Tectonic and Climatic Controls on Rapid Exhumation Along the Altiplano-Eastern Cordillera Boundary, Bolivia

玻利维亚高原-东科迪勒拉边界沿线快速折返的构造和气候控制

• 批准号: 0510441
• 负责人: Brian Horton
• 金额: $ 17.27万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0510441&HistoricalAwards=false
• 关键词: Tectonic; Climatic; Controls; Rapid; Exhumation

Researchers from the University of California Los Angeles (UCLA) are investigating the role of tectonics and climate in driving rapid erosional exhumation in the central Andes Mountains of South America. In northern Bolivia, the central Andes are host to some of the highest topography, most rapid rates of exhumation, and greatest concentration of isotopic age data (thermochronological results) in the entire Andean mountain belt. The region also displays one of the most dramatic climatic gradients on Earth, from the extremely humid conditions of the Amazon watershed in the north to the arid conditions of the Parana watershed in the south. The focus of this multidisciplinary study is the evolution of a 4.5-6-kilometer-high narrow mountain range that defines the main physiographic divide between the Altiplano plateau and Amazon drainage system. Cenozoic uplift of this 30 by 250 kilometer range in the Eastern Cordillera had far-reaching effects, arguably (1) triggering growth of the 4-kilometer-high central Andean plateau, (2) inducing closed drainage in the Altiplano, (3) modifying regional climate by orographic effects, and (4) setting up a dynamic interplay between erosion and tectonics in a possible steady-state orogen. Previous isotopic ages from thermochronological studies generate conflicting interpretations which alternately invoke heating or cooling during either brief pulses (less than several million years) or prolonged episodes (several tens of millions of years) of deformation, erosion, and magmatism. The UCLA researchers are analyzing geologic structures, sedimentation, and thermal histories along two short (~30-kilometer-long) transects in northern Bolivia in order to understand erosional exhumation of the narrow mountain range in relationship to deformation and sedimentary basin development. Ongoing thermochronological analyses of the range and sedimentological studies of an adjacent basin are determining the function of individual structures in the range's cooling history as well as the timing of deformation and basin genesis. The project includes collaboration with Bolivian scientists and involves undergraduate and graduate students from the United States and Bolivia in field and laboratory research.Support for the project is provide by the Tectonics Program and by the Americas Group of the Office of International Science and Engineering.

来自加州大学洛杉矶分校（UCLA）的研究人员正在调查构造和气候在推动南美洲中部安第斯山脉快速侵蚀剥露中的作用。 在北方玻利维亚，中部安第斯山脉是整个安第斯山脉带中地形最高、挖掘速度最快、同位素年龄数据（热年代学结果）最集中的地区。 该地区还显示了地球上最引人注目的气候梯度之一，从北部亚马逊流域的极端潮湿条件到南部巴拉那流域的干旱条件。 这项多学科研究的重点是一个4.5-6英尺高的狭窄山脉的演变，它定义了Altiplano高原和亚马逊流域系统之间的主要自然地理分界线。 东科迪勒拉山脉30 × 250公里范围内的新生代隆起产生了深远的影响，可以说（1）触发了4米高的安第斯高原中部的增长，（2）在高原地区引发了封闭的排水系统，（3）通过地形效应改变了区域气候，（4）在可能的稳态造山带中建立了侵蚀和构造之间的动态相互作用。 以前的同位素年龄从热年代学研究产生相互矛盾的解释，交替调用加热或冷却期间要么短暂的脉冲（不到几百万年）或长期发作（数千万年）的变形，侵蚀，岩浆活动。 加州大学洛杉矶分校的研究人员正在分析玻利维亚北方两个短（约30英里长）断面沿着地质结构，沉积和热历史，以了解狭窄山脉的侵蚀剥露与变形和沉积盆地发育的关系。 正在进行的对山脉的热年代学分析和对邻近盆地的沉积学研究正在确定山脉冷却历史中各个结构的功能以及变形和盆地成因的时间。 该项目包括与玻利维亚科学家的合作，美国和玻利维亚的本科生和研究生参加了实地和实验室研究，该项目得到了构造学方案和国际科学与工程处美洲小组的支持。