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由于长排列广角地震采集中必定存在超临界角的广角反射信息,广角反射信息相对临界角内反射信息存在随偏移距变化的时移现象.本文研究了去广角效应下的走时反演成像,并将其应用到东南屯溪—温州的宽角地震资料.通过拾取中国东南屯溪—温州剖面宽角实际地震资料中P波垂直分量拾取到的反射P波走时,继而使用遗传反演方法进行处理,得到了该区丰乐、新安江、松阳、青田以及洞头五炮去广角效应与未考虑广角效应情况下的一维速度深度曲线,并对比了去广角效应前后的地壳结构界面形态.结果表明,广角效应去除前后影响主要体现在壳内层速度差异,地壳浅层界面深度的广角效应明显强于深层界面. 相似文献
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滇西孟连-马龙宽角反射地震剖面切过保山地块(冈瓦纳型), 思茅地块和扬子地块(扬子型)西南部. 通过解释宽角反射地震资料, 获得了这3个地块与昌宁-孟连和墨江缝合带的壳/幔纵波速度结构及相应的地壳和上地幔反射结构图像. 结果表明:思茅地块的地壳P波速度较之保山和扬子地块西南部低, 地壳厚度由保山地块、思茅和扬子地块西南部逐渐增厚. 这三个地块的地壳反射图像也具有明显的差异. 冈瓦纳型地块内上地壳反射发育, 而中下地壳反射很弱. 扬子型地块内地壳反射发育. 思茅与扬子地块西南部反射图案有明显的特殊性. 研究区地壳厚度为 40 km左右. 最后对滇西三个地块的地壳增厚的方式、地震孕育的构造环境冈瓦纳型和扬子型地块的相互作用进行了讨论. 相似文献
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云南思茅—中甸宽角反射/折射地震剖面切割松潘—甘孜、扬子和华南三个构造单元的部分区域. 我们利用初至波和壳内反射波走时层析成像获得地壳纵波速度结构. 在获得新的地壳速度结构模型基础上,利用地震散射成像思想和低叠加次数的叠前深度偏移方法重建了研究区的地壳、上地幔反射结构. 综合分析研究区地壳P波速度模型和壳内地震反射剖面发现:沿测线从北至南地壳厚度从约50 km减薄至35 km左右,地壳厚度的减薄量主要体现在下地壳,剖面北段下地壳厚度约为30 km,剖面南段下地壳厚度仅为15 km左右;上地幔顶部局部位置P波速度值偏低,一般为7.6~7.8 km/s,反映出云南地区是典型的构造活动区的特点.剖面沿线地壳内地震反射发育,其中莫霍强反射出现在景云桥下方;在景云桥弧形断裂带8~10 km深处出现宽约50 km的强反射带. 相似文献
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云南思茅—中甸宽角反射/折射地震剖面切割松潘—甘孜、扬子和华南三个构造单元的部分区域. 我们利用初至波和壳内反射波走时层析成像获得地壳纵波速度结构. 在获得新的地壳速度结构模型基础上,利用地震散射成像思想和低叠加次数的叠前深度偏移方法重建了研究区的地壳、上地幔反射结构. 综合分析研究区地壳P波速度模型和壳内地震反射剖面发现:沿测线从北至南地壳厚度从约50 km减薄至35 km左右,地壳厚度的减薄量主要体现在下地壳,剖面北段下地壳厚度约为30 km,剖面南段下地壳厚度仅为15 km左右;上地幔顶部局部位置P波速度值偏低,一般为76~78 km/s,反映出云南地区是典型的构造活动区的特点.剖面沿线地壳内地震反射发育,其中莫霍强反射出现在景云桥下方;在景云桥弧形断裂带8~10 km深处出现宽约50 km的强反射带. 相似文献
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采用深、浅地震反射和钻孔地质剖面相结合的探测方法,对太行山东缘汤阴地堑的地壳结构和隐伏活动断裂进行了研究.结果表明,该区地壳厚度约36~42 km,莫霍面从华北平原区向太行山下倾伏.汤阴地堑是一个受汤东断裂控制的半地堑构造,其基底面形态与莫霍面展布呈"镜像"关系.汤东断裂是1条继承性的隐伏活动断裂,该断裂向上错断了埋深约20 m的中更新世晚期地层,向下延伸至上地壳底部.综合分析深地震反射和已有深地震宽角反射/折射剖面结果,发现深地震反射剖面上的中-下地壳强反射层和壳幔过渡带反射,与深地震宽角反射/折射剖面上出现的中-下地壳正负速度梯度变化层有着较好的对应关系,这表明本区中-下地壳和壳幔过渡带可能为一系列速度递变层或高低速物质的互变层,埋深约15~16 km的强反射带为上地壳与中-下地壳的转换带,壳幔过渡带的底界为地壳与地幔的分界.研究结果为深入理解该区的深部动力学过程、分析研究深浅构造关系、评价断裂的活动性提供了依据. 相似文献
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利用地震波场研究地球内部壳、幔结构的方法主要包括天然地震波场中的远地震观测法、近地震观测法和人工源地震深部探测法.其中,由于人工源地震探测的震源位于浅表层介质中,且其震源位置、爆炸时间、接收条件等均为精确已知,因此其所得结果的精度最高、且最为准确.人工源深部地震探测分为深部地震宽角反射和折射剖面探测及深部近垂直反射波法探测.前者可求得壳、幔介质的分层结构和速度分布,后者可较详细了解地壳构造形态的细节.两种方法具有不同的特点、但却相辅相成.当今,将深地震宽角反射/折射和深反射法联合观测以取得较详细的速度结构和构造展布特征将必成地球内部研究的必然轨迹. 相似文献
