中国东北地区地幔转换带接收函数三维Kirchhoff偏移成像研究  

Mantle transition zone structure beneath northeast China with receiver function 3-D kirchhoff migration method

作　　者：朱敏 吴庆举[1,3] 宁杰远[2] 张瑞青[1,3] ZHU Min;WU QingJu;NING JieYuan;ZHANG RuiQing(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Institute of Theoretical and Applied Geophysics,Peking University,Beijing 100871,China;Key Laboratory of Seismic Observation and Geophysical Imaging,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]北京大学理论与应用地球物理研究所,北京100871 [3]中国地震局地震观测与地球物理成像重点实验室,北京100081

出　　处：《地球物理学报》2023年第1期197-209,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41874073,41674094)资助.

摘　　要：中国东北地区地幔转换带结构对于研究新生代板内火山深部成因及板片俯冲作用具有重要意义.本文利用东北地区密集流动台阵记录提取到的约60,000接收函数,采用三维Kirchhoff偏移成像方法得到了研究区410-km和660-km界面埋深以及转换带厚度分布图像.成像结果显示:长白山火山下方410-km和660-km界面均出现下沉,且660-km下沉的幅度较410-km更大,在25 km以上,认为与太平洋俯冲板片在转换带的停滞有关.长白山及龙岗火山以西过渡带厚度呈现小幅度减薄的特征,暗示俯冲板片在660 km深度附近可能发生撕裂.板片撕裂引起的热物质上涌和俯冲板片脱水共同为长白山火山提供了深部热源.五大连池火山下方观测到410-km界面抬升,而660-km界面下沉的现象,认为410-km界面的抬升可能与岩石圈拆沉有关,拆沉引起的局部对流可能为五大连池火山提供热源,而660-km界面的下沉可能反映存在残留的太平洋俯冲板片.The structure of Mantle Transition Zone(MTZ)in northeast China is of great significance for studying the deep origins of cenozoic intraplate volcanoes and plate subduction.In this paper,more than 60,000 receiving functions in northeast China are collected,and Receiver Function 3-D Kirchhoff Migration method is used to obtain the topography of the MTZ discontinuities and the MTZ thickness variation in northeast China.Results show that both 410-km and 660-km present depress underneath Changbaishan Volcano,while the depress of 660-km is more obvious,reaching more than 25 km,which may be related to the stagnation of the Pacific subduction plate in the transition zone.The MTZ thickness shows a slight thinning on the west of Changbaishan Volcano and Longgang Volcano,indicating that the subduction plate tears near 660 km.The upwelling of hot material caused by plate tearing and subduction plate dehydration together provide the heat source for Changbaishan Volcano.Below the Wudalianchi volcano,the phenomenon of 410-km uplift while 660-km sinking is observed.Combined with the previous research,we believe that the 410-km uplift is related to the delimitation of the lithosphere,and the local convection caused by the delimitation may be the heat source for Wudalianchi Volcano,while the sinking of the 660-km may be caused by the residual subduction plate.

关 键 词：Kirchhoff偏移成像 接收函数 东北地区 地幔过渡带 

分 类 号：P315[天文地球—地震学]