CAREER: New imaging of mid-ocean ridge systems at the Galápagos triple junction

职业：加拉帕戈斯三重交界处洋中脊系统的新成像

• 批准号: 2143865
• 负责人: Zachary Eilon
• 金额: $ 69.23万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-15 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2143865&HistoricalAwards=false
• 关键词: CAREER; New; imaging; mid; ocean

Seismic imaging of mid-ocean ridge systems at the Galápagos triple junctionA key element of plate tectonics is a ~50,000-km-long volcanic mountain chain circling the globe, where plates continuously separate and magma upwells from the Earth’s interior to cool. This has been understood for more than seventy years, but details of the deep structure of these systems remain unresolved. The problem is that most of these mountain chains lie under miles of water in the middle of the oceans (“mid-ocean ridges”; MORs). Seismological measurements are the main tool for peering tens of kilometres into the planet. This project involves a multi-year placement of ocean-bottom seismometers (OBSs) across and along two of these MORs, at a “triple-junction” location where three of these ridges meet. Seismic signals recorded by these instruments will be used to build 3-dimensional models of the solid Earth deep beneath the MORs. This project includes outreach and training activities. The project will involve high school students and will educate the public by producing films during the expeditions. It will provide research and education opportunities for undergraduate and graduate students through scientific expeditions and classwork. The program will involve early career investigators and generate an open-source manual for planning scientific expeditions at sea. The data will enhance understanding of geohazards and imaging of the entire planet.The ~50,000-km-long global mid-ocean ridge (MOR) system, the factory where 65% of the tectonic plates are generated, is arguably the defining feature of our planet’s surface. Yet, fundamental aspects of oceanic extension remain poorly understood, including the mechanisms driving upwelling at mid-ocean ridges and the origin of fabrics and discontinuities in mature ocean plates. This project involves a multi-year broadband ocean bottom seismometer (OBS) deployment across the Galápagos triple junction, involving two diachronous, overlapping ~40 station arrays spanning 400km along strike and perpendicular to the Pacific-Cocos and Cocos-Nazca spreading centers. Surface and body wave tomographic imaging of these MORs, including measurements of seismic attenuation, scattered phases, and seismic anisotropy will provide unprecedented spatial and methodological coverage of lithospheric and asthenospheric structure. This work will: 1) Test predicted signatures of dynamic upwelling; 2) Image MOR melt, dehydration, and shear structures that may persist in mature lithosphere; 3) Explore the 3-D organization of mantle flow beneath the ridges; 4) Exploit contrasts in spreading rate and ridge migration over underlying mantle to gauge the importance of these parameters on ridge dynamics; 5) Investigate MOR maturation beneath a propagating spreading center. Broader impacts target each stage of the pipeline into research: Outreach will educate and engage the broader public and enhance recruitment of high schoolers into the geoscience major. Training will provide research and education opportunities for undergraduate and graduate students through cruises and classwork. Building a Network of Leaders will establish a skilled cohort of early career investigators, and generate an open-source manual for planning OBS deployments. This experiment will also contribute to the international PacificArray initiative, and provide new data for global and deep mantle tomography.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.

加拉帕戈斯三重连接处洋中脊系统的地震成像板块构造的一个关键要素是环绕地球仪的约50，000公里长的火山山脉，在那里板块不断分离，岩浆从地球内部涌上冷却。这一点已经被理解了70多年，但这些系统的深层结构的细节仍然没有解决。问题是，这些山脉大多位于海洋中间数英里的水下（“洋中脊”; MORs）。 地震测量是深入地球数十公里的主要工具。该项目涉及在其中三个海脊交汇的“三联点”位置，横跨和沿着其中两个海洋地震仪放置多年的海底地震仪。这些仪器记录的地震信号将用于建立MORs下方深层固体地球的三维模型。该项目包括外联和培训活动。该项目将涉及高中学生，并将通过在探险期间制作电影来教育公众。它将通过科学考察和课堂作业为本科生和研究生提供研究和教育机会。该计划将涉及早期职业调查人员，并为海上科学考察计划编制一份开源手册。这些数据将加强对地质灾害的理解和对整个地球的成像。全球海洋中脊（莫尔）系统长约5万公里，是65%的构造板块产生的工厂，可以说是我们地球表面的定义特征。 然而，对海洋伸展的基本方面仍然知之甚少，包括驱动洋中脊上升流的机制以及成熟洋板块结构和不连续性的起源。该项目涉及在加拉帕戈斯三重连接点上部署多年宽带海底地震仪（OBS），包括两个沿走向沿着跨越400 km并垂直于太平洋-科科斯和科科斯-纳斯卡扩张中心的贯穿时间、重叠的约40个台站阵列。这些MORs的面波和体波层析成像，包括地震衰减，散射相位和地震各向异性的测量，将提供前所未有的岩石圈和软流圈结构的空间和方法的覆盖面。这项工作将：1）测试预测的动态上升流的特征; 2）成像莫尔熔融，脱水和剪切结构，可能会持续在成熟的岩石圈; 3）探索地幔流动的3-D组织下的脊; 4）开发的扩张速度和脊迁移在下伏地幔的对比，以衡量这些参数的重要性脊动力学; 5）调查莫尔的成熟下的传播扩展中心。更广泛的影响针对管道进入研究的每个阶段：外联将教育和参与更广泛的公众，并加强对高中生进入地球科学专业的招聘。培训将通过游轮和课堂作业为本科生和研究生提供研究和教育机会。建立一个领导者网络将建立一个熟练的早期职业调查人员队伍，并生成一个开源手册，用于规划OBS部署。这项实验也将有助于国际PacificArray计划，并为全球和深部地幔层析成像提供新的数据。该奖项反映了NSF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。