中国大陆东部及海域地壳-上地幔结构研究
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摘要
中国大陆东部及海域 ( 98°～ 1 5 0°E,5°～ 5 0°N)位于欧亚大陆和太平洋两大板块的衔接地带 ,且深受来自印度洋板块活动的影响 .本文利用该区域内的 35个数字地震台记录的面波资料 ,采取多重滤波技术等时频分析方法 ,求得了 1 2 5 2条路径上基阶瑞利波的频散曲线 ,然后将研究区域划分为 1°× 1°的网格 ,通过 Occam反演方法求得了 1 0～ 1 5 8s周期范围内基阶瑞利波群速度在研究区域内的分布 .这些速度分布大致反映了不同深度范围介质 S波速度的横向变化情况 .利用求得的纯路径频散 ,进一步反演得到了青藏高原东部—太平洋、南海—蒙古两个剖面的 S波速度随深度的变化 ,发现研究区内的横向不均匀性直到 40 0 km仍很明显 ,各构造单元的划分与速度结构有明显的关系
Eastern China and vicinal sea areas(98°～150°E, 5°～50°N)are located i n the junction zone of Eurasian and Pacific plates, and it is also profoundly in flue nced by the collision between India and Eurasian plates. We utilized surface wa ve data recorded by digital seismic stations in the area, extracted dispersion c urves of fundamental-mode Rayleigh waves along 1 252 paths by means of tim e-frequ ency analysis based on multiple-filter and other techniques. The study area was divided into grids with 1°×1°, group velocity distributions of fundamental R aylei gh waves between 10～158 s were determined by Occam′s inversion. These veloci ty distributions roughly depict the lateral variations of shear wave velocities in different depth ranges. With the determined pure path dispersions we further inv erted for the S wave velocity structures along two profiles from eastern Tibet t o Pacific Ocean and from South China Sea to Mongolia. It is found that the later al heterogeneity is obvious down to 400 km depth, and the velocity structures ar e correlated with tectonic units in the study area.
Eastern China and vicinal sea areas(98°～150°E, 5°～50°N)are located i n the junction zone of Eurasian and Pacific plates, and it is also profoundly in flue nced by the collision between India and Eurasian plates. We utilized surface wa ve data recorded by digital seismic stations in the area, extracted dispersion c urves of fundamental-mode Rayleigh waves along 1 252 paths by means of tim e-frequ ency analysis based on multiple-filter and other techniques. The study area was divided into grids with 1°×1°, group velocity distributions of fundamental R aylei gh waves between 10～158 s were determined by Occam′s inversion. These veloci ty distributions roughly depict the lateral variations of shear wave velocities in different depth ranges. With the determined pure path dispersions we further inv erted for the S wave velocity structures along two profiles from eastern Tibet t o Pacific Ocean and from South China Sea to Mongolia. It is found that the later al heterogeneity is obvious down to 400 km depth, and the velocity structures ar e correlated with tectonic units in the study area.
引文
陈国英,宋仲和,安昌强,等.1991.华北地区三维地壳上地幔结构[J].地球物理学报,34(2):172～181
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徐果明,李光品,王善恩,等.2000.用瑞利面波资料反演中国大陆东部地壳上地幔横波速度的三维构造[J].地球物理学报,43(3):366～376
曾融生,宋子安.1963.我国境内瑞利波的相速度[J].地球物理学报,12(2):148～165
张文佑主编.1986.中国及邻区海陆大地构造[M].北京:科学出版社,305～306
朱介寿,曹家敏,李显贵,等.1997.中国及其邻区地球三维结构初始模型的建立[J].地球物理学报,40(5):627～648
朱良保,许庆,陈晓非.2001.保角变换在区域面波群速度反演中的应用[J].地球物理学报,44(1):64～71
CurtisA,TrampertJ,SniederR.1998.Eurasian fundamental mode surface wave phase velocities and theirrelationshipwith tectonic structures[J].J GeophysRes,103(B11):26919～26947
LebedevS,NoletG,van derHilstR D.1997.The upper mantle beneath thePhilippineSea region from waveforminversions[J].GeophysResLett,24(15):1851～1854
LebedevS,NoletG.2001.The upper mantle beneathSE Asia,II:Structure and evolution[J].J GeophysRes(in press)
RitzwollerM H,LevshinA L.1998.Eurasian surface wave tomography:Group velocities[J].J GeophyRes,103(B3):4839～4878
WierS.1982.Surface wave dispersion andEarth structure in south-easternChina[J].GeophysJ R astrSoc,69:33～47
WU F T,LevshinA L,KozhevnikovV M.1997.Rayleigh wave group velocity tomography ofSiberia,China and thevicinity[J].PureApplGeophys,149:447～473
冯锐,朱介寿,丁韫玉,等.1981.利用地震面波研究中国地壳结构[J].地震学报,3(4):335～350
黄忠贤,郑月军.1998.面波速度的Occam反演[A].见:陈,王水,秦蕴珊,等编.寸丹集庆贺刘光鼎院士工作50周年学术论文集[C].北京:科学出版社,692～704
刘福田,李强,刘建华,等.1989.日本及其毗邻地区的地震层析成像[A].见:《地球物理学报》编委会编.八十年代中国地球物理学进展纪念傅承义教授八十寿辰[C].北京:学术书刊出版社,260～274
马杏垣主编.1989.中国岩石圈动力学地图集[M].北京:中国地图出版社,68
宋仲和,谭承业.1965.用瑞雷和乐夫面波群速度确定我国地壳厚度[J].地球物理学报,14(1):33～44
宋仲和,陈国英,安昌强,等.1993.中国大陆及其海域地壳-上地幔三维速度结构[J].中国科学(B辑),23(2):180～188
孙克忠,冯锐,姚政生,等.1989.西藏—日本剖面的岩石圈构造[J].地震学报,11(2):161～169
徐果明,李光品,王善恩,等.2000.用瑞利面波资料反演中国大陆东部地壳上地幔横波速度的三维构造[J].地球物理学报,43(3):366～376
曾融生,宋子安.1963.我国境内瑞利波的相速度[J].地球物理学报,12(2):148～165
张文佑主编.1986.中国及邻区海陆大地构造[M].北京:科学出版社,305～306
朱介寿,曹家敏,李显贵,等.1997.中国及其邻区地球三维结构初始模型的建立[J].地球物理学报,40(5):627～648
朱良保,许庆,陈晓非.2001.保角变换在区域面波群速度反演中的应用[J].地球物理学报,44(1):64～71
CurtisA,TrampertJ,SniederR.1998.Eurasian fundamental mode surface wave phase velocities and theirrelationshipwith tectonic structures[J].J GeophysRes,103(B11):26919～26947
LebedevS,NoletG,van derHilstR D.1997.The upper mantle beneath thePhilippineSea region from waveforminversions[J].GeophysResLett,24(15):1851～1854
LebedevS,NoletG.2001.The upper mantle beneathSE Asia,II:Structure and evolution[J].J GeophysRes(in press)
RitzwollerM H,LevshinA L.1998.Eurasian surface wave tomography:Group velocities[J].J GeophyRes,103(B3):4839～4878
WierS.1982.Surface wave dispersion andEarth structure in south-easternChina[J].GeophysJ R astrSoc,69:33～47
WU F T,LevshinA L,KozhevnikovV M.1997.Rayleigh wave group velocity tomography ofSiberia,China and thevicinity[J].PureApplGeophys,149:447～473
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