共查询到19条相似文献，搜索用时 109 毫秒
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大地电磁测深结果表明,唐山地区深部电性中存在壳内高导层和上地幔高导层,其分别埋深为20公里和100公里左右,均显示为南浅北深。资料对比表明唐山、宁河地震都发生在两个高导层埋深变化梯度带上,其震源深度都不超过壳内高导层的埋深。此外,在该区南部发现埋深约45公里高导层,我们认为有可能为上地幔中间高导层 相似文献
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本文是壳慢流体演化及地震成因系列论文的第1篇．本系列由3篇论文组成，第2篇为壳内高导层成因，高温高压下卤水物态及其电导率；第3篇为壳内流体演化及地震成因．这3篇论文分别从宏观、微观和动态变化三方面，探讨了地下流体与地震的关系．
本文根据我国大地电磁测深(MT)工作者近20年的探测成果，编绘了中国大陆壳内和上地幔高导层的分布埋深图，分析了中国大陆电性结构的分区特征，探讨了上地幔高导层的成因以及壳内高导层的特征，最后总结了中国大陆不同构造区的地震孕育规律． 相似文献
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辽宁义县—内蒙古东乌珠穆沁旗剖面深部电性研究 总被引：5，自引：0，他引：5
本文给出了沿辽宁义县—内蒙古东乌珠穆沁旗大地电磁测深剖面的电性结构。研究结果表明,沿该剖面壳内和上地幔高导层的埋藏深度与温度场有着良好的对应关系,即壳内、上地幔高导层埋深愈浅,其热流值愈高,反之就越低。大地电磁测深结果还表明,辽西隆起区继承了辽南地区上地幔高导层起伏形态。本文还从电性结构特征探讨了西拉木伦河断裂带可能是西伯利亚板块和中国板块的缝合线 相似文献
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本文从部分地球物理资料出发,初步探讨了中国南北地震带北段(贺兰山—六盘山地震带)、中段(天水—武都、文县—川西北地震带)地壳和上地慢的结构特征。 根据对有关资料的分析研究,初步得出中国南北地震带北段、中段深部地震环境的主要特点: 地震带下部的上地幔顶面呈带状隆起:银川地堑地区上地幔顶面带状隆起的轴向呈北北东向;西吉、海原、固原地区呈北西向;天水—武都地区呈近南北向。 强烈地震的断层走向、震中迁移方向与软流圈顶面等深线轴向方向一致。 强烈地震往往发生在深部构造与浅部构造在深部的交汇区,如天水、武都地区。 强烈地震与壳内高导层和上地幔高导层的局部隆起和拗陷有关。 进而尝试性的分析了深部环境与地震孕育发生的关系。最后文章讨论了深部地震环境对中长期地震预报和地震成因研究的意义 相似文献
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内蒙古东乌珠穆沁旗至辽宁东沟地学断面综合地球物理特征 总被引：2，自引：1，他引：2
综合地球物理探测与研究是地学断面的重要内容和基本依据,本断面的综合地球物理研究表明:这里的地壳可分为上、中、下三层,在某些部位中层地壳可进一步分为两层,其上层在断面东南端的辽河断陷东侧及燕山台褶带的义县、朝阳地区呈现为低速层;地壳厚度在断面东南端薄,为31—35km,而在西北端厚,达38—40km;辽河裂谷东侧存在壳内高导层,整个断面上地幔高导层发育,在辽河断陷及朝阳、义县地区反映为上地幔隆起区,在西拉木伦河一带出现落差达50km左右的台阶;确认析木断裂、郯—庐断裂北段、朝阳—北票断裂、赤峰—开原断裂和西拉木伦河等断裂为壳幔深断裂;发现海城地区、朝阳—北票地区及西拉木伦河地区为地壳与上地幔结构异常区,这里也正是地震较活跃的地区。 相似文献
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根据大地电磁测深调查结果，编制了中国大陆３０，９０，１５０ｋｍ三个深度的电阻率图以及壳内低阻层和上地幔低阻层的顶面深度图。在９０ｋｍ深度的电阻率图上发现了一个自松辽盆地直到扬子地台西南缘的北东－南西向巨大低阻异常带．１５０ｋｍ深度的电阻率图上显示出在低阻的背景上镶嵌着一些高阻块体．中国大陆的壳内低阻层深度国基本上反映了地温场的特征，壳内低阻层上隆区基本上对应于高地温区．中国大陆的上地幔低阻层深度变化大．最浅处仅５０－６０ｋｍ，大多位于构造活动地区；最深处达２００ｋｍ以上，大部分对应于稳定地区．中国大陆的上地幔低阻层平均深度为１００－１２０ｋｍ，东部浅，西部深。 相似文献
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利用环渤海地区的天然地震P波到时资料,采用纬度和经度方向分别为05°×06°的网格划分,反演了该地区地壳上地幔的三维P波速度结构.初步结果表明,环渤海地区地壳上地幔的速度结构具有明显的横向不均匀性：京津唐地区地壳中上部的速度异常反映了浅表层的地质构造特征,造山带和隆起区对应于高速异常,坳陷区和沉积盆地对应于低速异常;地壳下部出现大规模的低速异常与华北地区广泛存在的高导层相对应,估计与壳内的滑脱层和局部熔融、岩浆活动有关;莫霍面附近的速度异常反映了地壳厚度的变化及壳幔边界附近热状态的差异;上地幔顶部大范围的低速异常可能是上地幔软流层热物质大规模上涌所致. 相似文献
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根据四川大足-福建泉州剖面的大地电磁测深结果,划分了低阻的中新生界、高阻的三叠系-古生界以及相对低阻的浅变质的元古界板溪群等;了解了一些岩体的底界深度,推断沅麻盆地5 km以下出现岩脉群. 武陵山重力梯度带附近,中下地壳至上地幔岩石层有很高的电阻率,它和梯度带的形成有关.华南褶皱系普遍存在壳内高导层,它和爆破地震所反映的壳内低速层的位置相近. 深部电性证明,华蓥山断裂带、茶陵断裂带和福安-南靖断裂带等是深、大断裂带. 上地幔岩石层在横向上具有不同的电阻率.软流层深度自西向东由120-150kin变化到76km,衡阳以东最深可达240km. 由软流层变化及断裂分布,认为扬子准地台和华南褶皱系两大构造单元的分界位于茶陵-永兴断裂附近. 相似文献
