Collaborative Research: Quantifying Paleotopography and Paleoclimate to Test Geodynamic Models in the Peruvian Andes

虽然板块构造理论对山带的起源提供了一级解释，但对推动地表隆起和山带挖掘的构造过程却知之甚少。更不为人所知的是隆起、侵蚀过程和气候之间的相互作用，这些相互作用塑造了山地景观。该项目使用最先进的技术来研究秘鲁安第斯山脉的构造、侵蚀和气候之间的相互作用，以测试有关安第斯山脉隆起的新的和有争议的想法。该项目通过以下方式促进预期的社会成果：(1)通过支持女性研究人员和学生以及面向来自代表性不足的少数族裔的高中和本科学生的外展项目，使女性和代表性不足的少数族裔充分参与STEM；(2)通过为来自未被充分代表的少数民族的高中生和本科生提供研究经验的外展项目，提高公众的科学素养和公众对STEM的参与；(3)通过对本科生和研究生的培训以及对几位早期职业研究人员的支持，发展一支多元化的、具有全球竞争力的STEM劳动力队伍；(4)通过国际合作加强伙伴关系。地球科学、构造与地貌学和土地利用动力学项目分部以及美国国家科学基金会国际科学与工程办公室支持了这个项目。地球表面地形直接响应地幔过程和板块构造，控制地表排水和沉积物运输模式，并影响大气环流和气候。作为洋陆俯冲形成的高地形的典型代表，中安第斯山脉是评价造山动力学模式的关键。虽然先前的构造史、过去海拔和切口记录的研究为地表隆起提供了重要的见解，但这些研究也表明了不同范围的隆起历史和相关的构造驱动因素。目前安第斯造山运动的地球动力学模式包括：(1)晚新生代地壳持续增厚和缩短，导致地表逐渐隆起和峡谷切割；(2)晚新生代南美岩石圈的拆沉作用，导致地表快速隆升和晚中新世的切口脉冲；(3)早新生代收缩驱动的地壳增厚，在始新世晚期导致西部接近现代的抬升，并在整个新生代将变形向东传播。为了区分不同的模型，本项目使用：(1)火山玻璃和土壤碳酸盐的稳定同位素分析提供了古海拔随时间的定量估计，并结合地质年代学来限制时间；(2)在现代海拔-同位素关系和气候-同位素关系的约束下，利用同位素模拟确定海拔变化对气候的影响，并定量解释稳定同位素数据；(3)基于数据验证的河流侵蚀模型，预测不同模型下的侵蚀响应；(4)河流与湖泊沉积学和沉积物物源，以识别流域系统范围和盆地发育的变化。通过综合这些数据，研究小组将量化造山演化过程中的地表地形和侵蚀，并区分提出的构造和气候控制。

Although plate tectonics provides a first-order explanation of the origin of mountain belts, the tectonic processes that drive surface the uplift and exhumation of mountain belts are not well understood. Even less well understood are the interactions of between uplift, erosional processes, and climate that shape the mountain landscape. This project uses state-of-the art to examine the interaction of tectonics, erosion, and climate in the Peruvian Andes to test new and controversial ideas concerning the uplift of the Andes. The project advances desired societal outcomes through: (1) full participation of women and underrepresented minorities in STEM through support of an female researchers and students plus outreach programs to high school and undergraduate students from underrepresented minorities; (2) increased public scientific literacy and public engagement with STEM through participation of outreach programs that provide research experiences for high school and undergraduate students from underrepresented minorities ; (3) development of a diverse, globally competitive STEM workforce through undergraduate and graduate student training and support of several early career researchers; and (4) increased partnerships through international collaboration. The Division of Earth Sciences Tectonics and Geomorphology & Land Use Dynamics Programs and the NSF Office of International Science and Engineering supported this project.Earth's surface topography responds directly to mantle processes and plate tectonics, controls surface drainage and sediment transport patterns, and influences atmospheric circulation and climate. As the type example of ocean-continent subduction-generated high topography, the Central Andes are critical to evaluating geodynamic models of orogenesis. Although previous studies of the structural history, past elevations, and incision record have provided important insights on surface uplift, these studies also suggest a disparate range of uplift histories and associated tectonic drivers. Current geodynamic models for Andean orogenesis include: (1) continuous late Cenozoic crustal thickening and shortening, resulting in gradual surface uplift and canyon incision; (2) late Cenozoic delamination of South American lithosphere, resulting in rapid surface uplift and a late Miocene pulse of incision; and (3) early Cenozoic contraction-driven crustal thickening, resulting in near modern elevations in the west by late Eocene and propagating deformation eastward through the Cenozoic. To distinguish between models, this project uses: (1) stable isotope analyses of volcanic glasses and soil carbonates to provide quantitative estimates of paleoelevations over time, coupled with geochronology to constrain timing; (2) isotope-enabled general circulation modeling to determine how changing elevations affected climate and to quantitatively interpret stable isotope data, constrained by modern elevation-isotope and climate-isotope relationships; (3) data-validated fluvial erosion modeling to predict the erosional response to different models; and (4) fluvial and lacustrine sedimentology and sediment provenance to identify changes in drainage system extent and basin development. By synthesizing these data, the research team will quantify surface topography and erosion during orogenic evolution and distinguish between proposed tectonic and climatic controls.