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91.
深地震反射原始单炮数据是非平稳的弱能量反射信号,信噪比较低.如何提高信噪比一直是深地震反射数据前处理中的一大难题.S变换是一种适用于分析非平稳信号的时频变换方法.同其他分析时变信号的方法相比,S变换的基本小波不必满足小波在时间域均值为零的容许性条件,它的时频分辨率与分析信号的频率有关,且其在时间域的积分可以得到傅里叶频谱,其反变换也简单.因此,S变换容易表示深地震反射信号复杂的时频特性.本文在S变换的基础上,利用软阈值滤波方法对深地震反射数据进行处理,实验结果表明,该方法有效地提高了信噪比,压制了有效频带范围内的混频干扰,突出了弱反射信号,使得波组信息更加丰富,有利于连续追踪有效反射波组和识别薄地层,特别是提高了深部Moho界面反射层位的分辨率,为深地震反射剖面后续处理和准确解释奠定了基础. 相似文献
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基于1996—2012年西北太平洋Argo剖面浮标盐度观测资料,利用合成分析方法研究了海表面盐度对台风的响应特征。结果表明海表面盐度对台风的响应具有明显的非对称性:台风过后其路径右侧的海表面盐度显著上升;左侧的则在R50内上升,R50外区域普遍下降。进一步分析显示台风强度、移动速度和海洋混合层深度对海表面盐度响应特征均有较大影响。强度大或移动缓慢的台风能造成大范围的海表面盐度上升;强度小或移动快速的台风只在路径右侧造成海表面盐度上升,左侧的则普遍下降。夏季(6-9月)台风过后,海表面盐度在混合层浅的区域普遍大幅上升,在混合层深的区域则在台风路径左右两侧2R50范围内小幅上升,在远离台风路径左侧区域下降。 相似文献
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东海试验区水体光谱特性现场测量与数据分析 总被引:6,自引:1,他引:5
星载水色遥感器 Sea Wi F S 已业务化地为海洋学家提供高质量的海洋水色遥感数据。要有效地利用水色遥感数据,需要经常地对遥感器进行定标,并对测得的离水辐射率以及导出的生物—光学特性进行真实性检验。1998 年5 月, 我们在东海试验区,应用多光谱剖面/ 表面辐射仪( S P M R/ S M S R) ,进行了光谱测量。本文介绍了现场测量的方法,以及根据我国海区的特点对实测数据的处理结果 相似文献
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L. Guglielmetti F. Poletto P. Corubolo A. Bitri C. Dezayes B.M. Farina F. Martin F. Meneghini A. Moscariello C. Nawratil de Bono A. Schleifer 《Geophysical Prospecting》2020,68(4):1139-1153
This paper deals with the design, acquisition and processing of vertical seismic profiling data collected in 2016 at the directional Thônex-01 geothermal well, drilled in 1993 in the Geneva Canton (Switzerland). The aim of the study was to obtain additional information from existing-abandoned well for downhole geophysical characterization of potential geothermal reservoirs in the Geneva area. The main results obtained by this study allowed an improved subsurface image by multi-offset acquisitions near and around the deviated well. Specifically we were able to (1) improve the velocity model of the Geneva Basin, which, at present, is only constrained by one unique deep exploration well, located at the south-west of the basin, far away from the study area; (2) image the transition between the Tertiary Molasse siliciclastic sediments and the Mesozoic carbonates; (3) define an acquisition strategy for future vertical seismic profiling surveys in support of the geothermal exploration campaigns in the area. This study has demonstrated the value of vertical seismic profiling method for the refinement of the subsurface geology at local scale, and its usefulness to assist the planning of second well associated with geothermal doublets. 相似文献
98.
