Collaborative Research: GPS Study of the Kinematics of the India-Eurasia Convergence Zone across the Pamir and Adjacent Terrain

合作研究：跨帕米尔及邻近地形的印度-欧亚大陆交汇带运动学的 GPS 研究

• 批准号: 0636092
• 负责人: Peter Molnar
• 金额: $ 5.87万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0636092&HistoricalAwards=false
• 关键词: Collaborative; Research; GPS; Study; Kinematics

The Pamir, Tajik Depression, and surrounding territory offer unusually good field laboratories for addressing three basic questions in large-scale continental geodynamics. First, the clearest example of intracontinental subduction lies at the boundary between the Pamir and the South Tien Shan in Tajikistan and Kyrgyzstan, where localized intracontinental convergence at 10-20 mm/yr may occur. Second, the Pamir provide a miniature version of the Tibetan Plateau; deformation seems to be slow and dominated by east-west extension through normal and strike-slip faulting despite being in the direct path that India approaches Eurasia. Third, many, apparently independent crustal blocks of the Tajik Depression seem to move as nearly rigid blocks over a layer of weak salt. Many think that deformation at all scales in continental regions is best described by such blocks. This region offers an especially good testing region of block movements with a simple rheological structure. GPS geodesy allows for very precise observations of strain and displacement at the surface of the earth. With an appropriate network of these observations, the hypothesis of intracontinental subduction in the South Tien Shan, including estimation of whether subduction is accommodated on a single dislocation, as in oceanic subduction zones, or over a distributed region can be tested. In the former case, inversions of GPS observations provide estimates of the subduction zone geometry, including strike, dip, and locking depth. The same style of observation will be used throughout the Pamir to quantify surface strain rates and their spatial arrangement to test whether deformation occurs slowly because the region is underlain by strong lithosphere or because the equilibrium between forces per unit length applied to its margins and stresses due to high, isostatically compensated topography balance to put the region under little stress. Finally, in the Tajik Depression, the GPS observations of velocity vectors for individual crustal blocks will be used to test theoretical formulations of finite strain in systems of many small interacting blocks. These types of models have been used to describe other regions of continental deformation, especially within the Tibetan Plateau, even when few blocks have direct velocity observations, but a thorough investigation of multiblock systems has not been previously made. To address these questions, and to increase GPS coverage of regional deformation in eastern Asia, the measurement of at least 50 new and existing campaign GPS sites, with at least 3 continuous GPS sites in Tajikistan and Kyrgzystan will be carried out over the next five years. Campaign measurements involve multiple short occupations of survey benchmarks with GPS instruments; continuous measurements involve fixed instruments recording data continuously. Scientists from the University of Montana, the University of Colorado, the Russian Academy of Sciences, Bishkek, and the Institute of Earthquake Engineering and Seismology of the Academia of Sciences of the Republic of Tajikistan will make and interpret these measurements.Many ideas about how continents deform tectonically have been developed using the Tibetan Plateau as a test. However, with only a single example, it is impossible to figure out which characteristics of the Plateau are general properties of continental deformation, and which are special features unique to Tibet. Fortunately, the Pamir and Tien Shan regions in Tajikistan and Kyrgystan also represent active continental collision, and maybe even true continental subduction. Measurements of surface deformation and development of physical models in those regions can help us to more clearly understand how the continents fit into the system of plate tectonics. Integrating continental lithosphere correctly into tectonics theory also has more general significance to human communities. Oceanic subduction zones host the biggest earthquakes on the planet (such as the Sumatra earthquake). Can continental subduction zones generate equally large events? Or do the continents respond to tectonic forces in different ways? The answers to these questions are important for estimating and responding to seismic hazards in Central Asia.

帕米尔（Pamir），塔吉克（Tajik）抑郁症和周围地区提供了异常良好的实验室实验室，以解决大型大陆地球动力学中的三个基本问题。 首先，最清晰的倾斜俯冲示例在于塔吉克斯坦和吉尔吉斯斯坦的帕米尔和南田山之间的边界，那里可能发生10-20 mm/yr的局部内部收敛。其次，帕米尔（Pamir）提供了藏族高原的微型版本；尽管印度接近欧亚大陆的直接道路，但变形似乎很慢，通过正常和滑移断层的东西向东西向延伸而占主导地位。第三，许多显然是塔吉克凹陷的独立地壳块似乎在移动，因为几乎刚性块在一层弱盐上。许多人认为，大陆区域中所有尺度的变形最好用这种区块描述。 该区域提供了一个特别好的测试区域，具有简单的流变结构。 GPS GEODESY允许非常精确地观察到地球表面的应变和位移。 通过适当的观察网络，南蒂恩（South Tien Shan）的载肠间俯冲的假设包括估计是否在单个位错上容纳俯冲，例如在海洋俯冲区中，或者可以测试分布式区域。 在前一种情况下，GPS观测的反转提供了俯冲带的几何形状的估计，包括打击，倾斜和锁定深度。 在整个PAMIR中，将使用相同的观察方式来量化表面应变速率及其空间排列，以测试变形是否缓慢发生，因为该区域被强岩石圈覆盖，或者是因为施加在其边缘的每单位长度和压力之间的平衡，并且由于其高度，高度，等于等立的，等立的补偿地形在压力下平衡。最后，在塔吉克抑郁症中，在许多小型相互作用块的系统中，将使用对单个地壳块的速度向量的GPS观测值来测试有限菌株的理论表述。 这些类型的模型已被用来描述大陆变形的其他区域，尤其是在藏族高原内，即使很少有块具有直接的速度观测，但以前尚未对多块系统进行彻底的研究。为了解决这些问题，并提高东亚地区变形的全科医生覆盖范围，将在未来五年内进行至少50个新的和现有的竞选GPS网站的测量，其中至少有3个连续的GPS网站。 广告系列测量涉及使用GPS工具对调查基准测试的多个短期职业；连续测量涉及连续记录数据的固定仪器。 蒙大拿大学，科罗拉多大学，俄罗斯科学院，比什基克大学，比什凯克大学以及地震工程学院和塔吉基斯坦科学学术界的地震学研究所的科学家将进行和解释这些测量。对剧烈构件的持续性构成的想法是如何使用藏tibetan palleau sesteau sesteau sesteau sesten。 但是，只有一个例子，就无法确定高原的哪些特征是大陆变形的一般特性，哪些是西藏独有的特殊特征。 幸运的是，塔吉克斯坦和吉尔吉斯坦的Pamir和Tien Shan地区也代表了积极的大陆碰撞，甚至可能是真正的大陆俯冲。 这些区域中表面变形和物理模型的发展的测量可以帮助我们更清楚地了解大陆如何适应板块构造系统。 将大陆岩石圈正确整合到构造理论中也对人类社区具有更大的意义。 海洋俯冲带在地球上拥有最大的地震（例如苏门答腊地震）。 大陆俯冲带可以产生同样大的事件吗？ 还是大陆以不同的方式对构造力量做出反应？这些问题的答案对于估计和应对中亚的地震危害很重要。