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三江地区地壳结构及动力学意义:云南遮放-宾川地震反射/折射剖面的启示 总被引:11,自引:0,他引:11
位于中国云南省的三江地区的断裂主要包括金沙江-红河断裂、澜沧江断裂和怒江断裂(三江断裂带). 通过解释跨过滇西构造域中腾冲与保山地块的遮放-宾川宽角反射/折射地震剖面, 文中以地震波旅行时层析成像方法获得了地壳纵波速度结构, 以地震散射成像方法获得地壳反射结构, 从而重建了研究地区的地壳、上地幔反射结构. 给出的研究区地震P波速度和反射结构图像表明:该剖面的地壳结构可以划分为3个块体, 各块体间地壳速度与反射图像具有明显差异, 保山段地壳速度较东西两段为低, 莫霍界面反射强. 该地区地壳厚度为40 km左右, 并具有从西向东增厚的趋势. 腾冲南, 即剖面上80~115 km地段, 在8~10 km深处存在一组亮点形式的强反射带, 莫霍界面反射波场在横向变化明显. 对三江断裂地带地壳增厚的方式, 地震孕育的构造环境及腾冲、保山地块、潞西海槽之间的接触关系等问题进行了讨论. 相似文献
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During the Pamir Himalayan project in the year 1975 seismic refraction and wide-angle reflection data were recorded along
a 270 km long Lawrencepur-Astor (Sango Sar) profile in the northwest Himalayas. The profile starts in the Indus plains and
crosses the Main Central Thrust (MCT), the Hazara Syntaxis, the Main Mantle Thrust (MMT) and ends to the east of Nanga Parbat.
The seismic data, as published by Guerra et al. (1983), are reinterpreted using the travel-time ray inversion method of Zelt and Smith (1992) and the results of inversion
are constrained in terms of parameter resolution and uncertainty estimation. The present model shows that the High Himalayan
Crystallines (HHC, velocity 5.4 km s−1) overlie the Indian basement (velocity 5.8–6.0 km s−1). The crust consists of four layers of velocity 5.8–6.0, 6.2, 6.4 and 6.8 km s−1 followed by the upper mantle velocity of 8.2 km s−1 at a depth of about 60 km. 相似文献
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ZHU Jinfang XU Xiwei ZHANG Xiankang HUANG Zonglin CHEN Xiangxiong FANG Shengming LIU Baojin ZHENG Rongzhang . Seismological Bureau of Fujian Province Fuzhou China . Institute of Geology China Earthquake Administration Beijing China . Research Center for Exploration Geophysics China Earthquake Administration Zhengzhou China . State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing China 《中国科学D辑(英文版)》2005,48(7)
~~Joint exploration of crustal structure in Fuzhou basin and its vicinities by deep seismic reflection and high-resolution refraction as well as wide-angle reflection/refraction1.Ma,X.Y.,The Atlas of Lithospheric Dynamics of China(in Chinese),Beijing:Atlas Publishing Company,1989,1-68.
2.Liao,Q.L.,Wang,Z.M.,Wang,P.L.et al.,Explosion-generated earthquake study on crustal deep structure in Fuzhou-Quanzhou-Shantou region,Acta Geophysica Sinica(in Chinese),1988,31(3):270-280.