青藏高原地壳变形加厚机制一直是地学界研究争论的热点问题.青藏高原目前仍然处在持续向外扩张之中,因此青藏高原的边界地带作为高原向外扩张的最前缘地区代表了高原最新的变形状态,是研究青藏高原地壳变形加厚的关键地区.本文以一条穿过青藏高原东北缘祁连山与酒西盆地结合部的深地震反射剖面为基础,结合前人地质、地球物理资料,通过细致的地质构造解译,获得青藏高原东北缘祁连山与酒西盆地结合部位地壳变形以壳内滑脱带为界上、下解耦.滑脱带位于壳内低速层的顶部,深度14~24 km.滑脱带之上的地壳部分以一系列南倾、北冲,并向下终止于滑脱带的逆冲断裂变形为主,指示了青藏高原向北的扩张方式;滑脱带之下的地壳以Moho面作为变形标志,指示了复杂的挤压缩短变形.据此我们推测上、下地壳的解耦缩短变形对青藏高原东北缘地壳的变形加厚起到了决定性的作用,甚至在整个青藏高原地壳的变形加厚过程中都起到了重要作用. 相似文献
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THE FINE CRUSTAL STRUCTURE OF THE SOUTHERN MARGIN OF NORTH CHINA BLOCK REVEALED BY DEEP SEISMIC REFLECTION PROFILE 下载免费PDF全文
FENG Shao-ying LIU Bao-jin LI Qian YUAN Hong-ke ZHU Guo-jun TIAN Yi-ming WANG Hong-wei HOU Li-hua DENG Xiao-juan TAN Ya-li 《地震地质》1979,42(3):581-594
The study area is located at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China Block. In order to study the fine crustal structure and the deep-shallow structural features of faults in this area, we conducted deep seismic reflection profiling with the seismic profile of 100km long, directing NE-SW in Zhumadian City, Henan Province, and got clear lithospheric structure images along the profile. As regards the data acquisition, we applied the geometry of 25m group interval, 1 000 recording channels and more than 60 folds. Seismic wave exploding applies the 30kg shots of dynamite source with the borehole depth of 25m. The shot interval is 200m. In data processing, we focused on improving the signal-to-noise ratio. Data processing methods mainly include first break removal, tomographic static correction, abnormal amplitude elimination, amplitude compensation, pre-stack denoising, surface consistent deconvolution, velocity analysis, several iterations of the residual static correction, dip moveout, post-stack time migration and post-stack denoising, etc. The profile with high signal-to-noise ratio was obtained. The reflection wave group characteristics is obvious in the crust, which reflects abundant information about geological structure. Along the profile, the crust is characterized by double-layer reflection structure, and the Moho surface is composed of a series of laminated arc-shaped strong reflections. The thickness of the upper crust is about 14.8~20.7km, and the total thickness of the crust is about 32.0~35.1km. The upper crust is dominated by the inclined, densely stratified or arc-shaped reflections. The lower crust is dominated by arc-shaped and inclined reflection, and there is a reflective transparent zone under the Moho surface. The reflection sequences with different directions and shapes in the upper crust constitute the nappe structure in southwest segment and the structural model of two concaves with one uplift in NE segment, which correspond to the north Qinling nappe, Zhumadian-Huaibin depression, Pingyu-Xiping uplift and a secondary depression, respectively. There are abundant arc-shaped reflection sequences in the lower crust, which may represent multi-stage magmatic activities. The deep seismic reflection profile shows that faults in the upper crust are well developed. According to the characteristics of reflected wave field in the profile, four groups of fault structure which contain ten faults with different scales are interpreted. Among them, faults FP1, FP2 and FP3 constitute the thrust fault system in the northern margin of Qinling Mountains, and FP5 and FP7 are boundary faults of Zhumadian-Huaibin depression. These faults are all developed within the upper crust. In addition, the Fault FPM is a large fault that cuts through the lower crust and Moho surface. The deep seismic reflection profile reveals the crustal structure and deep-shallow structural features of faults at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China block, which provides seismological evidence for the analysis of structural differences, the deep earth's interior processes and deep-shallow structural relationships between the Qinling-Dabie orogenic belt and the southern margin of the North China block. The lower crust of the study area is divided into two parts by deep faults that dislocate the Moho surface. These two parts have distinct reflective structures, suggesting that the area has experienced intense complex tectonic movements. The faults in the upper crust control the formation of basin-mountain structure and stratigraphic deposition of this area. And deep faults in the crust that disrupt Moho surface create conditions for the upwelling and energy exchange of deep materials. All of these have regulated the composition of material and the distribution of energy in the crust. The deep faults cutting through the lower crust and Moho surface and the south-dipping arc-shaped and inclined strong reflection sequences developed in the lower crust should indicate the large-scale subduction of the southern margin of the North China block towards the south-trending Qinling orogenic belt. 相似文献