共查询到20条相似文献，搜索用时 109 毫秒
1.
大陆岩石圈有效弹性厚度与有关地球物理参数的关系--以泉州-黑水地学断面为例 总被引：1，自引：0，他引：1
大陆岩石圈有效弹性厚度(Te)是反映岩石圈综合强度的参数,它反映了岩石圈的整体特征。分析岩石圈有效样性厚度与反映深部地质特征的有关地球物理参数之间的关系,对研究控制Te的因素、各因素之间的关系以及探索大陆构造与大陆动力学等具有重要意义。泉州一黑水地学断面Te与地壳厚度、热岩石圈厚度、均衡重力异常、磁性构造层底面深度、上地幔低速层顶界面深度、上地幔低阻层顶面深度之间的关系研究表明：Te与大地热流关系密切的“热”地球物理参数磁性构造层底面深度、热岩石圈厚度相关性好;与地壳厚度有一定的相关性;上地幔低速层顶界面深度和上地幔低阻层顶面深度与大陆岩石圈Te相关性均较差。 相似文献
2.
长江中下游南京（宁）-芜湖（芜）段深部壳幔电性结构——宽频大地电磁测深研究 总被引：4，自引：1，他引：3
为了较全面、客观地认识南京(宁)-芜胡(芜)地区岩石圈深部结构,探讨岩石圈热结构和壳、幔物质状态等重要科学问题,为矿集区成矿作用和成矿规律的研究提供依据,我们完成了6条宽频大地电磁测深剖面。通过分析各剖面电性成像结果,讨论了研究区地壳-上地幔导电性的"拟三维"结构,发现测区普遍存在连续的下地壳-上地幔低阻层,仅在巢湖冲褶体断开。结合区域热流结果,我们认为下地壳-上地幔有较好的导电性,可能存在局部"熔融体"或"含水剪切断裂",其物质状态很可能是热的、软弱的。此外,我们通过物质状态和电性界面推断了上地幔隆起的位置和长江深断裂带的分布范围,认为长江断裂带不但存在,而且由多条北深南浅的断裂组成,较为复杂。 相似文献
3.
郯庐断裂带(郯城—庐江断裂带）中段地震活动强度大、频率高,是中国东部一条重要的地震活动带。强震沿该断裂带中段局部发生,弱震不均匀分布,一些部位为无震区。本文利用5条大地电磁测深剖面,对该断裂带中段地震孕育的深部背景进行了对比分析。结果表明,该断裂带切穿整个地壳,地壳电性结构显著不均一,但普遍出现陡立的低阻带与高阻带相间排列的现象,从而成为强烈的新构造活动带。该断裂带上3处≥Ms7级强震的地壳电性结构实例显示,带内上地壳中、下部出现刚性高阻层连接旁侧或两侧刚性高阻体时才会出现大的应力积累,从而成为强震发生必要的深部结构条件。而该断裂带弱震区显示全地壳尺度陡立软弱低阻带与刚性高阻带相间排列现象,其中的高阻带内只能积累有限应力而诱发弱震。该断裂带无震区上地壳出现了巨厚的异常软弱低阻层,成为极易蠕滑带,旁侧的刚性高阻体完全无法积累应力而诱发地震。上述实际对比分析表明,大型活动断裂带内上地壳的电性结构和流变学与地震活动性密切关联。 相似文献
4.
郯庐断裂带中段地震活动性与深部地壳电性结构关系的探讨 总被引：1，自引：0，他引：1
郯庐断裂带(郯城—庐江断裂带)中段地震活动强度大、频率高,是中国东部一条重要的地震活动带。强震沿该断裂带中段局部发生,弱震不均匀分布,一些部位为无震区。本文利用5条大地电磁测深剖面,对该断裂带中段地震孕育的深部背景进行了对比分析。结果表明,该断裂带切穿整个地壳,地壳电性结构显著不均一,但普遍出现陡立的低阻带与高阻带相间排列的现象,从而成为强烈的新构造活动带。该断裂带上3处≥Ms7级强震的地壳电性结构实例显示,带内上地壳中、下部出现刚性高阻层连接旁侧或两侧刚性高阻体时才会出现大的应力积累,从而成为强震发生必要的深部结构条件。而该断裂带弱震区显示全地壳尺度陡立软弱低阻带与刚性高阻带相间排列现象,其中的高阻带内只能积累有限应力而诱发弱震。该断裂带无震区上地壳出现了巨厚的异常软弱低阻层,成为极易蠕滑带,旁侧的刚性高阻体完全无法积累应力而诱发地震。上述实际对比分析表明,大型活动断裂带内上地壳的电性结构和流变学与地震活动性密切关联。 相似文献
5.
