青藏高原东北缘地壳上地幔速度结构的地震层析成像研究
|
摘要
本文收集了甘肃、青海、宁夏、陕西和四川台网的130个台站1980-2002年间记录的3 229个区域地震(MS≥1.5)和168个远震资料,从55 024个区域地震震相中挑选出了51 210个最大走时残差为3.0s的震相,选取了2 651个远震震相。层析成像结果显示:(1)青藏高原东北缘地区下地壳存在大范围的P波速度低速异常,上地幔顶部多数地区平均P波速度为8.05km/s左右,接近于大陆下方全球的Pn波平均速度8.1km/s,使得莫霍间断面比较清晰,莫霍面反射波能量较强;(2)研究区内发生大震的震中大多位于深度图中10km的低速区、30km的高速区附近和50km的低速区附近,表明这些区带为孕震区;(3)青藏高原东北缘地区的主要断裂带均是逆冲兼走滑断裂,多数位于速度正负异常的过渡区上,且很可能是超壳断裂;(4)从张掖经海原、平凉再向南拐的弧形地带可能就是青藏高原的边缘地带;且预示着阿拉善地块有地台活化的迹象;(5)从层析成像结果中切出的二维速度扰动剖面与人工地震测深剖面吻合较好。
The seismic data including 3 229 local earthquakes(MS≥1.5) and 168 teleseismic events occurred during 1980 to 2002 recorded by 130 seismic stations in the seismic networks of Gansu,Qinghai,Ningxia and Sichuan province are collected,and from 55 024 local phases we selecte 51 210 with the maximum travel time residual of 3.0 s,and 2 651 teleseismic phases.The tomographic inversion results show that:(1) Lower P-wave velocity anomaly exists widely in the lower crust beneath the northeastern margin of the Qinghai-Tibet plateau.Average P-wave velocity in most of the top of upper mantle is 8.05 km/s that is close to the global continental average Pn-wave velocity with 8.1 km/s.It indicates the existence of a clear Moho interface and strong reflections from Moho interface.(2) The epicenters of most strong earthquakes occurred in the research region are located in the lower velocity areas in the 10 km depth range,around the higher velocity areas in the 30 km depth range and lower velocity areas in the 50 km depth range,which suggests that these areas could be the possible earthquake pregnancy regions.(3) Major fault belts in the region are reverse thrust with strike slip,locate on the transition zones between lower and higher velocity anomalies,and are possibly ultra-crustal faults.(4) The arc belt from Zhangye to Haiyuan and Pingliang and turns to south is possibly the marginal belt of Qinghai-Tibetan plateau,and indicates the platform activation in Alashan platform.(5) The 2D velocity perturbation profile taken from the seismic tomographic results shows fairly agreement with deep seismic sounding profile.
The seismic data including 3 229 local earthquakes(MS≥1.5) and 168 teleseismic events occurred during 1980 to 2002 recorded by 130 seismic stations in the seismic networks of Gansu,Qinghai,Ningxia and Sichuan province are collected,and from 55 024 local phases we selecte 51 210 with the maximum travel time residual of 3.0 s,and 2 651 teleseismic phases.The tomographic inversion results show that:(1) Lower P-wave velocity anomaly exists widely in the lower crust beneath the northeastern margin of the Qinghai-Tibet plateau.Average P-wave velocity in most of the top of upper mantle is 8.05 km/s that is close to the global continental average Pn-wave velocity with 8.1 km/s.It indicates the existence of a clear Moho interface and strong reflections from Moho interface.(2) The epicenters of most strong earthquakes occurred in the research region are located in the lower velocity areas in the 10 km depth range,around the higher velocity areas in the 30 km depth range and lower velocity areas in the 50 km depth range,which suggests that these areas could be the possible earthquake pregnancy regions.(3) Major fault belts in the region are reverse thrust with strike slip,locate on the transition zones between lower and higher velocity anomalies,and are possibly ultra-crustal faults.(4) The arc belt from Zhangye to Haiyuan and Pingliang and turns to south is possibly the marginal belt of Qinghai-Tibetan plateau,and indicates the platform activation in Alashan platform.(5) The 2D velocity perturbation profile taken from the seismic tomographic results shows fairly agreement with deep seismic sounding profile.
引文
①地质矿产部第二综合物理勘探大队.青海花石峡—四川简阳爆破地震测深成果报告.1991.
[1]曾融生,滕吉文,阚荣举,等.我国西北地区地壳中的高速夹层[J].地球物理学报,1965,14(2):94-106.
[2]林中洋,蔡文伯,陈学波,等主编.青海门源至福建宁德地学断面[M].北京:地震出版社,1992.
[3]王椿镛,林中洋,陈学波.青海门源-福建宁德地学断面综合地球物理研究[J].地球物理学报,1995,38(5):590-598.
[4]孙武城,徐杰,杨主恩,等主编.上海奉贤至内蒙古阿拉善左旗地学断面[M].北京:地震出版社,1992.
