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IntroductionAccording to the division of Neo-tectonically active blocks northeastern Qinghai-Xizang (abbreviated as QX thereafter) plateau is a juncture region where 3 intra-continental subplates, the Qinghai-Xizang, Xinjiang and North China subplate, meet with each other (DING, 1991). The subplates generally consist of blocks. Specifically, around the Yinchuan-Haiyuan (quasi-trijuncture( (TIAN, DING, 1998), where the 3 subplates meet, to the south locates the Gansu-Qinghai (GQ) blo… 相似文献
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喜马拉雅构造带于新生代时期经历了两代受力条件截然不同的形变。早期造山挤压形变与造山后的引张形变、青藏高原和高喜马拉雅的大幅度抬升。大致低喜马拉雅范围即青藏高原南缘，现今构造活动与青藏高原和高喜马拉雅块断抬升相辅相成。流行的板块聚合动力学模式，即使早新生代发生过，晚新生代以来已经灯熄。东亚大陆现代形变与地震活动的驱动力不可能源于青藏高原南缘被动挤压，而是取决于与高原隆起相关的深部主动动力学过程 相似文献
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青藏高原东缘的地壳结构是两种主流青藏高原隆升模式争辩的焦点之一.中下地壳流曾经被认为是高原东缘隆升的主要构造驱动力,但是中上地壳之间低阻低速层的发现及其与2008 MS8.0汶川地震良好的对应关系表明,高原东缘具有向东刚性挤出的可能性.然而大部分关于龙门山断裂的数值模拟仍建立在下地壳流的基础上,仅将低阻低速层作为断裂的延续或是弱化地壳物性参数的软弱层,而非能够控制块体滑动的"解耦层",也没有考虑到刚性块体变形中的断裂相互作用.本文建立了包含相互平行的龙门山断裂与龙日坝断裂的刚性上地壳模型,用极薄的低阻低速层作为块体滑动的解耦带,采用速率相关的非线性摩擦接触有限元方法,基于R最小策略控制时间步长,计算了在仅有侧向挤压力作用下,低阻低速层对青藏高原东缘的刚性块体变形和断裂活动的作用.计算结果显示,低阻低速层控制了刚性块体的垂直变形和水平变形分布特征.在侧向挤压力的持续作用下,在低阻低速层控制下的巴颜喀拉块体能够快速隆升,而缺乏低阻低速层的四川盆地隆升速度和隆升量均极小,隆升差异集中在龙门山断裂附近,使其发生应力积累乃至破裂.龙日坝断裂被两侧的刚性次级块体挟持着一起向南东方向运动,但该断裂的走滑运动分解了绝大部分施加在块体边界上的走滑量,使得相邻的龙门山次级块体的走滑分量遽然减少,也使得龙门山断裂表现出以逆冲为主,兼有少量走滑的运动性质.本文所得的这些计算结果显示了在缺乏中下地壳流,仅在低阻低速层解耦下刚性块体隆升过程及相关断裂活动,提供了青藏高原东缘刚性块体挤出的可行性,为青藏高原东缘隆升机制的研究讨论提供了重要依据. 相似文献
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Zhong Jia-you 《地震地质》1988,10(3):78
This paper deals with the uplift mechanism and the uplift form of Qinghai-Xizang (Tibet) plateau and the deformation regularity of its surrounding region caused by this uplifting. It is shown that the insertion of Indian plate with the wedge-like frontal margin beneath Qinghai-Xizang plateau made the plateau compressed and uplifted; at same time along several pre-existing large faults, striking NE and NW, the strike-slip movement took place. It is of great significance to study Asian 相似文献
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Present-day tectonic movement in the northeastern margin of the Qinghai-Xizang (Tibetan) plateau as revealed by earthquake activity 总被引：2，自引：0，他引：2
Characteristics of present-day tectonic movement in the northeastern margin of Qinghai-Xizang plateau (Tibetan) are studied
based on earthquake data. Evidence of earthquake activity shows that junctures between blocks in this area consist of complicated
deformation zones. Between the Gansu-Qinghai block and Alxa block there is a broad compressive deformation zone, which turns
essentially to be a network-like deformation region to the southeast. The Liupanshan region, where the Gansu-Qinghai block
contacts the Ordos block, is suffering from NE-SW compressive deformation. Junction zone between the Ordos and Alxa block
is a shear zone with sections of variable trend. The northwestern and southeastern marginal region of the Ordos is under NNW-SSE
extension. The above characteristics of present-day tectonic deformation of the northeastern Qinghai-Xizang plateau may be
attributed to the northeastward squeezing of the plateau and the resistance of the Ordos block, as well as the southeastward
extrusion of the plateau materials.
