EAR-PF: Unravelling climate and tectonic signatures using a landscape evolution modelling framework to interpret stable isotope and thermochronology records

EAR-PF：使用景观演化建模框架来解释稳定同位素和热年代学记录，揭示气候和构造特征

• 批准号: 2204585
• 负责人: Rachel Havranek
• 金额: $ 18万
• 依托单位: Havranek, Rachel E
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204585&HistoricalAwards=false
• 关键词: EAR; PF; Unravelling; climate; tectonic

When geologists use rocks to go back in time to understand what Earth was like in the past, it can be challenging to pull apart the competing effects of climate and tectonics (i.e. mountain building). For example, in the Northern Patagonian Andes, the scientific community has previously noted observations that indicate the region got colder and drier during the Miocene Epoch. But, it is hard to know if that apparent cold climate is because the Northern Patagonian Andes were at high elevations in the Miocene (causing the local climate to be cold) or if the local environment was responding to changes in global climate. There are two major portions of this postdoctoral fellowship. In the first part, PI Havranek will use three different geochemistry tools, all of which were developed in the last 15 – 20 years, that can each shed light on different aspects of the climate and tectonics system of the Northern Patagonian Andes in the Miocene. Because the tools PI Havranek intends to use are so new, the interpretation of these kinds of data has always been done separately from each other. To be able to interpret them together, PI Havranek will create a landscape evolution model. These kinds of models are intended to describe the ways that landforms (like mountain ranges) change through time. The model will be capable of predicting what the geochemical data should be based on different hypothesized climate and tectonic scenarios. Then it is possible to evaluate which hypothesis best fits all of the geochemical data. The final goal of this project is to shed light on which came first, a cold climate that enabled the growth of the Northern Patagonian Andes, or the uplift of a mountain range that locally cooled the climate. If successful, this kind of approach could be extended to different places around the world. As a part of the field work associated with this project, PI Havranek will lead a short course on stable isotope geochemistry for students at Universidad de La Plata. To make both the field sites and laboratory settings used for this project more accessible, PI Havranek will produce a series of video tours of those spaces. Two high-school students, recruited through the University of Idaho Upward Bound TRIO-INSPIRE program will help assess the videos and make them accessible to a wide range of viewers.The geoscience community has long recognized that climate and tectonics are inextricably linked and feedback on each other via erosion and landscape evolution. Over geologic timescales, tectonics can modulate climate through silicate weathering, and climate can influence deep-crustal processes by controlling the extent of weathering and erosion. It is particularly challenging to disentangle the primary driver, climate or tectonics, of observations in the rock record. For example, if a paleoenvironment cooled over time, that cooling could be driven by either surface uplift or by cooling of the global climate. Many of the proxy tools geochemists have developed to target questions about climate and tectonics target either past climatic conditions or rates of rock exhumation. Furthermore, geochemical proxy data are frequently interpreted in isolation to independently constrain either climatic and tectonic histories without considering their concurrent evolution. In this project, the aim is to co-interpret the climatic and tectonic history of the Paso del Sapo Basin in the Northern Patagonian Andes (Chubut Province, Argentina). The Paso del Sapo basin in the Broken Foreland of the Argentine Andes provides a unique opportunity to develop a framework for integrating thermochronology, stable isotope geochemistry, and landscape evolution modeling because there is a well-documented geologic context, and clear, testable tectonic and climatic hypotheses exist. PI Havranek will create a record of 1) paleoclimate using carbonate clumped isotope thermometry and volcanic glass stable isotope geochemistry and 2) exhumation using low temperature thermochronology (detrital apatite (U-Th)/He). Then, PI Havranek will create a landscape evolution model capable of predicting both stable isotope geochemistry and low temperature thermochronology data. This model will be used to test previously proposed tectonic and climatic hypotheses of the Paso del Sapo Basin. This project would provide a proven framework for future coupled stable isotope and thermochronology studies. The project will support: 1) the implementation of a stable isotope geochemistry short course at Universidad de La Plata; 2) the creation of accessible geoscience education videos; and 3) mentorship of two high school students through the University of Idaho TRIO-INSPIRE Upward Bound Program.This project is jointly funded by the Earth Sciences Postdoctoral Fellowship program and the Established Program to Stimulate Competitive Research (EPSCoR).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.