[5]闵祥仪,周民都,郭建康,等.灵台-阿木去乎剖面地壳速度结构[J].西北地震学报,1991,13(增刊):29-36.
[6]李清河,郭建康,周民都,等.成县-西吉剖面地壳速度结构[J].西北地震学报,1991,13(增刊):37-43.
[7]李松林,张先康,张成科,等.玛沁—兰州—靖边地震测深剖面速度结构的初步研究[J].地球物理学报,2002,45(2):210-217.
[8]周民都,吕太乙,张元生,等.青藏高原东北缘地质构造背景及地壳结构研究[J].地震学报,2000,22(6):645-653.
[9]刘建华,刘福田,吴华,等.中国南北带地壳和上地幔的三维速度结构[J].地球物理学报,1989,32(2):143-151.
[10]李清河,郭守年,吕德徽.鄂尔多斯西缘与西南缘深部结构与构造[M].北京:地震出版社,1999.
[11]任纪舜,姜春发,张正坤,等.中国大陆构造及其演化[M].北京:科学出版社,1981.
[12]国家地震局“鄂尔多斯周缘活动断裂系”课题组.鄂尔多斯周缘活动断裂系[M].北京:地震出版社,1988.
[13]王萍,王增光.阿拉善活动地块的划分及归宿[J].地震,1997,17(1):103-112.
[14]李玉龙,邢成起.河西走廊地质构造基本特征以及榆木山北麓与黑河口上龙王活断层研究[J].西北地震学报,1988,10(2):35-47.
[15]王清晨,孙枢,李继亮,等.秦岭的大地构造演化[J].地质科学,1989,(2):129-142.
[16]刘树根,罗志立,戴苏兰,等.龙门山冲断带的隆升和川西前陆盆地沉降[J].地质学报,1995,69(3):205-214.
[17]Aki K,Lee W H K.Determination of three dimensional ve-locity anomalies under a seismic array using first P arrival times from local earthquakes1.A homogeneous initial model[J].J.Geophys.Res.,1976,81:4381-4399.
[18]Zhao D,Horiuchi S,Takagi A.3-D seismic velocity struc-ture of the crust and the uppermost mantle in the northeast-ern Japan arc[J].Tectonopgysics,1990,181:135-149.
[19]Zhao D.A tomographic study of seismic velocity structure in the Japan Islands[D].Tohoku University,1991.
[20]Zhao D,Hasegawa A,Horiuchi S.Tomographic imaging of P and S wave velocity structure beneath northeastern Japan[J].Journal of Geophysical Research,1992,97(B13):19909-19928.
[21]Zhao D,Hasegawa A.P wave tomographic imaging of the crust and upper mantle beneath the Japan Islands[J].Jour-nal of Geophysical Research,1993,98(B3):4333-4353.
[22]Zhao D.Deep structure of Japan subduction zone as derived from local,regional,and teleseismic events[J].Journal of Geophysical Research,1994,99(B11):22313-22329.
[23]丁志峰.近震层析成像的理论与应用[D].北京:中国地震局地球物理研究所,1999.
[24]丁志峰,何正勤,孙为国,等.青藏高原东部及其边缘地区的地壳上地幔三维速度结构[J].地球物理学报1999,42(2):197-205.
[25]Humphreys E,Clayton R W.Adaptation of back projection tomography to seismic travel time problems[J].J.Geophys.Res.,1988,93:1073-1085.
[26]徐文耀,祁揆,王仕明.甘肃东部地区短周期地磁变化异常及其与地震的关系[J].地球物理学报,1978,21(3):218-224.
[27]张必敖,董冶平,韩友珍.南北地震带北段地温场的初步探讨[J].西北地震学报,1987,9(1):26-32.
[28]滕吉文,张中杰,胡家富,等.青藏高原整体隆生与地壳缩短增厚的物理——力学机制研究(下)[J].高校地质学报,1996,2(3):307-323.
[29]滕吉文.固体地球物理学概论[M].北京:地震出版社,2003.
[30]孙鸿烈,郑度.青藏高原形成、演化与发展[M].广州:广东科技出版社,1998.
[31]刘百篪.青藏高原的新生代重要地质事件与构造演化[A]∥中国地震学研究进展[G].北京:地震出版社,1997.
[32]王椿镛,W D Mooner,王溪莉,等.川滇地区地壳上地幔三维速度结构研究[J].地震学报,2002,24(1):1-16.
[33]Mooney W D,Brocher T M.Coincident seismic reflection/refraction studies of the continental lithosphere:A global re-wiew[J].Rev.Geophys,1987,25:723-742.
[34]郭增建,秦保燕,徐文耀,等.震源孕育模式的初步讨论[J].地球物理学报,1973,16:43-48.
[1]曾融生,滕吉文,阚荣举,等.我国西北地区地壳中的高速夹层[J].地球物理学报,1965,14(2):94-106.
[2]林中洋,蔡文伯,陈学波,等主编.青海门源至福建宁德地学断面[M].北京:地震出版社,1992.
