Collaborative Research: Uplift or climate change? Determining the primary driver of deep canyon incision in the eastern cordillera, southern Peru

在许多山区，由于构造抬升而形成的新地貌与侵蚀新地貌的侵蚀之间存在竞争。地球科学家认识到，河流的侵蚀能力取决于向山脉输送了多少水，而更潮湿或更干燥的气候之间的变化应该会影响地形。人们的期望是，气候的变化和由此产生的侵蚀变化反映在地貌上。该项目的重点是秘鲁南部的东科迪勒拉，在那里雕刻在安第斯高原中部边缘的深峡谷反映了构造抬升或气候变化导致的侵蚀效率的增加。这项研究结合了新开发的诊断气候对地形影响的方法，作为基于现场的调查的一部分，以确定气候驱动的侵蚀效率变化对峡谷切割的影响程度。新的遥感分析方法被用来区分地形上构造抬升驱动的侵蚀和气候驱动的侵蚀的特征。提高这些远程方法的保真度具有相当大的社会价值，因为它们是在构造隆起的存在或不存在以及由此对地震活动的影响不确定的地区进行风险评估的一种廉价而有效的手段。此外，该项目将通过以下方面造福社会：1)对三名美国研究生(包括两名女性)和几名秘鲁本科生进行基本的STEM培训；2)与秘鲁和德国的大学进行国际合作；以及3)在本科生、研究生和专业水平上改善秘鲁和美国的STEM教育发展。确定山脉隆起的活跃构造驱动因素和相关构造的几何形状对于解决气候和构造耦合的强度至关重要。这个项目测试了关于峡谷切割进入东科迪勒拉的近端驱动因素的相互竞争的假设：由活跃的岩石隆起驱动的切割与先前由气候变化引发的隆起的高原边缘的切割。结合变形历史、景观形态、降水格局、侵蚀和折返的时空格局的观测和分析，明确和定量地评价了活动岩石隆起和气候变化在景观演化中的相对重要性。分析的重点是：1.从现代河沙中宇宙成因的10Be浓度估计千年尺度的侵蚀速率；2.评估降雨在地形与侵蚀速率关系中的作用；3.分析补充研究提供的低温测温仪(AHE、AFT、ZHE)的冷却年龄；4.完善地质填图和开发平衡剖面；5.整合模型中的所有数据以定量检验假设。研究结果将对以下方面产生广泛的影响：1.基于地貌数据分析提出的诊断峡谷切割主要原因的方法的普遍适用性和保真度，2.进一步开发一种方法，将几何形状、位移和断层上的速率与挖掘率、侵蚀率模式和由此产生的景观形态定量联系起来，3.基于观测的定量理解侵蚀率对年降雨量的敏感性，以及4.了解气候、地形、侵蚀和构造之间联系的性质和强度。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Competition between the growth of new topography by tectonic uplift and erosion that wears it down occurs in many mountain regions. Earth scientists recognize that the ability of rivers to erode depends on how much water is delivered to the mountains, and that changes between wetter or dryer climates should influence topography. The expectation is that changes in climate and the resulting change in erosion are reflected in the topography of a landscape. This project focuses on the Eastern Cordillera of southern Peru, where deep canyons carved into the Central Andean Plateau margin reflect either tectonic uplift or an increase in erosional efficiency due to climate change. The research incorporates newly-developed methods for diagnosing the effects of climate on topography as part of a field-based investigation to determine the degree to which climate-driven changes in erosional efficiency are responsible for canyon cutting. New remote analysis methods are used to differentiate signatures of tectonic uplift driven erosion and climate driven erosion in topography. Improving the fidelity of these remote methods has considerable societal value because they are an inexpensive and efficient means of hazard assessment in areas where the presence or absence of tectonic uplift, and the resulting effect on seismicity, are uncertain. Additionally, this project wll benefit society by: 1) essential STEM training of three US graduate students including two women, as well as several Peruvian undergraduates; 2) international collaborations with both Peruvian and German universities; and 3) improved STEM education development in Peru and US at the undergraduate, graduate, and professional levels.Determination of an active tectonic driver of mountain uplift and the geometry of related structures is critical to resolving how strongly climate and tectonics are coupled. This project tests competing hypotheses for the proximal drivers of canyon cutting into the Eastern Cordillera: incision driven by active rock uplift vs. incision into a previously uplifted plateau margin triggered by climate change. Integration of observations and analyses of the deformation history, landscape morphology, precipitation patterns, and spatial and temporal patterns of erosion and exhumation is used to definitively and quantitatively evaluate the relative importance of active rock uplift and climate change in landscape evolution. Analyses focus on: 1. estimating millennial-scale erosion rates from cosmogenic 10Be concentrations in modern river sands, 2. assessing the role of rainfall in the relation between topography and erosion rate, 3. analyzing cooling ages of low-temperature thermochronometers (AHe, AFT, ZHe) provided by a complementary study, 4. refining geologic mapping and developing balanced cross sections, and 5. integrating all data in models to quantitatively test hypotheses. Results will have broad implications for: 1. the general applicability and fidelity of proposed methods for diagnosing the primary causes of canyon cutting based on analysis of geomorphic data, 2. further development of a methodology to quantitatively link geometry, displacement and rates on faults to exhumation rates, erosion rate patterns and the resulting landscape morphology, 3. quantitative, observation-based understanding of the sensitivity of erosion rates to annual rainfall, and 4. understanding of the nature and strength of linkages among climate, topography, erosion, and tectonics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.