| 海底地震仪远震记录接收函数反演——以南海西南次海盆为例 |
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| 引用本文： | 胡昊,阮爱国,游庆瑜,李家彪,郝天珧,龙江平.海底地震仪远震记录接收函数反演——以南海西南次海盆为例[J].地球物理学报,2016,59(4):1426-1434. |
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| 作者姓名： | 胡昊 阮爱国 游庆瑜 李家彪 郝天珧 龙江平 |
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| 作者单位： | 1. 国家海洋局第二海洋研究所, 杭州 310012;2. 中国科学院地质与地球物理研究所, 北京 100029 |
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| 基金项目： | 国家基金委重大研究计划重点支持项目(91028006;91228205);国家自然科学基金(41576037)资助 |
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| 摘 要： | 由于海底环境和海底地震仪(OBS)结构的特殊性,用OBS远震记录进行接收函数岩石圈反演研究因为存在一定的困难,所以还很少见.在深入分析问题的基础上,以国产I-4C型宽频带OBS在南海西南次海盆记录的天然地震为实例,我们将傅里叶变换和小波变换相结合以压制海底地震仪记录中的非平稳干扰,获得了信噪比较高、震相清晰的地震记录,进而成功开展了远震记录的岩石圈结构接收函数反演.主要结论是:(1)OBS接收函数的求取是可行的,关键是压制非平稳干扰.(2)西南次海盆的Moho面埋深为海底下10~12km(地壳厚6~8km),沉积物厚度为1~2km,浅部地壳存在低速区,与沉积物和海底扩张停止后的岩浆喷发产生的岩石碎屑和裂隙有关.(3)在扩张脊中央Moho面上方6~12km存在S波低速区,推测扩张中心可能存在下地壳熔融或岩浆房,在17~30km区间S波速度呈负梯度,我们认为扩张中心更深的地方存在热物质的供给.
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| 关 键 词： | 海底地震仪 接收函数 南海西南次海盆 洋壳S波速度 岩石圈结构 |
| 收稿时间： | 2015-01-28 |
Using OBS teleseismic receiver functions to invert lithospheric structure —A case study of the southwestern subbasin in the South China Sea |
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| HU Hao;RUAN Ai-Guo;YOU Qing-Yu;LI Jia-Biao;HAO Tian-Yao;LONG Jiang-Ping.Using OBS teleseismic receiver functions to invert lithospheric structure —A case study of the southwestern subbasin in the South China Sea[J].Chinese Journal of Geophysics,2016,59(4):1426-1434. |
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| Authors: | HU Hao;RUAN Ai-Guo;YOU Qing-Yu;LI Jia-Biao;HAO Tian-Yao;LONG Jiang-Ping |
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| Institution: | 1. The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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| Abstract: | Due to the particular seafloor environment and special outer mechanical structure of the ocean bottom seismometer (OBS), there are some problems which have not been solved in the lithospheric structure inversion using OBS teleseismic receiver functions. Based on the analysis of these problems, we combined the Fourier transform and wavelet analysis to suppress the non-stationary noise to obtain a better signal-to-noise ratio and clearer seismic phases recorded by the OBSs at the southwestern subbasin in the South China Sea (SCS). The equipment is broadband OBS of I-4C type produced by the Institute of Geology and Geophysics, Chinese Academy of Sciences. We then inverted the lithospheric structure by applying receiver functions to the teleseismic data recorded at the southwestern subbasin of the SCS successfully. The results show that it is feasible to use receiver functions for the inversion of lithosphere structure based on the passive observation data by OBS, in which the key is to suppress the non-stationary noise. The Moho depth in the southwestern subbasin of the SCS is 10~12 km with crust thickness of 6~8 km. The shallow crust is a low velocity layer with sediment thickness 1~2 km which consists of sediment and volcanic clastic breccia produced by magma eruption after spreading cessation. In the spreading axis center there is a low S-wave velocity zone at the depth of 6 km to 12 km above Moho. We interpreted it as the result of partial melting of the lower crust or the presence of a magma chamber. In the same area at the depth of 17 km to 30 km the vertical S-wave velocity gradient is negative. We interpreted it as the result of hot magma supply upward in the mantle. |
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| Keywords: | Ocean bottom seismograph Receiver functions Southwestern subbasin in the SCS S-wave velocity structure of oceanic crust Lithosphere structure |
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