Crustal Structure and Mantle Transition Zone Thickness beneath the Northeastern Area of the North China Craton and Adjacent Region
详细信息
- 责任者：Wang Bingyu (State Key Laboratory of Lithospheric Evolution ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Chen Ling
- 刊名：Chinese Journal of Geophysics
- 出版年：2013
- 卷期：56(1)
- 关键词：地壳 ; crust ; 地幔 ; mantle ; 莫霍间断面 ; Mohorovicic discontinuity ; 华北地台 ; North China Platform
- 页码：p.60-68
- 图表：illus., 32 refs.
- 分类号：0400
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
We apply a receiver function poststack migration method to teleseismic waveform data received by portable broadband stations,and obtain crustal and mantle transition zone structural image beneath the northeast boundary region of the North China Craton and adjacent areas.The result shows that the crustal thickness of our study region displays significant lateral variations.On the northwestern side of North-South Gravity lineament,the crust is thicker,averaging 38 km in Xingmeng orogenic belt,whereas in Yanshan belt,Songliao Basin and Liaodong anteclise,which locate on the southwestern side of North-South Gravity lineament(NSGL),the thickness of crust is much thinner(30~35 km).This feature probably indicates that the crust of the opposite sides of the NSGL might have been destructed and thinned to different degrees during late Mesozoic to Cenozoic.The structural image of mantle transition zone reveals some topographic lateral variations of the 410 km and 660 km discontinuities.Between longitude 121° and 122°,there are double discontinuities at depths of 660 km and 690 km.East of longitude 122.5°,the 410 km discontinuity depresses 5~20 km,and the 660 km discontinuity uplifts 5~15 km,resulting in a 10~20 km thinner than global average mantle transition zone which reflects a warm lower uppermantle environment.We suggest that the Pacific subducted slabs were trapped in mantle transition zone between longitude 119° and 122° and didn′t reach the west of longitude 118°;With the increasing of slab materials in mantle transition zone,part of the slab might have sunk into the lower mantle to the east of longitude 124°,which would cause a small-scale convection and generate hot upwelling.
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