Uplift History of the Cordillera Occidental, Southern Peru, from Canyon Geomorphology

从峡谷地貌看秘鲁南部西科迪勒拉山脉的隆起历史

• 批准号: 0836203
• 负责人: Kip Hodges
• 金额: $ 2.17万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0836203&HistoricalAwards=false
• 关键词: Uplift; History; Cordillera; Occidental; Southern

Massachusetts Institute of Technology (MIT) researchers are studying the uplift history of the Cordillera Occidental of southern Peru, which marks the western boundary of the Altiplano plateau in the central Andes. Their approach is to study the spatial and temporal history of incision of two major river systems (the Colca and Cotahuasi river systems) that transect the range through what are regarded as the two deepest canyons in the Western Hemisphere, each with a total relief in excess of 3200 meters. Although river incision is an imperfect proxy for rock uplift, the behavior of major river systems during tectonic activity is a sensitive indicator of surface uplift relative to sea level. This is true regardless of whether or not steady-state conditions have been met. The geology and geography of these drainages provide four independent ways to estimate the history and pattern of river incision. This circumstance provides an extraordinary opportunity to develop a detailed image of the incision history of the Colca and Cotahuasi river systems, which the MIT researchers are using to deduce the uplift evolution of the western edge of the Altiplano, and to test the implicit assumptions in standard applications of each of the four methods. The MIT researchers are using a combination of the following four methods to decipher the history and pattern of river incision: 1) thermochronologic studies of incised granitic plutons; 2) reconstructions of ancient land surfaces based on preserved remnants of volcanic flows; 3) measurements of the time-integrated rate of river incision using bedrock strath terraces; and 4) reconstructions of the history of valley aggradation and subsequent re-excavation recorded in alluvial fill terraces and remnants of volcanic infills. The information being gleaned from these studies about the incision histories of the Colca and Cotahuasi river systems is essential for evaluating current models of the growth and uplift of the Andes, and for better informing future models.

马萨诸塞州理工学院（MIT）的研究人员正在研究秘鲁南部山脉西部的隆起历史，该历史标志着中部安第斯山脉的阿尔特普拉诺高原的西部边界。他们的方法是研究两个主要河流系统（Colca和Cotahuasi River Systems）切口的空间和时间历史，这些系统通过被认为是西半球的两个最深峡谷的范围，每个范围都有过多的宽慰3200米。尽管河流切口是岩石上升的不完善的代理，但构造活动期间主要河流系统的行为是相对于海平面的表面升高的敏感指标。无论是否满足稳态条件，这都是事实。这些排水的地质和地理提供了四种独立的方法来估计切口的历史和模式。这种情况提供了一个非凡的机会，以开发Colca和Cotahuasi River Systems的切口历史的详细图像，麻省理工学院研究人员用来推断Altiplano西部边缘的提升演变，并测试标准中隐含的假设四种方法中每种应用的应用。 麻省理工学院的研究人员正在使用以下四种方法的组合来破译河流切口的病史和模式：1）切开的花岗岩岩体的热量研究； 2）基于保存的火山流遗迹重建古老的陆地表面； 3）使用基岩Strath露台测量河流切口的时间集成率；和4）在冲积填充露台和火山填充物的残余物中记录的山谷促进史以及随后的再挖掘的历史的重建。这些有关Colca和Cotahuasi River Systems的切口历史的研究从这些研究中收集的信息对于评估安第斯山脉的增长和提升的当前模型以及更好地告知未来模型至关重要。