南北构造带天水、武都强震区地壳和上地幔顶部结构 总被引：1，自引：0，他引：1
利用两条相互垂直的高分辨地震折射/宽角反射剖面和相应的非纵观测的多个扇形剖面取得的人工地震资料, 研究天水和武都8级大震区的地壳和上地幔顶部结构和构造.二维剖面结果显示, 地壳沿垂向可分为上地壳和下地壳两大层.上地壳中部存在低速层, 层内介质速度比背景值低0.3~0.5km/s.莫霍面深度大约为46~48km.NE向的天水-武都剖面下地壳速度在横向上变化剧烈, NW向的成县-武山剖面, 在礼县以西, Moho面和C界面有被上涌物质改造过的迹象.三维速度成像显示, 在105°E附近, 从7至11km的深度范围内, 存在一条近NS向的断裂带, 在该带的两侧速度结构有明显的差异, 西侧为低速异常, 而东侧为高速异常, 这一近NS向的断裂带与二维剖面的下地壳深断裂在位置上很接近.该地区的几个8级大震均发生在105°E附近, 并且呈一近NS条带. 相似文献
6.
黑龙江五大连池火山群大地电磁探测和研究初步结果 总被引：2，自引：0，他引：2
对黑龙江五大连池火山群新近观测的7条大地电磁测深剖面资料进行了处理、解释和分析。研究表明,在地下约几百米深度至15～20 km左右,存在一个上宽下窄似铆钉状的高阻异常体,推测为固结过程中的火山岩浆体。该高阻体一直穿过地壳与上地幔连接,有向深处延伸的通道,并随着深度的加大,其电阻率逐渐减小。该火山群属于岩浆直接来自上地幔的火山类型,在地壳内没有明显的低阻岩浆囊存在。火山区的构造走向为近南北方向。 相似文献
7.
大陆浅源地震震源空间分布可以看作是一种地球物理特征,大量震源的空间位置数据可用来刻划大陆地壳结构。通过研究南北地震带南段震源的空间分布特征,发现研究区震源深度分布在横向上的疏密变化与地质构造特征相对应。剖面震源分布等密度图显示,中、下地壳不同深度广泛分布着多震层。多震层的分布与地壳低速、低阻层具有相关性,多震层一般位于低速、低阻层的上方。中地壳层次的低速、低阻层很可能是壳内滑脱层,是韧性下地壳与脆性上地壳发生拆离解耦的构造层次;下地壳低速、低阻层是部分熔融、含流体的韧性流变层;壳内多震层的构造属性应是上地壳硬的脆性层,容易发生突然破裂,产生地震。低速、低阻层是大陆板块内部上地壳脆性层构造过程的主控因素,包括对大陆内部浅源地震的控制;因此,在低速、低阻层之上往往形成多震层,越是活动性强的低速、低阻层,其上多震层震源密度越高。南北地震带南段不同层圈和块体之间的差异运动控制了其地壳层次的构造活动,包括大量地震的发生,其中,下地壳流层与上地壳脆性层的差异运动在中地壳层次发生剪切拆离是最重要的因素。 相似文献
8.
为了研究班公湖-怒江缝合带的壳幔电性结构及构造特征,并为其俯冲极性提供电性约束,对青藏高原中部申扎-双湖大地电磁测深剖面进行全面数据处理分析,获得了可靠的二维电性结构模型,研究表明:沿剖面上地壳分布的是规模不等的高阻体,底面埋深在10~25 km变化,高阻层之下发现由不连续的高导体构成的中下地壳高导层.通过对电性结构的分析,认为班公湖-怒江特提斯洋的俯冲消亡极性可能是双向的,随后拉萨-羌塘地体碰撞带处的上地壳高阻体发生拆沉,以上两次动力学事件可能共同作用于缝合带处的壳幔高导体,同时北拉萨地体的壳幔高导体还可能体现了构造作用、岩浆活动和成矿作用之间的关系. 相似文献
9.
