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.

板块构造理论指出，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而坚固的，而板块分开的海洋边界（大洋中脊）则薄、热且脆弱。与板块构造理论的标准预期相反，观察发现洋中脊的部分经常从弱边界移动或跳跃到强板块内部。因此，大洋中脊的跳跃可以改变构造板块的大小和形状，甚至当它们跳跃到大陆区域时会形成微大陆（大陆物质的小碎片）。据信，大洋中脊的跳跃是在某些过程削弱了附近板块内部之后造成的。 然而，科学家们并不知道这种减弱背后的原因或驱动力。先前的研究以二维几何结构研究了洋中脊跃变，但无法解决控制其形成的几个关键过程，从而在我们对板块构造的理解中留下了空白。 在这项研究中，创新实验室和最先进的 3D 数值模拟将用于隔离导致洋中脊跳跃的过程。了解这些过程将增进对地球热演化以及与过去热液活动相关的潜在矿产资源位置的了解。该职业奖的教育部分有两个主要目标：1) 激励年轻学生（~10-18 岁）通过基于海洋地质学的互动视频游戏进行基于 STEM 的探究，这些游戏具有吸引力、娱乐性且易于提供深入探索海洋地质主题的机会，2) 让多个跨学科本科生小组参与实践、参与的体验，学习 STEM 技能并探索海洋地质数据。对众多遗迹传播中心和海洋地质数据的观察由脊轴突然迁移或跳跃形成的微大陆表明，大洋中脊的跳跃经常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跃的过程，从而检验脊跳跃形成存在可预测的长度和时间尺度的假设。该目标分为三个目标，旨在量化：1）岩浆增生在与已建立的山脊相邻的新生裂谷的传播以及随后形成的转换断层或重叠扩张中心中的作用； 2）地幔柱引起的大洋岩石圈脊跳跃； 3）跃入大陆岩石圈形成微大陆。这些目标将通过 3D 数值模拟和使用胶体流体的创新实验室实验来实现。为了从这些模型和实验中建立可检验的预测，结果将用于推导洋脊跳跃的长度和时间尺度与可观测量（例如扩张速率、洋脊迁移速率、海底年龄和熔体通量）之间的函数关系。这些关系将通过与新的跳跃统计数据库进行比较来评估，其中包括跳跃距离、最终段长度、变换故障或重叠扩展中心形成率和位置，以及重复跳跃之间的时间。该奖项反映了 NSF 的法定使命，并被视为值得通过使用基金会的智力优点和更广泛的影响审查标准进行评估来支持。