Collaborative Research: Discrete vs. Continuous Continental Deformation and the Role of the Lower Crust in the Tien Shan

0310039帕克该奖项为主动地震反射计划提供支持，并在天山造山带西部、吉尔吉斯斯坦和中国西北部进行被动地震和MT测量。天山是与印度-欧亚大陆碰撞有关的陆内厚皮挤压变形的一个引人注目的例子，占这次碰撞变形的一半左右，而且它是活跃的。 现有的结果表明，在天山的北方和南部边缘附近的变形集中，不均匀的电阻率结构，包括高电阻率区延伸到莫霍面深度，和GPS变形测量与地质测量估计周围的主要变形断层和累积的造山带。新的工作是建立允许两种不同的手段之间的选择，以适应下地壳的挤压变形;一个离散断层的最高地幔深度，和其他连续的韧性增厚下地壳。 这项工作的基石是一个密集的CMP反射剖面，以寻找可追溯到上地幔的地壳尺度断层带，作为第一个模型的验证。 额外的被动地震工作主张测试较高的T地幔向上渗透到莫霍面大概作为一种手段，刺激下地壳的韧性和寻找上地幔界面。 MT工作的目的是重新处理和反演较旧的苏联时代MT数据，据称质量相当好，以提供与拟议地震线重合的覆盖范围，并收集更多的地点进入塔里木盆地，以改善采样和解决可能与塔里木天山过渡相关的结构。***

0310039ParkThis award provides support for an active seismic reflection program, and follow up passive seismic and MT surveying in the western Tien Shan orogen, Kyrgystan and NW China. The Tien Shan is a spectacular example of intracontinental thick-skinned compressional deformation associated with the India-Eurasia collision, taking up about half of this collision's deformation, and it is active. Existing results show a concentration of deformation near the northern and southern margins of the Tien Shan, inhomogeneous resistivity structure including high resistivity zones extending to Moho depths, and GPS deformation measurements which correlate with geological measurements estimated around the major deforming faults and cumulative over the orogen. The new work is set up to allow a choice between two distinct means of accommodating the compressional deformation in the lower crust; one by discrete faulting to uppermost mantle depths, and the other by continuous ductile thickening in the lower crust. A cornerstone of the effort is a dense CMP reflection profile to search for crustal scale fault zones traceable to the upper mantle as a verification of the first model. Additional passive seismic work is advocated to test for higher-T mantle upwellings penetrating toward the Moho presumably as a means of stimulating lower crustal ductility and to search for upper mantle interfaces. MT work is aimed at reprocessing and inverting older Soviet-era MT data stated to be of fair-good quality to provide coincident coverage with the proposed seismic line, and to collect additional sites into the Tarim Basin to improve sampling and resolve possible structures associated with the Tarim-Tien Shan transition. ***