Foundation item: State Natural Science Foundation of China (49732090) and the Development Program on National Key Basic Researches under
the Project Mechanism and Prediction of Continental Strong Earthquakes (95-13-02-05).
Contribution No. 00FE2003, Institute of Geophysics, China Seismological Bureau. 相似文献
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DONG-NING ZHANG 《地震学报(英文版)》1999,12(2):148-154
The numerical dynamic model of Chinese mainland lithosphere's stress and strain field was constructed with elasto-viscous creep constitutive relation. The most recent data of the stress field of Chinese mainland and the horizontal movement velocity of the crust blocks were used as constraint conditions. The values of the boundary force were computed by trial-and-error method. The effect of the Qinghai-Xizang Plateau's excess potential energy to the movement of Chinese mainland was studied also in this model. The results of the numerical computing show that, recent rapid raising of the Qinghai-Xizang Plateau and the generation of normal faults in the southern part of the plateau resulted from the convergence of Indian Plate to the Eurasian Plate, and also from the rapid convective thinning of the lower lithosphere. Horizontal extension of the Qinghai-Xizang Plateau is the main dynamic factor to form the present tectonic framework of the Chinese mainland. The compressive loads on the eastern boundary of the model were mainly applied by the subduction of the Pacific Plate. The compression from the Philippine Plate maybe slight. 相似文献
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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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在青藏高原的运动变形过程中，断层活动起着至关重要的作用.本文利用有限元数值模拟的方法，分别计算了在GPS做边界约束下青藏高原及周边区域的连续体模型和含断层的不连续体模型的运动状态和应力场分布.从连续性模型和非连续体模型的差异发现，断层存在与否很大程度上影响了青藏高原现代运动场的分布.主要体现在，断层的滑移运动（1）增加了青藏高原东西两侧的拉张趋势；（2）加大了青藏高原物质东移的速度；（3）改变了塔里木和柴达木盆地的运动状态.模拟结果显示，非连续模型的运动场分布与GPS观测结果吻合程度大大高于连续体模型结果，表明断层活动在青藏高原的运动学和动力学过程中起着重要的作用，在研究青藏高原的动力学机制中，必须考虑断层作用的影响. 相似文献
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本文对位于青藏高原东缘川滇构造区的贡山一绥江大地电磁测深(MT)剖面数据进行反演,获得沿剖面的深部电性结构,为研究喜马拉雅东构造结、川滇菱形地块与华南地块的构造变形特征、壳幔耦合关系、地块间接触关系以及相互作用等问题,提供电性结构的依据.研究发现:(1)电性结构揭示澜沧江断裂带和小金河断裂带为深大断裂带,控制着研究区的深部结构特征和形变机制;(2)澜沧江断裂带和金沙江断裂带之间的高阻体,可能是扬子古地块的残留部分;小金河断裂带和安宁河断裂带之间的高阻体,则是峨眉山大火山省喷发形成的冕宁一越西杂岩带;(3)在滇西地块、川滇地块和大凉山地块均存在低阻层,它们的介质属性有所不同,滇西地块下的低阻层"疑似"高热状态的岩浆囊,主要由缅甸弧向东俯冲运动引起的,中上地壳的高热状态使地块的活动性增强;川滇地块内部的壳内低阻层的成因为:理塘断裂带和小金河断裂带之间的地表低阻层由破碎带充水所致,而金沙江断裂带和理塘断裂带之间的中地壳低阻层可能是由局部熔融物质或含盐流体导致的,其为壳内物质运移的通道.从而在地下物质发生大规模走滑运动的过程中起到引导作用;川滇地块东部和大凉山地块西部的壳内低阻层可能与地慢物质的上涌有关;马边断裂带附近的低阻体可能与破碎带变宽和破碎带内的流体有关. 相似文献
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现今地壳变形数据显示横跨龙门山断裂带的地壳缩短速率低于3 mm·a-1,如此小的地壳缩短速率与龙门山断裂带附近的长期地质造山（平均高程约4.5 km）形成强烈对比.我们构建并使用了一个二维平面应变黏弹塑性有限元模型来模拟龙门山断裂带的地震循环位移变化,从而探讨了短期变形与长期变形之间的关系.模型模拟了地震循环的各个阶段（震间加载期、同震瞬间和震后黏性松弛调整期）以及多个地震循环（万年尺度）的地表变形,揭示了变形在地震循环中是如何累积、释放、调整以及最终形成永久变形导致了造山.模拟结果显示,岩石圈流变结构以及断层几何形态均对地震循环的地表位移变化有着显著的影响.经过多个地震循环,青藏高原东缘整体产生水平缩短与增厚抬升,而四川盆地基本保持稳定,区域的水平缩短主要由断层位错及青藏东缘的缩短抬升来调解,造成了青藏东部与川西盆地的差异抬升.研究结果将地震循环时间尺度的短期变形与长期地质造山联系起来,帮助我们理解青藏高原东部的隆升机制. 相似文献