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ELECTRICAL STRUCTURE OF UPPER CRUST IN THE SOURCE REGION OF JINGGU YUNNAN MS6.6 EARTHQUAKE AND THE SEISMOGENIC ENVIRONMENT 
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下载免费PDF全文 The October 7, 2014 MS6.6 earthquake in southwest of Jinggu in the southwestern Yunnan Province occurred as the result of shallow strike-slip faulting within the crust of the Eurasia plate in the broad plate boundary region between the India and Eurasia plates. The strike of fault plane is 140°, and the aftershock distribution shows that the rupture plane is also NNW-trending. Tectonics of the region are controlled by the convergence of the India plate with Eurasia, which has driven the uplift of the Himalayas to the west of this earthquake, and has caused the formation of numerous intraplate continental transform structures in the surrounding region. The pattern of elastic-wave radiation from the earthquake is consistent with the shock occurring either as the result of right-lateral faulting on a northwest-trending fault or as the result of left-lateral faulting on a northeast trending fault. Faults of both types have been mapped in southwestern Yunnan, and it is unclear at this time which type of fault hosted this event. Magnetotelluric survey line is across Jinggu earthquake zone. The advanced data processing and analysis technology of MT is employed and the quantitative data from field surveys are analyzed to acquire the reliable electrical model. The MT data are inverted using nonlinear conjugate gradient (NLCG) inversion algorithm. At last, the interpretation of the electrical model is performed considering the geology and the other geophysical data. Based on the final inversion model of the target profile, it is found that:(1) Electrical structure of the source region can be divided into four layers:The surface is relatively low resistivity layer(0~5km), consisting mainly of Mesozoic and Cenozoic Basin sedimentary rocks, the value of resistivity is 100Ω·m; The high resistivity layer(5~10km) in upper crust mainly consists of Proterozoic metamorphic rocks, with resistivity higher than 1 000Ω·m; there are the upper crust high-conductivity layer(15~25km) and crust-mantle transition zone(blow 25km); (2) The focal depth of the Jinggu earthquake is about 10km, which locates in the interface between high resistivity layer and high-conductivity layer; (3) Most of the focal depths of the aftershocks are in the range of 5km and 10km, and the two depths(5km & 10km) are corresponding to the resistivity gradient belt. 相似文献
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在华北地区大地电磁测深工作的基础上,本文对北京——柏各庄剖面上的大地电磁观测资料,使用连续介质反演方法进行反演解释,获得了电性结构的最新结果。对构制的可接受地电模型的评价表明,本剖面内地壳中部普遍存在高导电带,上地幔内高导电带的深度变化较大,电阻率为1m的等值线深度,在沧县隆起为70多km,其西侧和东侧分别在60km和50km左右。上地幔高导电带的电阻率值由西而东有减小的趋势。这些结果与表层构造的对应关系说明,上地幔软流圈及地热场的横向不均一性,对地壳内部发生的构造运动有重要意义。 相似文献
