中国大陆岩石层的方位各向异性
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摘要: 采用理论地震图与观测地震记录直接比较的方法, 研究了中国数字地震台网宽频带记录的SKS震相的剪切波分裂现象, 确定了快速S波的振动方向和慢速S波的时间延迟。结果表明, 对于所分析的8个观测台均发现了明显的S波分裂现象, 时间延迟在0.7s与1.7s之间。这种经过地幔传播的SKS震相的S波分裂现象的主要原因是上地幔的各向异性。上地幔的各向异性可以用应变引起的上地幔中的矿物质的结晶优势排列来解释。根据时间延迟估计的各向异性层的厚度, 与由上地幔中的高导层和低速层所推断的中国大陆下岩石层的厚度大致相符。在大部分台站上, 反演得到的快速S波的振动方向与由亚板块总体形变推测的结果相一致。个别台站具有较大的差异, 说明S波分裂这一观测事实的起因是复杂的。为了进一步解释S波分裂的结果, 还需要更多高质量的观测资料, 以及关于原地介质状态的更详细的信息。
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[6] Ando, M., Ishikawa, Y. and Wada, H., 1980. S——wave anisotropy in the upper mantle under a volcanic area in Japan. Nature, 288, 93——56
[7] Dziewonski, A. M. and Andorson, D. L., 1981. Preliminary reference earth model. Phys. Earth PlaueL. Int., 25, 297——356.
[8] Fukao, Y., 1989. Evidence from core——reflected shear waves for anisotropy in the earth's mantle. Nature, 309, 695——698.
[9] Mochizuki, E., 1986. The free oscillations of an anisotropic and heterogeneous earth. Geoyhys. J. Roy. asEr. Soc., 88, 167——176.
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[11] Shimamura, H., Asada, T., Suehiro, K., Yamada, T. and Inatani, H., 1983. Longshot experiments to study velocity anisotropy in the oceanic lithosphere of the northwestern Pacific. Phys. Earth Planet. Int., 3I, 398——362.
[12] Silver, P. G. and Chan, W. W., 1988. Implications for continental structure and evolution from seismic anisotropy. Nature, 335, 39——39.
[13] Silver, P. G. and Chan, W. W., 1991. Shear wave splitting and subcontinental mantle deformation. J. Ceophys. Res., 96, 16929——16954.
[14] Tanimoto, T. and Anderson, D. L., 1989. Mapping convection in the mantle. GeoPhys. Res. Left., 84, 287——290.
[15] V innik, L. P., Farra,V. and Romanowwicz, B., 1989. Azimuthal anisotropy in the earth from observation of SKS at GEOSCOPE and NARS broadband stations. Bull. Seism. Soc. Amer., 79, 1542——1558.
[16] Vinnik, L. P., Kind, R., Kosarev, G. L. and Makeyeva, L. I., 1989b. Azimuthal anisotropy in the lithosphere from observations of long——period S waves. CeoPhys. J. Int., 99, 549——559.[1] 丁国瑜、卢演涛,1989.板内块体的现代运动, 中国岩石圈动力学地图集, p. 21.马杏垣(主编).地质出版社, 北京.
[2] 丁国瑜、卢演侍,1991.活动亚板块、构造块体的相对运动, 中国岩石圈动力学概论, 142——152.丁国瑜(主编).地震出版社, 北京.
[3] 刘国栋、朱英.1991.岩石圈的非均匀性及结构的基本特征, 中国岩石圈动力学概论, 76——90.丁国瑜(主编).地震出版社, 北京.
[4] 宋仲和、安昌强、陈立华、仇志荣, 1986.中国大陆和边缘海的上地慢P波速度结构.地震学报, 8. 263——274.
[5] 中国数字地震台网, 1990.中国数字地震台网文集,1——989.学术书刊出版社, 北京.
[6] Ando, M., Ishikawa, Y. and Wada, H., 1980. S——wave anisotropy in the upper mantle under a volcanic area in Japan. Nature, 288, 93——56
[7] Dziewonski, A. M. and Andorson, D. L., 1981. Preliminary reference earth model. Phys. Earth PlaueL. Int., 25, 297——356.
[8] Fukao, Y., 1989. Evidence from core——reflected shear waves for anisotropy in the earth's mantle. Nature, 309, 695——698.
[9] Mochizuki, E., 1986. The free oscillations of an anisotropic and heterogeneous earth. Geoyhys. J. Roy. asEr. Soc., 88, 167——176.
[10] Nicolas, A. and Poirier, J. P., 1976. Crystalline Plasticity and Solid Slate Flow in Metamorphic Rocks, pp949. John Wiley and Sons, New York.
[11] Shimamura, H., Asada, T., Suehiro, K., Yamada, T. and Inatani, H., 1983. Longshot experiments to study velocity anisotropy in the oceanic lithosphere of the northwestern Pacific. Phys. Earth Planet. Int., 3I, 398——362.
[12] Silver, P. G. and Chan, W. W., 1988. Implications for continental structure and evolution from seismic anisotropy. Nature, 335, 39——39.
[13] Silver, P. G. and Chan, W. W., 1991. Shear wave splitting and subcontinental mantle deformation. J. Ceophys. Res., 96, 16929——16954.
[14] Tanimoto, T. and Anderson, D. L., 1989. Mapping convection in the mantle. GeoPhys. Res. Left., 84, 287——290.
[15] V innik, L. P., Farra,V. and Romanowwicz, B., 1989. Azimuthal anisotropy in the earth from observation of SKS at GEOSCOPE and NARS broadband stations. Bull. Seism. Soc. Amer., 79, 1542——1558.
[16] Vinnik, L. P., Kind, R., Kosarev, G. L. and Makeyeva, L. I., 1989b. Azimuthal anisotropy in the lithosphere from observations of long——period S waves. CeoPhys. J. Int., 99, 549——559.
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