in the Himalaya tectonic zone,ranging from 65 to 80 km.The depth of Moho in Lhasa block ranges from 72 km to 80 km.The crustal thickness on both sides of the Yarlung Zangbo suture has been abruptly changed.The difference in thickness between the north side and the south side of the suture is about 8 km.The average Poisson ratio in the study area is 0.24,which is consistent with the feather that the Poisson ratio in most orogenic belts is low.A strong transition interface exists widely in the middle and lower crust of the study area,the interface may be the upper interface of the high-velocity layer in the middle-lower crust,with a depth of 40-70 km.It indicated that deep melting or partial melting occurred in the crust,leading to gravitational differentiation and forming a highvelocity thin layer in the middle-lower crust.

关 键 词：青藏高原东南部 接收函数 H-κ叠加 CCP叠加 地壳结构 

分 类 号：P541[天文地球—构造地质学] P631.4[天文地球—地质学]