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

板块构造理论认为地球表面是由许多活动的板块组成的。这些板块的内部区域被认为是坚硬而坚固的，而板块分开的海洋边界，即大洋中脊，则是薄、热、弱的。与板块构造理论的标准预期相反，观察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，甚至在它们跳入大陆区域时形成微大陆（大陆物质的小块）。洋中脊跳被认为是由于某些过程削弱了附近的板块内部。然而，科学家们并不知道这种减弱背后的原因或驱动力。之前的研究以二维几何形式考察了海中脊跳，但无法解决控制其形成的几个关键过程，这给我们对板块构造的理解留下了空白。在这项研究中，创新的实验室和最先进的3D数值模拟将用于分离导致洋中脊跳的过程。了解这些过程将提高对地球热演化的理解，以及与过去热液活动相关的潜在矿产资源的位置。CAREER奖的教育部分有两个主要目标：1)激励年轻学生（~10-18岁）通过互动的，基于海洋地质的电子游戏进行基于STEM的探究，这些游戏引人入胜，有趣，并为深入探索海洋地质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，参与体验，学习STEM技能并探索海洋地质数据。对大量因脊轴突然移位或跳跃而形成的遗迹扩张中心和微大陆的观测表明，洋中脊跳有规律地转移到新的离轴位置。该项目的主要研究目标是量化控制脊跳的过程，从而检验脊跳形成的可预测长度和时间尺度的假设。这一目标分为三个目标，旨在量化：1)岩浆增生在靠近已建脊的新生裂谷扩展和随后形成的转换断层或重叠扩张中心中的作用；2)海洋岩石圈地幔柱脊跃；3)跳入大陆岩石圈形成微大陆。这些目标将通过使用胶体流体的3D数值模拟和创新实验室实验来解决。为了从这些模型和实验中建立可测试的预测，结果将用于推导脊跃的长度和时间尺度与可观测量（如扩展速率、脊移速率、海底年龄和熔体通量）之间的函数关系。这些关系将通过与一个新的跳跃统计数据库进行比较来评估，包括跳跃距离、最终段长度、转换断层或重叠扩展中心的形成速度和位置，以及重复跳跃之间的时间。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。

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.