| 大别造山带地壳S波速度结构 |
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| 引用本文： | 王椿镛,宋建立.大别造山带地壳S波速度结构[J].地球物理学报,1997,40(3):337-346. |
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| 作者姓名： | 王椿镛 宋建立 |
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| 作者单位： | 1. 国家地震局地球物理研究所, 北京 100081;
2. 国家地震同地球物理勘探中心, 郑州 450003 |
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| 基金项目： | 国家自然科学基金，地震科学联合基金，国家地震局资助项目 |
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| 摘 要： | 在大别造山带深地震测深剖面H维P波地壳速度结构的基础上,从地震记录的水平分量得到S波地壳速度结构,并用P波和S波的资料共同约束地壳的组成.剖面上大多数炮点的记录均显示了清晰的Sg和SmS震相.在埠塔寺炮和金拱炮的记录上还较清晰地显示出莫霍界面的反射转换震相PmS,表明在相应的范围内莫霍界面是一级间断面.在Pn和SmS震相都比较强的记录截面图上缺少相应的Sn震相,表示在上地幄顶部泊松比随深度急剧增大,在这一深度上物质可能存在局部熔融状态.剖面的地壳泊松比模型表明,上地壳在深度10km以内泊松比为025左右,仅北淮阳弧后复理石带较低,为0.23；扬子板块和华北板块的下地壳泊松比为0.26-0.27；在大别选山带,上地壳下部泊松比为0.22-0.24,而下地壳泊松比为0.27-0.30,其中超高压变质带最高.P、S波速度和泪松比表明超高压变质带下地壳主要由基性麻粒岩组成.大别造山带中、下地壳组成的横向不均匀性反映了在三叠纪造山作用期间扬子板块向华北板块俯冲,以及存在与地慢物质相联系的岩浆侵入体.
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| 关 键 词： | 大别造山带 超高压变质带 深地震测深剖面 S波速度结构 |
| 收稿时间： | 1996-07-10 |
SHEAR WAVE VELOCITY STRUCTURE IN DABIESHAN OROGENIC BELT |
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| WANG CHLJN-YONGJ,DING ZHI -FENG,SONG JIAN-LI,WU QING-JU,ZHENG JI -CAI,ZHANG XIAO-BINGl.SHEAR WAVE VELOCITY STRUCTURE IN DABIESHAN OROGENIC BELT[J].Chinese Journal of Geophysics,1997,40(3):337-346. |
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| Authors: | WANG CHLJN-YONGJ DING ZHI -FENG SONG JIAN-LI WU QING-JU ZHENG JI -CAI ZHANG XIAO-BINGl |
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| Institution: | 1. Institute of Geophysics, State Seismological Bureau, Beijing 100081, China;
2. Geophysical Prospecting Cealer, State Seismological Bureau, Zheagzhou 450003, China |
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| Abstract: | Based on the 2-D P wave velocity structure from the deep seismic sounding prcrfile across the Dabieshan orogenic belt, the horizontal components of seismic recordswere used to determine the shear wave velocity structure. And then, the data of Pwave and S wave were jointly used to restrain the composition of crust' The phasesSg and SmS appear clearly on the records of most shotpoints, and the converted wavePmS reflected from the Moh0 shows on the records of the Butasi and the Jing0ngshotpoints. lt indicates that the Moho is a first-order disc0ntinuity onthe relevant re-gion. That the record containing both strong Pn and SmS is lacking in the related Snmay indicate that the P0isson ratio in the uPpermost mantle increases shmp1y Withdepth, and the locally melting material may ekist at this dePth' The model of thePoisson ratio in crust dem0nstrates that it is about O'25 at the depth Iess than lOtriin the uPper crust along the whole proflle except the North Huayang Flysch Beltwhere it is O'23, O'26 - O'27 in the lower crust of both the Yangtze block and N0rthChina block, O-22- 0-24 in the lower part of the uPper crust and O'27- 0-3O in thelower crust in the Dabieshan or0genic belt, where it is the highest in the Ultra-HighPressure belt' The P, S velocities and P0isson rati0 j0intly il1ustrate that the basicgranulite is the main c0mp0sition of the l0wer crust in the Ultra-High Pressure belt'The lateral heterogeneity of the composition in the mid~lower crust of the Dabieshanorogenic belt indicates that the Yangtze block subducted to the North Chna block inthe Triassic orogeny, and the magma intrusion related t0 the mantle material mayekist there' |
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| Keywords: | Dabieshan orogenic belt Ultra-high pressure metamorphic belt Deepseismic sounding profile S-wave velocity crustal structure |
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