GPS Study of the Kinematics of the Intersection of the Tarim, Tien Shan, and Pamir

高质量的结果，从一个密集的GPS网络，从天山中部，从哈萨克斯坦，通过吉尔吉斯斯坦，并进入中国，揭示了一个相对简单的运动学图片的东部塔拉斯费尔干纳断层。 几项独立研究的GPS速度一致认为，塔里木盆地和哈萨克地台之间的会聚速度约为20 mm/年，约为印度板块和欧亚板块之间总会聚速度的一半。 来自PI密集网络的GPS速度表明，收敛仅局限于少数结构。 从地质研究和大地测量研究中推断出的这些结构的滑动速率非常吻合。 PI使用了这个新的大地测量数据，结合一个简单的块体模型，解释弹性应变积累，以反演该地区地壳块体的运动。 值得注意的结果包括塔拉斯-费尔干纳断层的右旋运动比以前的地质估计要少得多，费尔干纳山谷的旋转速度约为0.8度/百万年（古地磁长期地质速率的一小部分），帕米尔和南天山之间的阿拉伊山谷的收敛速度约为20毫米/年，与以前的估计相当。然而，西部现有的大地测量覆盖范围，跨越塔拉斯-费尔干纳断层进入费尔干纳盆地，以及南部跨越阿拉伊河谷和南天山进入帕米尔，比中天山更稀疏，精度更低。 塔拉斯费尔干纳断层上的走滑运动、费尔干纳盆地的旋转和阿拉伊河谷的汇聚速率没有得到很好的约束。 例如，推断的费尔干纳盆地的旋转速率相差两倍，这取决于GPS结果用于约束模型。 显然，需要进行更多的观测，才能在这一地区获得与东部地区类似的有用结果。 此外，拟议对PI的原始GPS数据与其他机构（GFZ和CSB）采集的数据进行联合分析，将提供一种精度更高的综合解决方案。在与吉尔吉斯斯坦的俄罗斯高温物理研究所（IVTRAN）的同事合作下，PI建议在吉尔吉斯斯坦西部和乌兹别克斯坦安装20个新站点。 位于中国武汉的中国地震局（CSB）将与我们合作，在中国西北部的新疆省安装更多的站点（确切数量和位置将在实地考察后确定）。PI的合作者将调查这些站点，以及GFZ，IVTRAN和CSB先前在该地区安装的现有站点，以揭示天山，费尔干纳盆地，帕米尔和塔里木盆地相交地区的运动学。 除了分析GPS数据外，他们还将使用简单的基于连续介质力学的模型来解释他们根据地质运动获得的GPS速度。

High quality results from a dense GPS network spanning the Central Tien Shan, fromKazakhstan, through Kyrgyzstan, and into China, reveal a relatively simple kinematic picture to the east of the Talas-Ferghana fault. GPS velocities from several independent studies agree that there is ~20 mm/yr convergence between the Tarim Basin and the Kazakh platform, about half the total convergence between the Indian and Eurasian plates. GPS velocities from the PI's dense network show that convergence is localized on a handful of structures. Slip rates on these structures inferred from both geologic studies and geodetic studies agree remarkably well. The PI's have used this new geodetic data, in conjunction with a simple block model that accounts for elastic strain accumulation, to invert for the motions of crustal blocks in the region. Notable results include much less right-lateral motion on the Talas-Ferghana fault than the previous geological estimate, rotation of the Ferghana Valley at ~0.8 degree/myr (a fraction of the long-term geologic rate from paleomag), and convergence across the Alay valley between the Pamir and Southern Tien Shan of ~20 mm/yr, comparable to previous estimates. However, existing geodetic coverage in the west, across the Talas-Ferghana fault into the Ferghana basin, and south across the Alay valley and South Tien Shan and into the Pamir, is both more sparse and less accurate than that in the Central Tien Shan. These rates of strike-slip motion on the Talas Ferghana fault, rotation of the Ferghana basin,and convergence across the Alay valley are not well constrained. For example, the inferred rate of rotation of the Ferghana basin differs by a factor of two depending upon which GPS results are used to constrain the model. Clearly, more observations are needed to obtain results in this area comparable in usefulness to those obtained to the east. In addition, the proposed joint analysis of the PI's raw GPS data with that taken by others (GFZ and CSB) will provide a combined solution with improved accuracy. In collaboration with colleagues at the Russian Institute for High Temperature Physics (known as IVTRAN)in Kyrgyzstan, the PI's propose to install 20 new sites in western Kyrgyzstan and Uzbekistan. The Chinese Seismological Bureau (CSB)in Wuhan, China, will work with us to install additional sites in northwestern Xinjiang Province in China (exact number and locations to be determined after a visit to the field). The PI's collaborators will survey these sites, as well as existing sites that GFZ, IVTRAN, and CSB previously installed in the region, in order to unravel the kinematics of the area where the Tien Shan, Ferghana Basin, Pamir, and Tarim Basin intersect. In addition to analyzing the GPS data, they will also use simple continuum mechanics-based models to interpret the GPS velocities that they obtain in terms of geologic motions.