青藏高原东南部地壳导电性结构与断裂构造特征——下察隅—昌都剖面大地电磁探测结果 总被引：10，自引：0，他引：10
根据2004年在青藏高原东南部完成的下察隅—昌都(1000线)宽频带大地电磁探测剖面数据研究高原东南部地壳导电性结构及断裂构造特征,这有助于推进印度与亚洲岩石圈碰撞、俯冲构造模式的研究。研究结果表明,沿剖面上地壳大范围分布的是规模不等的高阻体,电阻率大约在90～3000Ω.m,厚度由南向北增加,底界面的深度大约在5～30km变化。高阻层之下发现由不连续高导体构成的中地壳低阻层,其电阻率小于10Ω.m;其结构与青藏高原中、西部的壳幔高导体相似,但规模小得多,底面埋深也浅得多。沿剖面的上地壳存在多组规模不等、产状不同的横向电性梯度带或畸变带,它们反映了沿剖面地区地壳的断裂分布。通过与该区高精度重力资料对比,在重要的电性梯度带上,均存在布格重力低异常和负重力均衡异常。结合区域地质资料分析推断了嘉黎—然乌、班公—怒江和甲桑卡—赤布张错等主要断裂构造带的空间格局。 相似文献
10.
综合前人资料分析了川—滇构造带及其邻区地壳－上地幔速度结构与地震分布的关系。结果表明,川—滇构造带具有同青藏高原地壳－上地幔结构相似的某些特征;地震活动主要沿安宁河断裂带和小江断裂带分布。震源以永仁、渡口和会理三地所在区域最浅,向四周渐深 相似文献
11.
青藏高原是地球上最高大和最雄伟的年青隆起区。对于它的形成和演化机制,一直是国内外地质和地球物理学者注意的问题之一。 近十年来,人们认为青藏高原的形成是由于相距千里之遥的印度板块向北漂移并与欧亚板块碰撞的结果。然而,根据作者对喀喇昆仑和喜马拉雅等地的野外考察及其深部地球物理资料的研究,提出青藏高原原来是一个统一的前震旦纪陆壳区,后经震旦纪以来多次的拉开和挤压碰撞而形成的新观点。这种拉开和挤压的运动方式,是深部鳗隆和慢拗的分异作用引起的。 相似文献
12.
长江中下游地区经历了多期次的地质构造演化具有丰富的矿产资源,对重要矿集区及其邻区的深部电性结构进行研究具有重要意义。通过对穿过安庆—贵池矿集区的一条宽频带大地电磁测深长剖面数据进行分频段以及分区反演,构建了覆盖大别造山带至下扬子地块东缘的二维电性结构模型。发现矿集区的深部电性结构与邻区的构造单元具有显著差异,大别造山带和江南隆起带与浙赣凹陷之间的地壳整体表现为高阻特征,而下扬子坳陷和江南隆起带之间存在岩石圈上地幔尺度的高导电异常体并且与地壳浅部的高导体相连。安庆—贵池矿集区的成矿机制主要为燕山期陆内俯冲以及早白垩时期的伸展作用,矿集区下地壳加厚、拆沉和上地壳丰富的断裂系统起到了重要的控矿作用。 相似文献
13.
