Collaborative Proposal: Do arc-continent collisions in the tropics set the Earth's climate state?

合作提案：热带地区的弧大陆碰撞是否决定了地球的气候状态？

• 批准号: 1925489
• 负责人: Rebecca Flowers
• 金额: $ 27.92万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1925489&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Do; arc; continent

Over its history, Earth has experienced warm ice-free and cold glacial climates, but it is unknown if transitions between these background climate states were the result of changes in CO2 sources or sinks. On these multi-million year geological timescales, CO2 enters the ocean and atmosphere primarily by volcanic outgassing and is removed primarily though the chemical erosion of rocks, which delivers calcium and magnesium via rivers to the ocean where they react with CO2 to form carbonate. It is hypothesized that the tectonic closure of ocean basins and formation of mountains at equatorial latitudes could drive cooling by creating topography and eroding highly soluble oceanic rocks in the warm, wet tropics. This process increases global weatherability, thereby increasing Earth's potential to sequester CO2 in carbonates through chemical erosion. The investigators aim to test the hypothesis that changes in global weatherability have controlled the Earth's background climate state with coupled geological, geochemical, and modelling studies. This broader impact of this work will benefit society by generating and disseminating knowledge about geological climate change at both the K-12 and college level. The researchers have developed a global database of arc-continent collisions through the Phanerozoic, which mark the closure of former ocean basins, and reconstructed their position with state-of-the-art paleogeographic models. The results from this analysis revealed a temporal coincidence between the maximum global extent of arc-continent collision in the tropics and the occurrence of every major glacial period in the Phanerozoic. The investigators will refine geological constraints and tectonic reconstructions in five critical belts. Through these case studies, the researchers will generate thermochronological data and refine the exhumation history of New Guinea and construct a new paleogeographic model for suturing in the Alpine-Himalaya belt. The investigators will also acquire new stratigraphic, geochronological, geological, petrographic, geochemical, and paleomagnetic data along Permo-Carboniferous sutures from Mexico to South America, Ordovician sutures in the northern Appalachian, and Neoproterozoic sutures in the Arabian-Nubian Shield. These field and laboratory data will be integrated with paleogeographic, weathering, and climate models to develop estimates for the change in pCO2 resulting from arc-continent collisions in the tropics utilizing the GEOCLIM model framework. This framework integrates climate models run at varying pCO2 with global weathering models such that the variable climatology can be used to estimate the effect of changes in global weatherability model on long-term steady-state pCO2 levels. In this framework, the investigators will perform sensitivity tests to isolate the effects of specific parameters such as lithology or topography. The researchers will further calibrate these models with source-to-sink cation studies in modern and paleo ophiolite watersheds. Finally, they will develop statistical methods to evaluate the strength of correlation and test hypothesized causal mechanisms for environmental change. Through this research the investigators will directly train a postdoctoral researcher, 5 PhD students and numerous undergraduate research assistants. To disseminate this basic research, the team will hold public seminars and workshops with K-12 teachers, and construct classes on Tectonics and Climate with online course materials, both at the high-school and undergraduate level.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.

在其历史上，地球经历了温暖的无冰和冷冰川气候，但是尚不清楚这些背景气候状态之间的过渡是否是二氧化碳源或下沉量的变化的结果。在这些数百万年的地质时间尺度上，二氧化碳主要通过火山口燃料进入海洋和大气，主要是通过岩石的化学侵蚀来清除，该岩石的化学侵蚀通过岩石和镁通过河流传递到海洋中，它们与二氧化碳的反应与二氧化碳反应形成碳酸盐。假设海洋盆地的构造封闭和赤道纬度的山形成可以通过在温暖，湿的热带地区侵蚀高度可溶的海洋岩石来驱动冷却。该过程提高了全球的天气性，从而增加了地球通过化学侵蚀隔离碳酸盐的二氧化碳的潜力。研究人员旨在检验全球气候变化的假设，通过耦合地质，地球化学和建模研究控制了地球背景气候状态。这项工作的这一更广泛的影响将通过在K-12和大学一级产生和传播有关地质气候变化的知识来使社会受益。研究人员通过Phanerozoic开发了一个全球弧形碰撞数据库，该数据库标志着前海盆的关闭，并通过最先进的古地理模型重建了其位置。该分析的结果表明，在热带地区，弧形碰撞的最大全球范围与植物学中每个主要冰川时期的发生之间存在时间巧合。研究人员将在五个关键带中完善地质限制和构造重建。通过这些案例研究，研究人员将产生热量数据，并完善新几内亚的发掘历史，并构建一种新的古地理模型，用于在高山 - 山层带中缝合。研究人员还将从墨西哥到南美，阿巴拉契亚北部的奥多维奇缝合线以及阿拉伯 - 纽约尼比亚诺比亚盾牌的Neopereroteroic suterures沿泛氧化的缝合线沿碳纤维（墨西哥到南美洲的铜）缝合线获得新的地层，地质，地质，质学，地球化学和古磁数据。这些现场和实验室数据将与古地理，风化和气候模型集成，以开发使用Geoclim模型框架在热带地区弧形碰撞导致的PCO2变化的估计。该框架将以不同PCO2的气候模型与全球风化模型集成在一起，从而可以使用可变气候来估计全球气候性模型变化对长期稳态PCO2水平的影响。在此框架中，研究人员将执行灵敏度测试，以隔离特定参数（例如岩性或地形）的影响。研究人员将通过现代和古蛇状石流域中的源阳离子研究进一步校准这些模型。最后，他们将开发统计方法来评估相关强度，并测试假设的因果机制，以实现环境变化。通过这项研究，研究人员将直接培训一名博士后研究员，5名博士生和众多本科研究助理。为了传播这项基础研究，团队将与K-12老师一起举办公开研讨会和讲习班，并在在线课程材料上构建有关构造和气候的课程，包括在线课程材料，并在高中和本科级别上建立了校园。这奖反映了NSF的法定任务，并通过使用该基金会的知识优点和广泛的影响来评估NSF的法定任务，并被认为是值得的。