当地质学家使用岩石来追溯时间以了解地球过去的样子时，将气候和构造（即造山运动）的竞争影响分开可能具有挑战性。例如，在北方巴塔哥尼亚安第斯山脉，科学界以前注意到的观察表明，该地区在中新世时期变得更冷，更干燥。但是，很难知道这种明显的寒冷气候是因为北方巴塔哥尼亚安第斯山脉在中新世处于高海拔地区（导致当地气候寒冷），还是当地环境对全球气候变化做出了反应。这个博士后奖学金有两个主要部分。在第一部分中，PI Havranek将使用三种不同的地球化学工具，所有这些工具都是在过去15 - 20年中开发的，每一种工具都可以揭示中新世北方巴塔哥尼亚安第斯山脉气候和构造系统的不同方面。由于PI Havranek打算使用的工具是如此的新，这些类型的数据的解释一直是分开进行的。为了能够一起解释它们，PI Havranek将创建一个景观演变模型。这类模型旨在描述地貌（如山脉）随时间变化的方式。该模型将能够预测地球化学数据应该基于不同的假设气候和构造情景。然后就可以评估哪种假设最适合所有的地球化学数据。这个项目的最终目标是阐明哪一个先来，是寒冷的气候使北方巴塔哥尼亚安第斯山脉得以生长，还是山脉的隆起使气候局部变冷。如果成功的话，这种方法可以推广到世界各地。作为与该项目有关的实地工作的一部分，PI Havranek将为拉普拉塔大学的学生开设一个关于稳定同位素地球化学的短期课程。为了使该项目使用的现场和实验室设置更容易访问，PI Havranek将制作一系列这些空间的视频图尔斯。通过爱达荷州大学的Upward Bound TRIO-INSPIRE项目招募的两名高中生将帮助评估这些视频，并使它们能够被广泛的观众访问。地球科学界长期以来一直认识到，气候和构造是密不可分的，并通过侵蚀和景观演变相互反馈。在地质时间尺度上，构造可以通过硅酸盐风化来调节气候，而气候可以通过控制风化和侵蚀的程度来影响地壳深部的过程。要解开岩石记录中观测结果的主要驱动因素，即气候或构造，尤其具有挑战性。例如，如果一个古环境随着时间的推移而变冷，那么这种变冷可能是由地表抬升或全球气候变冷所驱动的。地球化学家开发的许多替代工具针对气候和构造问题，目标要么是过去的气候条件，要么是岩石折返的速度。此外，地球化学代用数据往往被孤立地解释，以独立地约束气候和构造历史，而不考虑它们的同步演化。本项目的目的是共同解释北方巴塔哥尼亚安第斯山脉（阿根廷丘布特省）帕索德尔萨波盆地的气候和构造历史。位于阿根廷安第斯山脉断裂前陆的帕索德尔萨波盆地提供了一个独特的机会，可以开发一个整合热年代学、稳定同位素地球化学和景观演化建模的框架，因为这里有一个有据可查的地质背景，并且存在清晰、可检验的构造和气候假设。PI Havranek将创建1）使用碳酸盐凝块同位素测温法和火山玻璃稳定同位素地球化学的古气候记录，以及2）使用低温热年代学（碎屑磷灰石（U-Th）/He）的剥露记录。然后，PI Havranek将创建一个能够预测稳定同位素地球化学和低温热年代学数据的景观演化模型。该模型将被用来测试以前提出的构造和气候假设的帕索德尔萨波盆地。该项目将为今后的稳定同位素和热年代学耦合研究提供一个经过验证的框架。该项目将支持：（1）在拉普拉塔大学开设稳定同位素地球化学短期课程;（2）制作可供使用的地球科学教育录像;以及3）通过爱达荷州大学TRIO-INSPIRE向上拓展计划指导两名高中生。该项目由地球科学博士后奖学金计划和刺激竞争性研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。