Lithospheric structure and dynamic processes of the Tianshan orogenic belt and the Junggar basin 总被引：8，自引：0，他引：8
Located at the center of the Eurasian continent and accommodating as much as 44% of the present crustal shortening between India and Siberia, the Tianshan orogenic belt (TOB) is one of the youngest (<20 Ma) and highest (elevation>7000 m) orogenic belts in the world. It provides a natural laboratory for examining the processes of intracontinental deformation. In recent years, wide angle seismic reflection/refraction profiling and magnetotelluric sounding surveys have been carried out along a geoscience transect which extends northeastward from Xayar at the northern margin of the Tarim basin (TB), through the Tianshan orogenic belt and the Junggar basin (JB), to Burjing at the southern piedmont of the Altay Mountain. We have also obtained the 2D density structure of the crust and upper mantle of this area by using the Bouguer anomaly data of Northwestern Xinjiang. With these surveys, we attempt to image the 2D velocity and the 2D electric structure of the crust and upper mantle beneath the Tianshan orogenic belt and the Junggar basin. In order to obtain the small-scale structure of the crust–mantle transitional zone of the study area, the wavelet transform method is applied to the seismic wide angle reflection/refraction data. Combining our survey results with heat flow and other geological data, we propose a model that interprets the deep processes beneath the Tianshan orogenic belt and the Junggar basin.Located between the Tarim basin and the Junggar basin, the Tianshan orogenic belt is a block with relatively low velocity, low density, and partially high resistivity. It is tectonically a shortening zone under lateral compression. A detachment exists in the upper crust at the northern margin of the Tarim basin. Its lower part of the upper crust intruded into the lower part of the upper and the middle crust of the Tianshan, near the Korla fault; its middle crust intruded into the lower crust of the Tianshan; and its lower crust and lithospheric mantle subducted into the upper mantle of the Tianshan. In these processes, the mass of the lower crust of the Tarim basin was carried down to the upper mantle beneath the Tianshan, forming a 20-km-thick complex crust–mantle transitional zone composed of seven thin layers with a lower than average velocity. The thrusting and folding of the sedimentary cover, the intrusive layer in the upper and middle crust, and the mass added by the subduction of the Tarim basin into the upper mantle of the Tianshan are probably responsible for the crustal thickening of the Tianshan. Due to the important mass deficiency in the crust and the upper mantle of the Tianshan, buoyancy must occur and lead to rapid ascent of the Tianshan.The episodic tectonic uplift of the Tianshan and tectonic subsidence of the Junggar basin are closely related to the evolution of the Paleozoic, Mesozoic, and Cenozoic Tethys. 相似文献
14.
秦岭洛阳—伊川—十堰—秭归地学断面大陆岩石圈的岩石学模型 总被引：4，自引：0，他引：4
根据该地学断面Ｖｐ结构模型，造山带中基性火成岩、金伯利岩和花岗岩中的深源包体资料，以及火成岩和变质岩，特别是超高压变质岩和超基性岩的分布和组成所揭示的壳幔深部组成的信息，结合与相对应的岩石实验Ｖｐ数据的对比，建立了秦岭洛阳－伊川－十堰－秭归地学断面及邻区的岩石圈组成的岩石学模型。这一岩石学模型表明，华北与扬子克拉通，南北秦岭造山带与其克拉通的过渡带岩石圈的岩石学模型各不相同。华北克拉通下地壳是以麻粒岩相中酸性片麻岩和紫苏花岗岩为主，同时含有基性麻粒岩，而扬子克拉通的下地壳是以角闪岩相－麻粒岩相酸性片麻岩和ＴＴＧ为主体，广泛存在基性火成岩层。南北秦岭造山带的中下地壳各自继承了扬子和华北克拉通的中下地壳的特点，但已被强烈改造；南北秦岭造山带上地幔组成差异性较大，北秦岭上地幔上部以榴辉岩及榴闪岩为主，而南秦岭以蛇纹石化橄榄岩为主体，各单元１００ｋｍ以下的地幔都是一样的，都是石榴石二辉橄榄岩组成。因此，秦岭造山带是一个具有近３０亿年历史的由不同大陆块体拼合组成的，不具简单的岩石圈分层结构样式。 相似文献
15.
Magnetotelluric soundings have been carried out across the archaean terrain of Singhbhum granite batholith from Bangriposhi
to Keonjhar for a distance of about 100 km. One-dimensional inversion models reveal that the depth of the moho varied between
23 and 40 km. The depth of the lithosphere asthenosphere boundary varied from 58 to 76 km. A zone of higher electrical conductivity
detected at the base of the lower crust just above the moho is present along the entire profile. Signals within the range
of 0.25 to 600 seconds, which crossed the coherency threshold of 0.8 to 0.9, could be stacked. Resistivity ranges of the crust
mantle silicates below Singhbhum granite batholith vary over a wide range. Resistivity ranges are (i) 30,000–80,000 ohm for
Singhbhum granite phase II, (ii) 2,000 to 9,000 ohm-m for Singhbhum granite phase III, (iii) 250 to 2,200 ohm-m for lower
crust (iv) 3,000 to 47,000 ohm for the upper mantle and (v) 200 to 2300 ohm-m for the asthenosphere. Sharp break in electrical
resistivity at the (i) upper crust-lower crust (ii) lower crust upper mantle and (iii) lithosphere-asthenosphere boundary
is obtained along the entire profile. Signals could see up to 100 km below the granite batholith. Singhbhum granite phase
II and III could be demarcated on the basis of resistivity. Low resistive zones in the lower crust and upper mantle might
have formed due to (i) water (ii) combined effect of water and carbon and (iii) high temperature and partial melt. 相似文献
16.
