川滇地区上地幔顶部Pn速度细结构
摘要
利用中国地震年报、四川和云南区域地震台网观测报告的23298个Pn波到时资料,反演得到川滇地区及周边的Pn波速度细结构及各向异性。结果表明:该区Pn波速度在7.7～8.3km/s范围内变化,横向变化较为明显,在滇西南部、腾冲火山区、攀西构造带,Pn波速度都明显较低,这些地区地震和构造活动十分活跃,且在地表观测到较高的大地热流值;另一方面较为稳定的地区,如:扬子地合中部,Pn波速度相对较高;研究区内最明显的Pn高速区位于成都东南部的四川盆地;上述结果说明该区Pn波速度与现代构造活动及地热活动存在较明显的关联。Pn各向异性的变化呈现出区域内岩石形变的复杂图像,从藏东块体经川滇菱形块体到滇西南部,Pn快波方向里左旋运动,这可能与印-欧板块碰撞挤压,致使青藏高原物质向东南方向逃逸有关。由此表明区域内壳幔间存在较强的耦合关系,由事件和台站的静延迟分布可以看出从青藏高原到中国东部地区地壳由厚减薄,这与人工地震测深所得到的地壳厚度变化具有较好的一致性。
引文
1 胡鸿翔,陆涵行,王椿镛,等.滇西地区地壳结构的爆破地震研究.地球物理学报,1986,29:133～144
2 熊绍柏,腾吉文,尹周勋,等.攀西构造带南部地壳与上地幔结构的爆炸地震研究.地球物理学报,1986,29:235～245
3 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图像.地球物理学报,1989,32:143～151
4 Huang J L, Zhao D P, Zheng S H. Lithopheric structure and its relationship to seismic and volcanic activity in southwest China. J Geophys Res, 2002． 107, NO. BIO, 2255, doi: 10． 1029/2000JB000137
5 吴建平,明跃红,王春镛.云南数字地震台网下方的S波速度结构研究.地球物理学报,2001,44:228～237
6 Silver P G,Chan W W.Implication for continental structure and evolution from seismic anisotropy. Nature, 1988, 335: 34～49
7 Vinnik L P, Makeyeva L I, Milev A, et al. Global patterns of azimuthal anisotropy and deformation in the continental mantle.Geophys J Int, 1992, 111: 433～477
8 Hearn T M. Anisotropic Pn tomography in the western united States. J Geophys Res, 1996, 101: 8403～8414
9 Hearn T M, Beghoul N, Barazangi M. Tomography of the western united States from reginal arrival time. J Geophys Res,1991, 96: 16369～16381
10 Paige C C, Saunders M A. LSQR: An algorithm for sparse linear equations and sparse least squares. ACM Trans Math Software, 1982, 8: 43～71
11 汪素云,Hearn T M,许忠淮,等.中国大陆上地幔顶部Pn速度结构.中国科学,D辑,2001,31:449～454
12 Hearn T M, Ni J F.Pn velocities beneath continental collision zone: the Turkish-Iran Plateau. Geophys J Int, 1994, 117:273～283
13 阚荣举,赵晋明,阚丹.腾冲火山地热区的构造演化与火山喷发.地震地磁观测与研究,1996,17:28～32
14 滕吉文.康滇构造带岩石圈物理与动力学.北京:科学出版社,1994
15 Hu S, He L,Wang J. Heat flow in the continental area of China: a new data set. Earth Planet Sci Lett, 2000, 179: 407～419
16 Holt W E, Li M, Haines A J. Earthquake strain rates and instantaneous relative motions within central Asia. Geophys J Int,1995, 122: 569～593
17 Wang Q, Zhang P, Jeffrey T,et al. Present-Day Crustal deformation in china constrained by Global positioning system measurements. Science, 2001, 294: 574～577
18 郑斯华,高原.中国大陆岩石层方位各向异性.地震学报,1994,16:131～140
19 朱介寿,严忠琼,姚宇峰.Moho 界面深度图.见:袁学诚,主编.中国地球物理图集.北京:地质出版社,1996． 176～177
2 熊绍柏,腾吉文,尹周勋,等.攀西构造带南部地壳与上地幔结构的爆炸地震研究.地球物理学报,1986,29:235～245
3 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图像.地球物理学报,1989,32:143～151
4 Huang J L, Zhao D P, Zheng S H. Lithopheric structure and its relationship to seismic and volcanic activity in southwest China. J Geophys Res, 2002． 107, NO. BIO, 2255, doi: 10． 1029/2000JB000137
5 吴建平,明跃红,王春镛.云南数字地震台网下方的S波速度结构研究.地球物理学报,2001,44:228～237
6 Silver P G,Chan W W.Implication for continental structure and evolution from seismic anisotropy. Nature, 1988, 335: 34～49
7 Vinnik L P, Makeyeva L I, Milev A, et al. Global patterns of azimuthal anisotropy and deformation in the continental mantle.Geophys J Int, 1992, 111: 433～477
8 Hearn T M. Anisotropic Pn tomography in the western united States. J Geophys Res, 1996, 101: 8403～8414
9 Hearn T M, Beghoul N, Barazangi M. Tomography of the western united States from reginal arrival time. J Geophys Res,1991, 96: 16369～16381
10 Paige C C, Saunders M A. LSQR: An algorithm for sparse linear equations and sparse least squares. ACM Trans Math Software, 1982, 8: 43～71
11 汪素云,Hearn T M,许忠淮,等.中国大陆上地幔顶部Pn速度结构.中国科学,D辑,2001,31:449～454
12 Hearn T M, Ni J F.Pn velocities beneath continental collision zone: the Turkish-Iran Plateau. Geophys J Int, 1994, 117:273～283
13 阚荣举,赵晋明,阚丹.腾冲火山地热区的构造演化与火山喷发.地震地磁观测与研究,1996,17:28～32
14 滕吉文.康滇构造带岩石圈物理与动力学.北京:科学出版社,1994
15 Hu S, He L,Wang J. Heat flow in the continental area of China: a new data set. Earth Planet Sci Lett, 2000, 179: 407～419
16 Holt W E, Li M, Haines A J. Earthquake strain rates and instantaneous relative motions within central Asia. Geophys J Int,1995, 122: 569～593
17 Wang Q, Zhang P, Jeffrey T,et al. Present-Day Crustal deformation in china constrained by Global positioning system measurements. Science, 2001, 294: 574～577
18 郑斯华,高原.中国大陆岩石层方位各向异性.地震学报,1994,16:131～140
19 朱介寿,严忠琼,姚宇峰.Moho 界面深度图.见:袁学诚,主编.中国地球物理图集.北京:地质出版社,1996． 176～177
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