Collaborative Research: Geodetic Constraints on the Tectonic Processes Operating at the East Flank of the Central Andean Plateau

来自俄亥俄州立大学和夏威夷大学的一组科学家正在玻利维亚境内的安第斯高原整个东侧和阿根廷最北端建立一个密集的GPS网络，以解决有关造山带楔形过程和安第斯高原边缘运动学的各种问题。该项目将研究安第斯高原的当代变形模式，并将重点放在它的东侧翼，包括东科迪勒拉、跨安第斯带和亚安第斯山脉。为了更好地理解造山带的楔形过程，他们的研究团队将：(1)确定一个强烈的东侧翼速度梯度是基底滑脱上的滑锁过渡带还是序外逆冲的信号；(2)测量圣克鲁斯弯曲南北活动楔的宽度差异，并确定其与弯曲两侧降雨量差异（作为侵蚀的代表）的关系；(3)评估主动缩短从高原较深的舷内部分转移到较浅的舷外楔的机制。安第斯高原运动学将通过：(1)确定安第斯高原东翼的运动学框架；(2)主动缩短沿走向变化的测量；(3)古地理和前陆盆地地层对地壳位移和前陆缩短的影响评价；(4)查帕雷地区前陆盆地古生代沉积缺失与科恰班巴剪切带的关系研究；(5)在北亚安第斯山脉上方的主要地形过渡或地形斜坡中寻找挤压构造的证据。造山高原的形成贯穿了整个地质历史，由于是地壳大规模增厚和大规模熔融的产物，造山高原的形成在大陆地壳演化中起着重要作用。了解高原造山作用机制的最佳前景是研究活跃的大陆高原，例如安第斯山脉中部的高原。目前关于这一高原发育的理论表明，要么是缓慢的两阶段隆升过程，要么是快速隆升的情景。这项研究将提供有助于解决这一争议的数据，并提高对高原东部边缘活动过程的理解。这个项目应该会让我们对山带和地形高原的变形方式有更深入的了解。这项研究将提高人们对高山两侧人口密集地区地震成因的认识。

A team of scientists from Ohio State University and the University of Hawaii is constructing a dense GPS network over the entire eastern flank of the Andean Plateau within Bolivia and northernmost Argentina in order to address a variety of questions about orogenic wedge processes and Andean plateaus margin kinematics. The project will to study contemporary patterns of deformation in the Andean Plateau, and focus on its eastern flank, which is comprise of the Eastern Cordillera, the Interandean Zone, and the Subandes. To better understand orogenic wedge processes they research team will: (1) determine whether a strong eastern flank velocity gradient is a signal of a slipping-locked transition zone on the basal decollement or of out-of-sequence thrusting; (2) measure differences in the width of the active wedge north and south of the Santa Cruz bend and determine its relationship to the differences in rainfall (as a proxy for erosion) on either side of the bend; (3) assess mechanisms by which active shortening is transferred from the deeper, inboard portions of a plateau to the shallower outboard wedges. Andean plateau kinematics will be elucidated by: (1) determination of the kinematic framework of the east flank of the Andean plateau; (2) measurement of the variation of active shortening along-strike; (3) assessment of the influence of paleogeography and foreland basin stratigraphy on crustal displacement and foreland shortening; (4) examination of the relationship between the absence of Paleozoic sediments in the foreland basin of the Chapare region and the Cochabamba Shear Zone; (5) exploration for evidence of extrusion tectonics in the main physiographic transition or topographic ramp above the northern Subandes.Orogenic plateaus have formed throughout much of geological history, and because they are produced by massive crustal thickening accompanied by large scale crustal melting, their formation plays an important role in the evolution of continental crust. The best prospect for understanding the mechanisms responsible for plateau orogenesis is the study of active continental plateaus, such as the plateau in the central Andes. Current theories for the development of this high plateau suggest either a slow two-stage uplift process or a rapid uplift scenario. This study will provide data that will contribute to the resolution of this controversy as well as improve understanding of the active processes along the plateau's eastern margin. This project should lead to a deeper understanding of the way that mountain belts and topographic plateaus deform. The research should improve understanding of the generation of earthquakes in the highly populated regions flanking high mountains.