Collaborative Research: How are Flood Basalts Fed? A Textural Investigation of the Chief Joseph Dike Swarm

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。洪水玄武岩是地球上火山活动最广泛的表现形式。这些巨大岩浆的喷发和就位与全球气候变化和许多物种灭绝事件有关。俄勒冈州、华盛顿州、爱达荷州和内华达州的哥伦比亚河洪水玄武岩是这种大规模火山活动的最新和保存最完好的例子。据信，1700万至1400万年前火山喷发期间的脱气影响了全球气温。了解岩浆系统的一个关键方面是破译岩浆是如何从深处输送到地表的。在俄勒冈州的约瑟夫酋长堤群，哥伦比亚河洪水玄武岩的岩浆管道系统的一部分被保存下来并暴露出来。虽然这些岩浆的输送机制（即片状岩浆作用）已被很好地理解，但对岩浆作用的类型和时间却知之甚少。也就是说，首席约瑟夫堤坝是通过单脉冲事件产生的，还是作为一系列岩浆脉冲随着时间的推移而形成的，其中每个脉冲都导致了构造变形和脱气？详细说明运移和侵位机制可以限制岩浆活动期间地表变形和挥发性释放的速率。这项研究将利用相对快速、简单和资源轻的方法，通过详细研究岩脉本身记录的晶体结构，让我们了解岩脉的就位和生长机制。这个团队的研究项目从一开始就被设计为一个无与伦比的研究经验，为未被充分代表的少数民族（URM）本科生，他们将被招募参与研究和传播过程。本研究旨在通过促进STEM研究和教育中未来领导者和导师的发展，为地球科学成为一个多元化、公平和包容的学科做出贡献。该计划将使URM的学生群体受益，他们将获得知识、动力和灵感，追求专注的科学事业，以解决美国国家和全球的挑战。该项目将调查哥伦比亚河洪水玄武岩（CRFB）的构造岩浆演化，该玄武岩记录在酋长约瑟夫堤防群（CJDS）中。该团队将开发并推广一种利用电子反向散射衍射（EBSD）技术，通过纹理分析来识别堤防的就位风格。对堤防中心的分析将在统计上显著的堤防数量上进行，以有意义地限制单事件和脉冲就位风格的实际比例。堤防中心的结构分析将通过现场观测和收集堤防上的详细结构剖面子集进行校准，以确定整体冷却历史。拟议的工作所产生的信息将解决围绕空间产生的长期问题，以容纳数百到数千个平均厚度相当大的堤防。这将影响未来的研究，通过生成一个详细的岩脉结构和形态数据库，将允许未来与其他CRFB岩脉群系统进行比较，并与全球其他岩脉群进行交叉比较。研究结果将有助于了解岩浆在地壳中的输送效率以及构造和岩浆作用之间的关系。描述脉脉脉冲组合或经历持续高雷诺数流动的脉脉的结构特征，将有助于我们对岩浆管道系统及其与矿化带和热液场的联系的整体理解。此外，该项目将与乔治亚州的教育组织建立联系。研究人员将在三年内培训和专业发展六名未被充分代表的少数民族（URM）学生研究科学家。该项目将扩大urm对地球科学的参与，因为我们将充分利用格鲁吉亚传统黑人学院和大学以及少数民族服务机构的现有学生群体。该计划将使URM的学生群体受益，他们将获得知识、动力和灵感，追求专注的科学事业，以解决美国国家和全球的挑战。更重要的是，本研究旨在使地球科学成为一个多样化、公平和包容的学科。他们的指导经验是建立在创造一个友好的环境，由相关的导师和学术社交提供全面的指导，这已被证明是urm的综合工具。他们希望激发URM学生为地球科学带来的非凡的未开发的才能。要做到这一点，科学家需要努力改变他们计划研究的方式。该团队认为，他们的项目设计力求为地球科学领域带来公正、多样性和包容性。该奖项反映了美国国家科学基金会的法定使命，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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Flood basalts are the Earth’s most extensive expressions of volcanism. The eruption and emplacement of these voluminous magmas have been linked to global climate shifts and many extinction events. The Columbia River Flood Basalts in Oregon, Washington, Idaho, and Nevada are the most recent and best-preserved example of this voluminous volcanic activity. It is believed that degassing during their eruption 17-14 million years ago influenced global temperatures. A key aspect to understanding magmatic systems is deciphering how the magma is transported from depth to surface. At the Chief Joseph Dike Swarm in Oregon, a portion of the magmatic plumbing system of the Columbia River Flood Basalts is preserved and exposed. While the transport mechanism for these magmas is well understood (i.e., sheet magmatism), the style and timing of magmatism is poorly constrained. Namely, were the Chief Joseph Dikes produced through single-pulse events or grown through time as a series of magmatic pulses where each of them contributed with tectonic deformation and degassing? Detailing the mechanism of transport and emplacement could constrain the rates of surface deformation and volatile release during magmatism. This study will utilize relatively fast, simple, and resource-light methodologies that will inform us of the dike emplacement and growth mechanisms by studying in great detail the crystal textures recorded in the dikes themselves. This team’s research project was designed from the ground up as an unparalleled research experience for underrepresented minority (URM) undergraduate students who will be recruited to participate in the research and dissemination process. This research is built intentionally to contribute to making the geosciences a diverse, equitable, and inclusive discipline by promoting the development of future leaders and mentors for subsequent students in STEM research and education. The program will benefit the URM student cohorts with the knowledge, motivation, and inspiration to pursue focused science careers to solve US-national and global challenges. This project will investigate the tectonomagmatic evolution of the Columbia River Flood Basalts (CRFB), as recorded within the Chief Joseph Dike Swarm (CJDS). The team will develop and disseminate a technique that uses Electron Backscatter Diffraction (EBSD) to identify dike emplacement style using textural analyses. Analyses of dike centers will be performed on a statistically significant number of dikes to meaningfully constrain the actual proportion of single-event and pulsed emplacement styles. Dike-center textural analyses will be calibrated using field observations and a subset of detailed textural profiles collected across dikes to identify the overall cooling history. The information generated by the proposed work will address long-standing questions surrounding the generation of space to accommodate hundreds to thousands of dikes with considerable average thicknesses. This will impact future research by generating a detailed database of dike textures and morphologies that will allow future comparisons with other CRFB dike swarm systems and cross-comparison with other dike swarms worldwide. Results will provide insights into magma transport efficiency through the crust and the relationship between tectonics and magmatism. Characterizing the textures of pulsed assembly of dikes or dikes that experienced sustained high Reynolds Number flow will add to our overall understanding of magmatic plumbing systems and their connection to mineralization zones and hydrothermal fields. Furthermore, the project will create linkages with education organizations in the state of Georgia. Researchers will train and professionally develop six Underrepresented Minority (URM) student research scientists over three years. The project will broaden the participation of URMs in geosciences as we will fully leverage the existing student populations from Historically Black Colleges and Universities and Minority-Serving Institutions in Georgia. The program will benefit the URM student cohorts with the knowledge, motivation, and inspiration to pursue focused science careers to solve US-national and global challenges. More importantly, this research is built intentionally to make geosciences a diverse, equitable, and inclusive discipline. Their mentoring experience is built around creating a welcoming environment with comprehensive guidance by relatable mentors and academic socialization, which have proven to be integrative tools for URMs. They want to foment the extraordinary untapped talent that URM students bring to geosciences. To do this, researchers need to work towards transformative change in the way they plan their research. This team believes that their program design strives to bring justice, diversity, and inclusion to the field of geoscience.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.