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从新构造单元划分、活动断层、活动褶皱、地壳升降运动、地震活动及新生代火山活动等方面论述了该地区的新构造及现代构造运动特征，最后讨论了该区和青藏高原形成的地球动力学问题。认为青藏高原在其形成过程中既有印度板块的向北俯冲和碰撞作用，又有塔里木块体的向南楔入，既有高原物质向外扩展作用，又有周边拗陷向高原内部渗透作用，所以青藏高原的岩石圈是处于一个四面受压，上出下入的动力学状态 相似文献
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As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains.Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghal-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation. 相似文献
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有关塔波尼亚的青藏高原运动学模型的要点及评述 总被引：3，自引：0，他引：3
经过１０多年对青藏高原的野外调查与研究,塔波尼亚提出了青藏高原运动学模型。该文就塔波尼亚的这一模型的主要观点和特色进行了简要的说明,并就若干问题作了评论与讨论。 相似文献
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Evolution characteristics of Quaternary tectonic stress field in the north and east margin of Qinghai-Xizang plateau 总被引：4，自引：1，他引：3
By inversion of fault slip data for Quaternary tectonic stress field and the analysis of crustal deformation after late Teriary, we explained the evolution of crustal dynamic about the north and east margin of Qinghai-Xizang (Tibet) plateau since Miocene. From middle or late Miocene to early Pleistocene, the tectonic stress field was featured by a maximum principal compression which was coming from the collision of India Plate perpendicular to the boundary of the plateau, and was basically of reverse faulting type. Since the late period of early Pleistocene, India Plate continued to push northward and the compressional deformation of the plateau interior increased continuously, meanwhile, NW-SE extension appeared on the east side of the plateau. This formed a favorable condition for the interior block of the plateau to slide towards east and southeast, causing the faults surrounding the plateau to change from thrust to strike-slip. The contemporary tectonic stress field was formed from the late period of early Pleistocene and continued to present. The direction of maximum principal compressional stress rotated clockwise with respect to the previous tectonic stress field, the stress field was mainly of strike-slip type. 相似文献
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新生代期间,中国大陆西部受印度一欧亚板块碰撞和青藏高原隆升影响,以地壳缩短、增厚、陆内造山和强烈地震活动等为主要特征.在青藏高原东北边缘,高原物质侧向移动被鄂尔多斯地块所阻,在六盘山地区发育了一系列左旋斜冲断裂.断裂带周缘构造变形强烈,地震活动频繁,是研究青藏高原横向扩展控制大陆内部弥散变形的理想场所.本文对穿越青藏高原东北缘一六盘山断裂带一鄂尔多斯地块的宽角反射与折射地震资料使用层析成像和射线反演算法进行成像,获得了研究区地壳速度结构模型,其结果反映出六盘山断裂带两侧地壳结构、构造特征差异显著:1)上地壳层析成像结果显示鄂尔多斯盆地一侧地壳上部速度较低,等值线呈近水平状,具有典型的沉积盆地特征,而青藏高原东北缘一侧上地壳速度相对较高,横向变化剧烈,呈褶皱状,二者的分界为海原一六盘山逆冲走滑断裂;2)全地壳射线反演结果显示鄂尔多斯地块地壳速度梯度大,下地壳底部速度高由铁镁质物质组成,具有典型稳定古老克拉通的特征,青藏高原东北缘地壳速度总体较低,主要由长英质及长英-铁镁质过渡物质组成,具有典型造山带的特征,而六盘山断裂带下方地壳速度结构复杂,层面呈拱形,部分层出现速度逆转,为两个构造单元的接触过渡带;3)青藏高原东北缘一侧地壳厚度~50 km,鄂尔多斯地块地壳厚度~42 km,六盘山断裂带下方莫霍面发生叠置,揭示出青藏高原东北缘、鄂尔多斯地壳在六盘山下汇聚,较薄且刚性的鄂尔多斯地壳挤入较厚且塑性的青藏高原东北缘地壳中的构造模式. 相似文献
