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

来自俄亥俄州州立大学和夏威夷大学的一个科学家小组正在玻利维亚和阿根廷最北部的安第斯高原整个东侧建造一个密集的全球定位系统网络，以解决有关造山楔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，重点是其东侧，包括东科迪勒拉，安第斯山脉带和Subandes。为了更好地理解造山楔过程，他们的研究小组将：（1）确定强烈的东翼速度梯度是基底滑脱上的滑动锁定过渡带还是序列外逆冲的信号;（2）测量活动楔形体在圣克鲁斯弯曲北部和南部的宽度差异，并确定其与降雨差异的关系（作为侵蚀的代表）在弯曲的任一侧;（3）评估主动缩短从高原的较深内侧部分转移到较浅外侧楔形的机制。安第斯高原的运动学将通过以下几个方面来阐明：（1）确定安第斯高原东翼的运动学格架;（2）测量沿走向主动缩短的变化;（3）评估古地理和前陆盆地地层对地壳位移和前陆缩短的影响;（4）查帕雷地区前陆盆地缺乏古生代沉积与科恰班巴剪切带的关系;（5）在北方亚带上方的主要自然地理过渡或地形斜坡中探索挤压构造的证据。造山高原在地质历史的大部分时间里都是形成的，由于它们是伴随着大规模地壳熔融而发生的大规模地壳增厚，因此它们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对活动大陆高原的研究，如安第斯山脉中部的高原。目前关于这一高原发展的理论认为，要么是一个缓慢的两阶段隆升过程，要么是一个快速隆升过程。这项研究将提供有助于解决这一争议的数据，以及提高对高原东缘沿着活动过程的理解。该项目将导致对山区带和地形高原变形方式的更深入理解。这项研究将提高对高山两侧人口稠密地区地震发生的理解。

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.