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STUDY ON THE ELECTRICAL STRUCTURE OF THE ANQIU AND JUXIAN ELECTROMAGNETIC STATIONS IN THE TANLU FAULT ZONE 下载免费PDF全文
下载免费PDF全文 ZHANG Ji-hong ZHAO Guo-ze DONG Ze-yi WANG Li-feng HAN Bing WANG Qing-lin TANG Ting-mei WANF Mei 《地震地质》2019,41(5):1239-1253
The Yishu fault zone is one of the branch faults of the Tanlu fault zone in its central part. Moderate and strong earthquakes occurred in the Yishu fault zone repeatedly. Due to its complex structure, the Yishu fault zone attracts much attention from earthquake researches. The Anqiu and Juxian electromagnetic stations in Shandong Province locate near the Anqiu-Juxian Fault and Changyi-Dadian Fault, which are branches of the Yishu fault zone, respectively. Geoelectric field and geomagnetic field observation were carried out in these two stations. The Wudi electromagnetic station is in the west of Tanlu fault zone in the Jidong-Bohai block and 230km from Anqiu electromagnetic station. This paper firstly describes the crustal structure near the electromagnetic stations by using magnetotelluric(MT)method. By processing the data carefully, we obtain the MT data in good quality near the stations. The MT data of each electromagnetic station and its nearby area suggests that the electrical structure and geological structure of the station are comparable. This paper applied 1-D and 2-D inversion for MT data and obtained the crustal electrical structure model beneath the Anqiu and Juxian seismic station. The shallow electrical structure from the MT method was compared with the results of symmetrical quadrupole electrical sounding. The model suggests that the electrical structure beneath the Anqiu and Juxian electromagnetic stations is complex and shows the feature of block boundary. The Wudi electromagnetic station is located inside a basin, the crustal structure shows layered feature typical for the stable blocks. Beneath the Anqiu electromagnetic station, there is a 1km-thick relative low resistivity layer in the shallow crust and a high resistivity body beneath it with a depth of 13km. There is a high resistivity structure in the crust beneath the Juxian electromagnetic station. The crustal structures are divided into two different parts by Anqiu-Juxian Fault and Changyi-Dadian Fault, respectively. More conductive layers appear to the west of the two faults. Plenty of fluid possibly exists within the conductive body to the west of Changyi-Dadian Fault, which plays important role in the earthquake generation. There is a relative low resistivity layer in the crust within 