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《Physics of the Earth and Planetary Interiors》1981,25(1):64-70
This paper presents a study of the tectonic stresses in central Asia based on an interpretation of satellite gravity data for mantle convection and supplemented with published fault plane solutions of earthquakes. Northwest-southeast to north-south compressional stresses exist in the Tien Shan region where reverse faulting dominates. The maximum compressive stress is oriented approximately northeast-southwest in the regions of Altai and southern Mongolia. Farther north, compressive stress gives way to tensional stress which causes normal faulting in the Baikal rift system. It is also shown that all of the tectonic stresses in the Tibetan plateau and Himalayan frontal thrust are related to the convection-generated stress patterns inferred from satellite gravity data. These results suggest that the complex crustal deformation in central Asia can be convincingly described by the deformation of the lithosphere on top of the up- and down-welling asthenospheric material beneath it. This observational fact may not only upset the simple view of the fluid crustal model of the Tibetan plateau, but also provide some useful constraints for the future development of deformation theory of continental crust. 相似文献
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本文采用分层黏弹性介质模型, 模拟了2015年4月25日尼泊尔MS8.1地震产生的同震和震后地表位移场, 计算了尼泊尔大地震引起的青藏高原及其周缘主要断裂上的同震和震后库仑应力变化。 地表位移场结果显示, 此次尼泊尔8.1级地震对中国大陆的影响区域主要是拉萨地块和羌塘地块, 对拉萨块体的影响主要表现为水平向南朝喜马拉雅构造带的汇聚作用, 垂直同震位移以下降为主, 震后以上升为主。 静态库仑破裂应力变化的计算结果显示, 尼泊尔大地震对青藏块体中南部的拉张性断层影响最为显著, 其中, 使尼泊尔地震北部的拉张断层的库仑应力显著增加, 个别断层库仑应力增加量超过0.01MPa, 而使其两侧的拉张断层库仑应力明显降低; 对青藏块体中部的走滑断裂则以正影响为主; 另外, 对南北地震带主要以负影响为主, 但量值微小。 相似文献
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青藏高原东北缘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,是研究青藏高原变形加厚的关键地区.本文利用"中国地震科学台阵探测"项目在南北地震带北段布设的密集宽频带流动台阵资料,采用虚拟地震测深方法（VDSS）,对青藏高原东北缘及周边地区的地壳厚度进行了研究,以期为研究青藏高原东北向扩展的前缘位置,以及扩展的动力学模式等提供地球物理学依据.波形模拟的结果显示,研究区地壳厚度变化剧烈.其中,祁连和西秦岭地块内地壳厚度存在明显的东西向横向变化,以103°E为界,东部地区为45~50 km,而西部地区地壳已明显增厚,约达到55 km以上.与祁连造山带相邻的阿拉善块体南缘地壳也明显加厚,接近55 km,而阿拉善块体内部地壳厚度约为45~50 km.与其他研究地区相比,鄂尔多斯地块地壳相对要薄,但整体而言,鄂尔多斯地块地壳呈现南北薄（约45 km）、中央厚（约50 km）的形态特征.此外,在六盘山断裂带台站下方观测到复杂的SsPmp震相,推测为双Moho界面结构.结合其他地球物理学证据,我们认为青藏高原东北缘地区地壳增厚方式以均匀缩短增厚为主,且高原向北东扩展的前缘已越过祁连山北缘断裂,进入阿拉善块体南缘地区. 相似文献
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青藏高原北部活动地块内部的活断层定量资料 总被引：5，自引：0，他引：5
文中定义了祁连山活动地块的边界,列表给出了近十几年来在青藏高原北部活动地块内部的活断层定量资料。其内容主要包括:活断层的编号、名称、产状、主要的地质地貌标志、活动年代、断层分段、断层滑动速率、古地震及其年代、地震破裂带的主要特征等。这些资料表明:青藏高原北部活动地块的8级大地震集中在它的边界活断层上,断层的滑动速率都在5~12mm/a左右;7级左右的地震发生在其内部规模较小的断层上,断层的滑动速率都在1~3mm/a左右;青藏高原北部活动地块内部的活断层,可以将该活动地块划分为几个次级地块,这些次级活动地块以变形为主,没有发生旋转;我们的结果支持青藏高原"连续变形"的假说 相似文献