3.L… 相似文献
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ZHANG Zhongjie BAI Zhiming WANG Chunyong TENG Jiwen Lü Qingtian LI Jiliang LIU Yifeng & LIU Zhenkuan . Institute of Geology Geophysics Chinese Academy of Sciences Beijing China . Institute of Geophysics China Seismological Bureau Beijing China . Institute of Deposition Resource Chinese Academy of Geosciences Beijing China . School of Exploration Information China University of Geosciences Beijing China 《中国科学D辑(英文版)》2005,48(9):1329-1336
The Sanjiang area in southwest China is considered as a tectonic intersection belt between the Tethys-Alps and the western Pacific, and has endured three-phase evolution processes: Proto-Tethys,Paleo-Tethys and Meso-Tethys[1―4]. In this area, its tectonics and struc- ture are extremely complicated, and intensively extru-sive deformation and faults are widely developed[1―3]. For that, the area is considered as the ideal na- ture-laboratory to study the evolution of Paleo-Tethys and also … 相似文献
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偏移成像是VSP数据处理中的一个重要环节,常规的VSP成像方法通常利用VSP-CDP转换或Kirchhoff偏移,均存在保幅性差及成像精度低等问题,而波动方程叠前深度偏移被认为是对地下复杂构造进行成像的精确偏移方法.任意广角波动方程作为一种高精度的空间域单程波波动方程,同时由于只含有二阶偏导数项,易于数值实现,与其他单程波波动方程相比,具有更大的成像倾角,因此是偏移成像的有力工具之一.本文将AWWE推广应用到VSP数据成像中,实现了VSP时空域高角度单程波方程偏移.首先从三维标量任意广角波动方程出发,推导了完全匹配层吸收边界条件,在基本不增加计算量的前提下有效地压制了边界反射成像噪音,同时利用非线性反演算法优选参考速度来提高平方根算子的近似程度,从而提高高角度地层的成像精度.模型数值模拟实验验证了该方法的有效性,同时表明该方法在陡倾角构造情况下能取得很好的成像效果.最后对某地区实际观测的VSP资料进行了偏移成像,并与地面地震偏移结果进行了对比,显示出VSP波动方程偏移在成像分辨率上的优势. 相似文献
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R. F. Mereu 《Pure and Applied Geophysics》1990,132(1-2):269-288
ThePmP wide-angle reflected signal from the Moho shows a wide variation in its characteristics when cornpared from region to region. If the earth's crust is simple and homogeneous and the Moho is a sharp discontinuity, supercriticalPmP wavelets are large and isolated in the 100 km to 300 km distance range when compared to the preceding signals on the seismic traces. If the crust itself has numerous short reflectors and the Moho transition zone is thick or badly disrupted from past tectonic disturbances, thenPmP is often poorly defined and difficult to identify in the coda of earlier arriving signals. These signals are poorly correlated because the reflectors themselves are in general not only discontinuous but tend to be distributed at various depths within the crust. The effect of the vertical velocity gradient in the crust is to make the reflective field for downgoing waves much greater than for upgoing waves. The large variations in reflection coefficients wiht angle of incidence has the effect of making the coda generated by a reflective machanism distance dependent. The reflected signals are also contaminated with scattered signals from smaller scale heterogeneities which may be distributed more uniformly within the crust.In conventional seismic inversion methods applied to crustal refraction experiments, emphasis is usually placed on obtaining a velocity model of the subsurface structure. These models are relatively simple and are limited in the amount of complexity which can be uniquely inferred from the data. The main problem arises because of the difficulties in the identification of the origin of the signals which are themselves often incoherent from trace to trace.In this paper it is shown how the conventional record section may be complemented with a normal moveout corrected intensity section which emphasizes areas of large signal complexities. Data from this intensity section is then used as input to obtain a quantitative measurement of a complexity parameter. These measurements may be used to infer or compare differences in crustal heterogeneity from one region to another. The discussion is illustrated with both numerical modeling data as well as data from recent crustal experiments which were conducted over the Canadian Shield. 相似文献
