Collaborative Research: Integrating Fluorspar Ages and Geophysical Models to Constrain the Timing and Mechanisms of the Collapse of the Cordillera in SW North America

合作研究：整合萤石年龄和地球物理模型来约束北美西南部科迪勒拉山脉塌陷的时间和机制

• 批准号: 2317871
• 负责人: Paul Tomascak
• 金额: $ 9.09万
• 依托单位: SUNY College at Oswego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317871&HistoricalAwards=false
• 关键词: Collaborative; Research; Integrating; Fluorspar; Ages

About 60 million years ago Southwestern North America was a mountain belt with the length of the Himalayas and height of the Andes. These mountains collapsed under their own load starting about 30 million years ago, ending in the classic Basin and Range province that exists in the region today. The geological history of this collapsing mountain belt is also connected with the formation of deposits of minerals critically necessary for the security and maintenance of the economic well-being of the United States. The research team will test the hypothesis that fluids flowing through the crust were key to the collapse through the dating of fluorspar deposits that are geographically associated. These deposits themselves are a critical mineral resource. The research will use innovative dating methods to estimate the time of formation of the fluorite and associated minerals and compare this with the time of collapse of the highlands. The timing for the emplacement of these deposits will provide key information for proposed numerical simulations of the processes. Previous geophysical studies have provided three-dimensional imaging of the Earth’s interior for the region that will also be used to inform and test the numerical simulations, and these geophysical studies will be updated to better aid the simulations. The computer simulations will also contribute to a better understanding of the sources and magnitudes of tectonic forces responsible for earthquakes in the region, contributing to a better seismic hazard assessment. The project involves a collaborative plan to engage a diverse undergraduate and graduate student population with all components of laboratory, computational, and field work. Outstanding questions remain about the thermomechanical processes involved in the extensional collapse of the North American Southwest Cordillera, including the evolution of thermal input, crustal fluids and melts, topographic change, and plate tectonic and mantle flow evolution. Low upper mantle seismic wave speeds, together with active volcanism, are insufficient to predict rapid lithospheric strain rates in the southwestern US. Instead, in addition to the slow upper mantle wave speeds and volcanism, the lithosphere is characterized by abundant geothermal waters, enriched in F and 3He (indicating mantle fluid sources), which predicts rapid lithospheric strain. Belts of fluorspar deposits, which are associated with highly extended zones, are therefore likely to be precipitates of paleofluids emplaced during times of rapid transtensional crustal strain. The proposed work will test this hypothesis by using U/Pb and (U–Th)/He dating combined with a high-resolution time-dependent thermomechanical model. Furthermore, 40Ar/39Ar dating of associated sericite and alunite deposits will provide validation and confidence in the fluorite dating methods. Thermomechanical model outputs will be compared with geologic, thermochronologic, sedimentologic, and geophysical observations. The proposed thermochemical modeling will 1) quantify the causes and consequences of the topographic changes of the study area by modeling the collapse of the Nevada-plano and Arizona-plano; 2) identify the mechanisms for lithospheric weakening, including the role of thermal and magmatic evolution; 3) provide direct tectonic context for deformation and seismic hazards within the modern Basin and Range Province; and 4) integrate the latest seismic results from the Earthscope project by incorporating seismic, thermal, and compositional information of the lithosphere-asthenosphere system. Metamorphic core complex formation is hypothesized to be linked to collapse of highlands, but to date no 3-D models have directly addressed the effects of body forces set up by realistic topography. Methods developed for this proposal are poised to address the physics of the development of the core complexes as well as the structural evolution of the Basin and Range in the context of the inferred timing of rheological weakening informed by fluorspar dating. The novel approach to dating fluorspar, together with the integrated thermomechanical modeling plan, can be applied to other regions of the world where fluorspar deposits are associated with extensional zones. The proposed work involves a collaborative plan to integrate a diverse undergraduate and graduate student population with all components of laboratory, computational, and field work. The collaboration involves colleagues and students from Suffolk Community College, Kingsborough Community College, SUNY Oswego, Columbia University, and Stony Brook University. The integrated work will engage under-represented minority undergraduate students and will train the next generation of geoscientists in an exciting interdisciplinary effort. Students will be engaged every summer in training seminars, and will be involved in laboratory work, computational geodynamic modeling using Python and Jupyter Notebooks, and field preparation, training, and field work. Outreach efforts will culminate in short courses at GSA and AGU on communicating science to a broader audience. This collaborative work explores the cutting-edge linkage between critical mineral formation and the 3-D evolution of the dynamics of Southwest Cordillera.This project is jointly funded by the Frontier Research in Earth Systems Program and the Division of Earth Sciences to support projects that increase research capabilities, capacity and infrastructure at a wide variety of institution types, as outlined in the GEO EMBRACE DCL.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.