从闪长质岩石包体角度探讨太行山——燕山造山带壳幔成矿作用 总被引：5，自引：3，他引：5
文中首次从闪长质岩包体的角度讨论了上地幔，中，下地壳成分及岩浆演化过程对成矿作用的影响，指出太行山－燕山造山带成矿作用及其区域成矿规律明显受到壳幔成矿体系的制 相似文献
17.
济阳坳陷地幔热流和深部温度 总被引：8，自引：2，他引：6
济阳坳陷深部地热状况对于分析岩石圈深部结构特征、探索该盆地形成和演化的地球动力学过程具有重要意义.依据济阳坳陷最新的钻探资料和深部地球物理探测结果, 按沉积盖层、上、中、下地壳4层结构, 建立了分别代表该区凹陷部位和凸起及斜坡带上的2种地壳结构模型.通过多道能谱分析, 测试了区内4 3块岩心样品的放射性元素U、Th、40K含量, 统计得出了济阳坳陷沉积盖层的平均生热率为(1.40±0.26) μW/m3.在研究大地热流分布的基础上, 结合济阳坳陷地壳各岩层放射性生热率, 采用“剥层”法, 从地表开始, 由浅到深逐步扣除各层段所提供的热量, 得到了济阳坳陷的地幔热流.并且采用相似的方法, 利用一维稳态热传导方程, 分析了地壳上地幔顶部的温度状况.结果表明, 济阳坳陷的地幔热流约为38.4~39.2 mW/m2, 占整个地表总热流量的5 8%;地幔顶部温度约为602~636℃.与世界上其他各类地质构造单元相比, 济阳坳陷无论是地幔热流值或其与地表热流之比值都是比较高的, 其深部地热状态具有介于稳定地区和构造活动区之间的特点. 相似文献
18.
Magnetotelluric soundings (MTS) were conducted in a broad frequency range of 10 kHz to 0.001 Hz at a total of fifty-seven sounding sites of the profile spaced 5 km apart and intersecting the northern Sikhote-Alin across the strike. The analysis of the obtained magnetotelluric parameters has been made which shows three-dimensional geoelectric nonuniformities in the lower crust and upper mantle. The MTS curve interpretation was carried out in the framework of a three-dimensional model. As a result of the inverse problem solution, the geoelectric section has been constructed down to 150 km depth. The section distinguishes the crust with a resistivity higher than 1000 Ohm m and variable thickness between 30 and 40 km which is consistent with deep seismic sounding (DSS) data. The crust is subdivided into four blocks by deep faults, and each block is characterized by a set of parameters. The data support the existence of the Vostochny deep fault in the study area, whereas, on the contrary, the deep roots for the Central Sikhote-Alin fault have not been established. The upper mantle structure is nonuniform; three low-resistivity zones are identified that coincide with the boundaries of crustal blocks. In the revealed zones, an increase in the resistivity is noted from the continent to the Tatar Strait coast. A high-resistivity layer of 300–400 Ohm m was observed in the coastal area, which was steeply dipping from the crustal base down to 120 km depth and extended beneath the continent. Based on a set of geological and geophysical data, the ancient subducting plate is suggested in this area, and the evolutionary model of the region is proposed starting from the Late Cretaceous. The most probable mechanism of conductivity within the upper mantle is determined from petrological and petrophysical data. The low resistivity values are linked to dry peridotite mantle melting. 相似文献
19.
《Gondwana Research》2010,17(3-4):563-571
We carried out magnetotelluric (MT) surveys in central northeastern Japan. Two-dimensional resistivity profiles along three survey lines show similar features each other. By comparing the resistivity distribution to the distribution of seismic velocities, we inferred the distribution and flow of crustal fluids. Three fluid flow paths were detected based on the distribution of regions of low resistivity. The first path ascends from the top of the upper mantle, passes through the lower crust, and reaches the surface, forming a fluid chamber within the lower or middle crust. This path is related to the volcanic activity in the backbone range. The second path rises from the first fluid chamber and has produced small fluid reservoirs on both sides of the backbone range. These small reservoirs are considered to be related to the seismicity of the region. The third path is located to the east of the volcanic front and represents another fluid flow path from the uppermost mantle to the lower crust that may have formed a small fluid reservoir to the east of the volcanic front. 相似文献