1~2km beneath the Wudi electromagnetic station. Beneath the relatively low resistivity layer, a relatively high resistivity layer extends to a depth of around 15km, and the resistivity value decreases with the increase of depth. The electrical resistivity model suggests the seismic activity of the Yishu fault zone around the Anqiu and Juxian electromagnetic stations should be taken into account seriously, and monitoring and research on it need to be strengthened. The results of this paper provide a certain reference value for the crustal structure research to similar stations. 相似文献
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利用面波层析成像和远震接收函数方法对长白山地区的地壳上地幔速度结构进行了研究。结果表明:长白山火山区附近存在岩石圈减薄、上地幔软流圈增厚以及上地幔S波速度降低等与上地幔高温物质有关的现象,它表明长白山的岩浆系统一直延伸到上地幔软流圈范围。天池火山区地壳内部存在明显的S波低速层,在离天池火山口较近的WQD台附近,低速层顶部埋深约8km,厚度近20km,S波最小速度约2.2km/s。在距离天池火山北部50km的EDO台地壳中没有明显的低速层。火山区S波速度结构总体表现出距离天池越近,地壳的V_P/V_S越大,低速层的厚度和幅度增加的特征,表明天池火山口附近地壳内部存在高温物质或岩浆囊。CBS台站不同方位的接收函数及反演结果表明,地表低速层厚度以及莫霍面深度存在随方位的变化。地表低速层在南部方向明显较厚,莫霍面深度在南部天池火山口方向存在小幅度抬升。CBS台站附近特殊的近地表速度结构可能是该台站记录的火山地震波形主频较低的主要因素。天池火山口附近莫霍面的小幅度抬升意味着存在与火山作用有关的壳幔物质交换通道 相似文献
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A. Ádám L.L. Vanyan D.A. Varlamov I.V. Yegorov A.P. Shilovski P.P. Shilovski 《Physics of the Earth and Planetary Interiors》1982,28(3):251-260
On the basis of numerical modelling and statistical investigations of the horizontal electrical inhomogeneities (narrow fractures, change of conductance of the surface sediments) ρmin magnetotelluric (MT)-sounding curves were found to be less distorted and, therefore, they can be used for the determination of deep conducting formations in the crust and upper mantle.Carefully selected MT curves indicate the crustal conductive layer at depths of 7–13 km and the conductive asthenosphere between 50 and 80 km.The relatively shallow position of the asthenosphere corresponds to the high heat flow (q > 80 mWm?1) in the Pannonian basin according to the empirical relation derived by Ádám (1978). 相似文献
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本文对一条布设在滇西盈江—龙陵地区的大地电磁剖面(苏典—中山剖面)数据进行了精细处理和二维反演解释,得到了测区较高置信度的二维电性结构.该电性模型纵向上表现为高阻-低阻-高阻的"三明治"式岩石圈电性结构,上地壳为平均厚度约为10km的高阻地层,在约6～16km地壳深度范围发育有电阻率为几欧姆米的显著高导层,下地壳底部和上地幔顶部表现为电性较为均匀的相对高阻层.横向上自西向东划分出以大盈江断裂带、龙陵—瑞丽断裂带为限的3个主要构造区域.壳内分布的高导层沿剖面表现出一定的横向不均匀性,其在龙陵—瑞丽断裂带下方消失,在该处形成了腾冲地块和保山地块的电性构造边界.电性结构表明,大盈江断裂附近高导层顶界面浅,两侧高阻体厚度小,因此难以形成较大规模的相互作用,致其附近浅震源、小震级的地震活跃;龙陵—瑞丽断裂两侧的高阻体较厚,易积累较大的应力,具有大震的深部孕震环境,故其附近发生过多次7级以上强震. 相似文献
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由50余个测点的大地电磁测深资料,讨论了该区的地壳-上地幔电性横向变化特征。按照上地幔第一低阻层顶面埋深,将测区划分为四类地区:浅埋深(55-90公里)、中浅埋深(90-110公里)、中深埋深(110-160公里)和深埋深(160-250公里)。讨论了本区六次大震例的深部电性背景。指出了上地幔顶部的梯度带地区、地壳内电性横向变化剧烈的地区和地壳内存在局部特殊增厚的低阻层地区将可以作为潜在震源区的深部电性判据之一 相似文献