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周返地区盐湖盆地发育复杂的盐韵律地层,储层密度可以对该区砂岩储层进行识别,但该区砂岩储层与非储层之间密度差异小,传统基于Aki-Richards近似公式的叠前密度反演结果精度低,无法满足对该区储层预测的要求。本文将精确Zoeppritz方程直接代入广义线性反演误差泛函,推导新的宽角度叠前反演公式,以克服近似公式对大角度叠前地震信号无法正确利用的缺点,进而提高反演结果的精度。对合成地震数据和工区实际数据的反演结果表明,该方法对密度反演结果的精度明显优于近似公式,满足周返地区盐湖盆地岩性油藏的高精度预测。 相似文献
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漳州盆地及其邻区地壳深部结构的探测与研究 总被引:5,自引:0,他引:5
漳州盆地及其邻区地处我国大陆东南沿海地震带中段。通过该地区高分辨率折射及宽角反射,折射地震探测剖面,获得了该区地壳几何结构与速度结构、地壳深浅部断裂的几何形态和构造关系等。结果表明,该区地壳分为上地壳和下地壳。上地壳的厚度为16.5~18.8km,下地壳厚度为12.0~13.0km。上地壳分为上下两部分。在上地壳下部有一个低速层,速度约为6.00km/s,低速层顶面深度为12.0km左右,厚度约为5.0km。下地壳也分为上下两部分。Moho界面的深度为29.0~31.8km。该区6条地壳浅部正断层大部分向地下延伸深度不超过4km,最大延伸深度达5km左右。据推测,浅部正断层下方有一条高倾角地壳深断裂带,该断裂带向下断至Moho面,向上断至上地壳下部低速层中。深浅部断裂构造不相连接。漳州盆地深浅部构造组合特征表明,九龙江断裂带是该区内一条特征明显、具有复杂深浅构造背景的深断裂带。这一深地震探测成果的获得,使得该地区深部资料解释的可靠性和探测精度比以往显著提高;对深浅部构造的组合可作统一解释,地壳的分层和结构特征更为确切和精细;首次发现上地壳的拉张性构造及铲式正断层组合特征,不仅有助于对漳州及其邻区地震危险性的综合判定,而且对深化东南沿海地震带深部动力学过程的认识具有重要意义。 相似文献
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IntroductionDuringtheMarchof1997,anactive-sourceseismicexperimentwasundertakenbyajointSino-GermanseismicprojecttoinvestigatethesubsurfacestructurebeneaththeDabieUHPMbeltwithintheframeworkofinternationalContinentalScientificDrillingProgramme(ICDP).ThetargetareaislocatedbetweenYuexiandQianshaninAnhuiProvince,andgeologicallyonthejunctureoftheDabieorogenicbeltandtheTanlufault(Figurel).Thisexperimentisparticularlydesignedsinthefieldcombinedwiththeinterestsofseismictomographyandwide-anglere… 相似文献
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Crustal structure of Gondwana- and Yangtze-typed blocks: An example by wide-angle seismic profile from Menglian to Malong in western Yunnan 总被引:10,自引:0,他引:10
ZHANG Zhongjie BAI Zhiming WANG Chunyong TENG Jiwen Lü Qingtian LI Jiliang SUN Shanxue & WANG Xinzheng . Institute of Geology Geophysics Chinese Academy of Sciences Beijing China . Institute of Geophysics Chinese Seismological Bureau Beijing China . Institute of Deposition Resource Chinese Academy of Geological Sciences Beijing China 《中国科学D辑(英文版)》2005,48(11):1828-1836
Ancient Tethyan vestige extends from Alps, Kaebaiqn Mountain and eastward through Turkey, IranAfghanistan, and the middle and north of Tibetan Plateau, then turns to western Yunnan and Sichuan, andfinally ends at Zhongnan Peninsula. The PaleoTethyan is supposed as one eastward opened Oceanand superposed by tectonic deformation in the latestage of the late Mesozoic to Paleocene of Cenozoicand covered by Mesozoic and Cenozoic deposits. The Sanjiang region in southwestern China is in the… 相似文献
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Exploration and Research of Deep Crustal Structures in the Zhangzhou Basin and Its Vicinity 总被引:1,自引:0,他引:1
Zhu Jinfang 《中国地震研究》2006,20(4):412-425
INTRODUCTIONThe Zhangzhou basinislocated onthe southeast coast of Fujian Province .Interms of geotectonicunits ,it lies in the east Fujian volcanic fault-depression zone between the Wuyi-Daiyun mountainupheaval zone and depression zone of Taiwan Straits of the south China block. In terms ofseismotectonics ,it islocatedinthe middle sectionof the southeasterncoastal seismic zone .In history,the area was influenced by repeated destructive earthquakes , and the seismic activity was closely… 相似文献