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

俄亥俄州立大学和夏威夷大学的一个科学家小组正在玻利维亚境内安第斯高原的整个东侧和阿根廷最北部建造一个密集的全球定位系统网络，以解决有关造山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当代的形变模式，重点放在其东侧，即由东科迪莱拉、安第斯间带和亚安第斯山脉组成的东侧。为了更好地了解造山楔体过程，他们的研究小组将：(1)确定强烈的东侧速度梯度是基底滑脱上的滑动锁定过渡带的信号，还是无序逆冲作用的信号；(2)测量Santa Cruz弯曲南北活动楔体的宽度差异，并确定其与弯曲两侧降雨差异(作为侵蚀的指标)的关系；(3)评估活动缩短从高原较深的内侧部分转移到较浅的外侧楔体的机制。安第斯高原运动学将通过以下方面来阐明：(1)确定安第斯高原东侧的运动格架；(2)测量活动缩短沿走向的变化；(3)古地理和前陆盆地地层学对地壳位移和前陆缩短的影响；(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；(5)在北亚大陆主要地貌过渡带或地貌斜坡上寻找挤压构造的证据。造山高原在地质历史的大部分时间里都有形成，由于它们是由大规模地壳增厚和大规模地壳熔融形成的，它们的形成对大陆地壳的演化起着重要的作用。了解高原造山机制的最好前景是研究活跃的大陆高原，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，并有助于加深对高原东部边缘活动过程的理解。这个项目应该有助于更深入地了解山地地带和地形高原的变形方式。这项研究应该会提高人们对高山两侧人口稠密地区地震产生的理解。

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.