[3]王椿镛,林中洋,陈学波.青海门源-福建宁德地学断面综合地球物理研究[J].地球物理学报,1995,38(5):590-598.
[4]孙武城,徐杰,杨主恩,等主编.上海奉贤至内蒙古阿拉善左旗地学断面[M].北京:地震出版社,1992.
[5]闵祥仪,周民都,郭建康,等.灵台-阿木去乎剖面地壳速度结构[J].西北地震学报,1991,13(增刊):29-36.
[6]李清河,郭建康,周民都,等.成县-西吉剖面地壳速度结构[J].西北地震学报,1991,13(增刊):37-43.
[7]李松林,张先康,张成科,等.玛沁—兰州—靖边地震测深剖面速度结构的初步研究[J].地球物理学报,2002,45(2):210-217.
[8]周民都,吕太乙,张元生,等.青藏高原东北缘地质构造背景及地壳结构研究[J].地震学报,2000,22(6):645-653.
[9]刘建华,刘福田,吴华,等.中国南北带地壳和上地幔的三维速度结构[J].地球物理学报,1989,32(2):143-151.
[10]李清河,郭守年,吕德徽.鄂尔多斯西缘与西南缘深部结构与构造[M].北京:地震出版社,1999.
[11]任纪舜,姜春发,张正坤,等.中国大陆构造及其演化[M].北京:科学出版社,1981.
[12]国家地震局“鄂尔多斯周缘活动断裂系”课题组.鄂尔多斯周缘活动断裂系[M].北京:地震出版社,1988.
[13]王萍,王增光.阿拉善活动地块的划分及归宿[J].地震,1997,17(1):103-112.
[14]李玉龙,邢成起.河西走廊地质构造基本特征以及榆木山北麓与黑河口上龙王活断层研究[J].西北地震学报,1988,10(2):35-47.
[15]王清晨,孙枢,李继亮,等.秦岭的大地构造演化[J].地质科学,1989,(2):129-142.
[16]刘树根,罗志立,戴苏兰,等.龙门山冲断带的隆升和川西前陆盆地沉降[J].地质学报,1995,69(3):205-214.
[17]Aki K,Lee W H K.Determination of three dimensional ve-locity anomalies under a seismic array using first P arrival times from local earthquakes1.A homogeneous initial model[J].J.Geophys.Res.,1976,81:4381-4399.
[18]Zhao D,Horiuchi S,Takagi A.3-D seismic velocity struc-ture of the crust and the uppermost mantle in the northeast-ern Japan arc[J].Tectonopgysics,1990,181:135-149.
[19]Zhao D.A tomographic study of seismic velocity structure in the Japan Islands[D].Tohoku University,1991.
[20]Zhao D,Hasegawa A,Horiuchi S.Tomographic imaging of P and S wave velocity structure beneath northeastern Japan[J].Journal of Geophysical Research,1992,97(B13):19909-19928.
[21]Zhao D,Hasegawa A.P wave tomographic imaging of the crust and upper mantle beneath the Japan Islands[J].Jour-nal of Geophysical Research,1993,98(B3):4333-4353.
[22]Zhao D.Deep structure of Japan subduction zone as derived from local,regional,and teleseismic events[J].Journal of Geophysical Research,1994,99(B11):22313-22329.
[23]丁志峰.近震层析成像的理论与应用[D].北京:中国地震局地球物理研究所,1999.
[24]丁志峰,何正勤,孙为国,等.青藏高原东部及其边缘地区的地壳上地幔三维速度结构[J].地球物理学报1999,42(2):197-205.
[25]Humphreys E,Clayton R W.Adaptation of back projection tomography to seismic travel time problems[J].J.Geophys.Res.,1988,93:1073-1085.
[26]徐文耀,祁揆,王仕明.甘肃东部地区短周期地磁变化异常及其与地震的关系[J].地球物理学报,1978,21(3):218-224.
[27]张必敖,董冶平,韩友珍.南北地震带北段地温场的初步探讨[J].西北地震学报,1987,9(1):26-32.
[28]滕吉文,张中杰,胡家富,等.青藏高原整体隆生与地壳缩短增厚的物理——力学机制研究(下)[J].高校地质学报,1996,2(3):307-323.
[29]滕吉文.固体地球物理学概论[M].北京:地震出版社,2003.
[30]孙鸿烈,郑度.青藏高原形成、演化与发展[M].广州:广东科技出版社,1998.
[31]刘百篪.青藏高原的新生代重要地质事件与构造演化[A]∥中国地震学研究进展[G].北京:地震出版社,1997.
[32]王椿镛,W D Mooner,王溪莉,等.川滇地区地壳上地幔三维速度结构研究[J].地震学报,2002,24(1):1-16.
[33]Mooney W D,Brocher T M.Coincident seismic reflection/refraction studies of the continental lithosphere:A global re-wiew[J].Rev.Geophys,1987,25:723-742.
[34]郭增建,秦保燕,徐文耀,等.震源孕育模式的初步讨论[J].地球物理学报,1973,16:43-48.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心