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

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。洪水玄武岩是地球上火山活动最广泛的表现。这些巨大岩浆的喷发和侵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1400万年前它们喷发时的脱气影响了全球气温。理解岩浆系统的一个关键方面是破译岩浆是如何从深处运往地表的。在俄勒冈州的首席约瑟夫堤群，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。虽然这些岩浆的运移机制已被很好地了解(即，片状岩浆作用)，但岩浆作用的样式和时间限制很少。也就是说，首席约瑟夫岩脉是通过单脉冲事件产生的，还是随着时间的推移以一系列岩浆脉冲的形式增长的，其中每个岩浆脉冲都对构造变形和脱气做出了贡献？详细了解运移和侵位机制可以限制岩浆作用过程中地表变形和挥发分释放的速度。这项研究将利用相对快速、简单和资源光的方法，通过详细研究岩墙本身中记录的晶体结构来了解岩墙的侵位和生长机制。该团队的研究项目从一开始就被设计为为未被充分代表的少数族裔(URM)本科生提供无与伦比的研究体验，他们将被招募参与研究和传播过程。这项研究旨在通过促进未来STEM研究和教育学生的未来领导者和导师的发展，为使地球科学成为一个多样化、公平和包容性的学科做出贡献。该计划将使URM学生群体受益，他们拥有知识、动机和灵感，以追求专注的科学职业，以解决美国-国家和全球的挑战。该项目将研究哥伦比亚河洪水玄武岩(CRFB)的构造-岩浆演化，如首席约瑟夫堤群(CJDS)中所记录的那样。该团队将开发和传播一种使用电子背向散射衍射(EBSD)的技术，通过质地分析来识别堤防侵位风格。对堤防中心的分析将在具有统计意义的数量的堤防上进行，以有意义地限制单事件和脉冲式侵位风格的实际比例。堤防中心的纹理分析将使用现场观测和跨堤坝收集的详细纹理剖面的子集进行校准，以确定整体冷却历史。拟议工作产生的信息将解决围绕着产生空间以容纳数百至数千个平均厚度相当大的堤坝的长期存在的问题。这将对未来的研究产生影响，因为它将生成一个关于岩墙结构和形态的详细数据库，以便将来与CRFB的其他岩墙群系统进行比较，并与世界各地的其他岩墙群进行交叉比较。这些结果将为深入了解岩浆在地壳中的运移效率以及构造和岩浆活动之间的关系提供依据。对持续高雷诺数流动的岩脉或岩脉脉冲组合的结构进行表征，将有助于我们全面了解岩浆管道系统及其与矿化带和热液场的联系。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代表不足的少数民族(URM)学生研究科学家。该项目将扩大URM在地球科学领域的参与，因为我们将充分利用佐治亚州历史上黑人学院和少数族裔服务机构的现有学生群体。该计划将使URM学生群体受益，他们拥有知识、动机和灵感，以追求专注的科学职业，以解决美国-国家和全球的挑战。更重要的是，这项研究是故意建立的，以使地球科学成为一门多样化、公平和包容的学科。他们的指导经验建立在创造一个受欢迎的环境和相关导师的全面指导和学术社交的基础上，这些已被证明是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人才。要做到这一点，研究人员需要努力在他们计划研究的方式上进行变革性的改变。该团队认为，他们的项目设计努力为地球科学领域带来正义、多样性和包容性。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.