大约6000万年前，北美西南部是一条山带，是喜马拉雅山的长度和安第斯山脉的高度。这些山脉从大约3000万年前开始以自己的负担倒塌，结束于当今该地区存在的经典盆地和山脉省。这种倒塌的山带的地质历史还与矿物质的矿床的形成有关，这是对美国经济福祉的安全和维护所必需的。研究团队将检验以下假设：通过与地理位置相关的氟富矿石的约会，流过外壳的笛子是崩溃的关键。这些存款本身是关键的次要资源。这项研究将使用创新的约会方法来估计氟石和相关矿物质的形成时间，并将其与高地崩溃的时间进行比较。这些沉积物的安置的时机将为提议的流程数值模拟提供关键信息。先前的地球物理研究为该地区的地球内部提供了三维成像，这些成像也将用于告知和测试数值模拟，这些地球物理研究将进行更新以更好地帮助模拟。计算机模拟还将有助于更好地理解该地区地震的构造力量的来源和幅度，从而有助于更好的地震危害评估。该项目涉及一项协作计划，以与实验室，计算和现场工作的各个组成部分一起参与不同的本科生和研究生群体。关于北美西南山脉涉及的热机械过程的出色问题，包括热输入，地壳流体和熔体的演变，地形变化以及板块构造和地幔流动的演变。高地幔地震波速度以及活跃的火山症，不足以预测美国西南部的快速岩石圈应变速率。取而代之的是，除了缓慢的地幔速度和火山效应外，岩石圈还具有丰富的地热水，富含F和3HE（指示的地幔液来源），该水预测了快速的岩石圈菌株。因此，与高度扩展区域相关的氟矿床带可能是在快速tranStensal稳定性时期扩展的古流体的珍贵。提出的工作将通过使用U/PB和（U – Th）/He日期结合使用高分辨率时间依赖性热机械模型来检验这一假设。此外，相关的葡萄石和铝制沉积物的40AR/39AR年代将提供验证和信心对氟矿的约会方法。热机械模型的输出将与地质学进行比较，提出的热化学建模将通过对研究区域的地形变化的原因和后果进行比较。 2）确定岩石圈弱化的机制，包括热和岩浆进化的作用； 3）为现代盆地和山脉省内的变形和地震危害提供直接的构造背景； 4）通过将岩石圈 - 亚赛圈系统的地震，热和复合信息结合到Earthscope项目中的最新地震结果。假设变态核心复合物的形成与高地的崩溃有关，但是迄今为止，没有3-D模型直接解决了由现实的地形所建立的身体力的影响。为该提案开发的方法被毒死，以解决核心复合物发展的物理学以及盆地的结构演变和在推断的流变学时弱化时机的背景下，由荧光素约会所告知。约会荧光灯的新方法，以及集成的热机械建模计划，可以应用于世界其他区域，在该地区，氟富集矿床与扩展区域相关。拟议的工作涉及一项协作计划，旨在将潜水员的本科和研究生群体与实验室，计算和现场工作的所有组成部分相结合。合作涉及萨福克社区学院，金斯伯勒社区学院，纽约州立大学奥斯威戈，哥伦比亚大学和斯托尼·布鲁克大学的大学。综合工作将吸引代表不足的少数族裔本科生，并将在令人兴奋的跨学科工作中训练下一代的地球科学家。每年夏天，学生将参与培训半少数，并将使用Python和Jupyter笔记本，以及现场准备，培训和现场工作。外展工作将在GSA和AGU的简短课程中达到顶峰，以向更广泛的受众传达科学。 This collaborative work explores the cutting-edge linkage between critical minor formation and the 3-D evolution of the dynamics of Southwest Cordillera.This project is jointly funded by the Frontier Research in Earth Systems Program and the Division of Earth Sciences to support projects that increase research capabilities, capacity and infrastructure at a wide variety of institution types, as outlined in the GEO EMBRACE DCL.This award reflects NSF's statutory mission and has been使用基金会的智力优点和更广泛的影响标准，认为通过评估被认为是宝贵的支持。