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

合作研究：量化古地形和古气候以测试秘鲁安第斯山脉的地球动力学模型

• 批准号: 1550101
• 负责人: Christopher Poulsen
• 金额: $ 20.82万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1550101&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; Paleotopography; Paleoclimate

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.

尽管板块构造为山带的起源提供了一级解释，但驱动山带表面隆起和折返的构造过程并未得到很好的理解。更不清楚的是隆升、侵蚀过程和气候之间的相互作用，这些因素塑造了山脉的景观。这个项目使用最先进的技术来研究秘鲁安第斯山脉的构造、侵蚀和气候的相互作用，以测试关于安第斯山脉隆起的新的和有争议的想法。该项目通过以下途径促进取得预期的社会成果：(1)妇女和任职人数不足的少数群体充分参与STEM，途径是支持女性研究人员和学生，以及针对任职人数不足的少数群体的高中生和本科生的外联方案；(2)通过参加为任职人数不足的少数群体的高中生和本科生提供研究经验的外联方案，提高公众的科学素养和公众参与度；(3)通过本科生和研究生培训和支持几名早期职业研究人员，发展一支多样化、具有全球竞争力的STEM工作队伍；以及(4)通过国际合作增加伙伴关系。地球科学构造学和地貌与土地利用动力学项目部和美国国家科学基金会国际科学与工程办公室支持这一项目。地球表面地形直接响应地幔过程和板块构造，控制地表排水和泥沙运移模式，并影响大气环流和气候。作为大洋-大陆俯冲高地的典型例子，中央安第斯山脉对于评价造山作用的地球动力学模型至关重要。尽管以前对构造历史、过去的高程和切割记录的研究提供了关于地表隆升的重要见解，但这些研究也表明了一系列不同的隆升历史和相关的构造驱动因素。目前安第斯造山作用的地球动力学模型包括：(1)晚新生代地壳持续增厚和缩短，导致地表逐渐抬升和峡谷切割；(2)晚新生代南美岩石圈拆沉，导致地表快速抬升和晚中新世脉动切割；(3)早新生代收缩驱动的地壳增厚，导致晚始新世西侧近现代的抬升，并通过新生代向东传播形变。为了区分不同的模式，本项目使用：(1)火山玻璃和土壤碳酸盐的稳定同位素分析，以提供对古海拔随时间变化的定量估计，并结合地质年代学以限制时间；(2)有助于同位素的大气环流模拟，以确定海拔变化对气候的影响，并定量解释稳定同位素数据，受现代海拔-同位素和气候-同位素关系的制约；(3)经数据验证的河流侵蚀模拟，以预测对不同模型的侵蚀反应；(4)河流和湖泊沉积学和沉积物来源，以确定流域系统范围和盆地发展的变化。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，并区分拟议的构造和气候控制。