CAREER: Moving into the 3rd Dimension: Quantifying the influence of Magmatism, Tectonics, Hydrothermal Cooling, and Hotspots on the Dynamic Evolution of Divergent Plate Boundaries

职业：进入第三维度：量化岩浆作用、构造、热液冷却和热点对发散板块边界动态演化的影响

• 批准号: 1753354
• 负责人: Eric Mittelstaedt
• 金额: $ 59.96万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753354&HistoricalAwards=false
• 关键词: CAREER; Moving; into; 3rd; Dimension

The theory of plate tectonics states that the surface of the Earth is made up of numerous moving plates. The interior regions of these plates are believed to be rigid and strong, while boundaries in the ocean where the plates spread apart, mid-ocean ridges, are thin, hot, and weak. In contrast to the standard expectations of plate tectonic theory, observations find that sections of mid-ocean ridges often shift, or jump, from weak boundaries to strong plate interiors. As a result, jumps of mid-ocean ridges can change the size and shape of the tectonic plates and even create micro-continents (small slivers of continental material) when they jump into continental regions. Mid-ocean ridge jumps are believed to result after some process weakens a nearby plate interior. However, scientists do not know the reasons or driving forces behind this weakening. Previous studies examined mid-ocean ridge jumps in a 2D geometry, but could not address several key processes that would control their formation, leaving a gap in our understanding of plate tectonics. In this study, innovative laboratory and state-of-the-art 3D numerical simulations will be used to isolate the processes that lead to mid-ocean ridge jumps. Understanding these processes will improve understanding of the thermal evolution of the planet and the locations of potential mineral resources associated with past hydrothermal activity. The educational component of this CAREER award has two primary goals: 1) to motivate young students (~10-18 years old) to pursue STEM-based inquiry through interactive, marine geology-based video games that are engaging, entertaining, and provide easily accessible opportunities for in-depth exploration of marine geology topics, and 2) to involve several interdisciplinary groups of undergraduate students in a hands-on, engaging experience where they learn STEM skills and explore marine geologic data.Observations of numerous relic spreading centers and micro-continents formed by sudden relocations or jumps of ridge axes indicate that mid-ocean ridge jumps regularly shift to new, off-axis locations. This project's primary research goal is to quantify the processes that govern ridge jumps and thereby test the hypothesis that there are predictable length- and time-scales for ridge jump formation. This goal is split into three objectives that aim to quantify: 1) the role of magmatic accretion in propagation of nascent rifts adjacent to established ridges and consequent formation of transform faults or overlapping spreading centers; 2) mantle plume-induced ridge jumps in oceanic lithosphere; and 3) micro-continent formation by jumps into continental lithosphere. These objectives will be addressed with 3D numerical simulations and innovative laboratory experiments using colloidal fluids. To establish testable predictions from these models and experiments, results will be used to derive functional relationships between length- and time-scales of ridge jumps and observable quantities such as spreading rate, ridge migration rate, seafloor age, and melt flux. These relationships will be evaluated through comparison to a new database of jump statistics including jump distance, final segment length, transform fault or overlapping spreading center formation rate and location, and the time between repeat jumps.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.

板块构造理论认为，地球表面是由许多移动的板块组成的。这些板块的内部区域被认为是坚硬和坚固的，而板块分开的海洋边界，即大洋中脊，是薄的，热的，脆弱的。与板块构造理论的标准预期相反，观测发现，大洋中脊的部分经常从弱边界转移或跳跃到强板块内部。因此，洋中脊的跳跃可以改变构造板块的大小和形状，甚至在它们跳跃到大陆区域时创造微型大陆（大陆材料的小碎片）。大洋中脊跳跃被认为是在某些过程削弱了附近的板块内部之后产生的。 然而，科学家们不知道这种减弱背后的原因或驱动力。以前的研究在二维几何结构中研究了大洋中脊跳跃，但无法解决控制其形成的几个关键过程，这在我们对板块构造的理解中留下了空白。 在这项研究中，创新的实验室和最先进的三维数值模拟将被用来隔离导致洋中脊跳跃的过程。了解这些过程将有助于更好地了解地球的热演化以及与过去热液活动有关的潜在矿产资源的位置。该职业奖的教育部分有两个主要目标：（1）激励青年学生（~10-18岁）通过互动的，基于海洋地质学的视频游戏进行基于STEM的探究，这些游戏具有吸引力，娱乐性，并为深入探索海洋地质学主题提供了方便的机会，2）让几个跨学科的本科生小组参与实践，对许多遗迹扩散中心和由突然迁移或脊轴跳跃形成的微大陆的观察表明，洋中脊跳跃定期转移到新的离轴位置。这个项目的主要研究目标是量化的过程，支配脊跳跃，从而测试的假设，有可预测的长度和时间尺度脊跳跃形成。这一目标分为三个目标，旨在量化：1）岩浆增生的作用，在传播的新生裂谷附近建立的山脊和随之而来的形成转换断层或重叠的扩张中心; 2）地幔柱引起的洋岩石圈的山脊跳跃;和3）微大陆的形成跳跃到大陆岩石圈。这些目标将通过三维数值模拟和使用胶体流体的创新实验室实验来解决。为了从这些模型和实验中建立可检验的预测，结果将被用来推导出海脊跳跃的长度和时间尺度与可观测量（如扩张率、海脊迁移率、海底年龄和熔体通量）之间的函数关系。这些关系将通过与新的跳跃统计数据库进行比较来评估，包括跳跃距离、最后段长度、转换断层或重叠扩展中心形成速率和位置以及重复跳跃之间的时间。该奖项反映了NSF的法定使命，并且通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。