Integrating Marine Seismic and Ocean Drilling Results with three-dimensional dynamic models of Subduction Initiation

将海洋地震和海洋钻探结果与俯冲起始的三维动态模型相结合

基本信息

批准号：
2049086
负责人：
Michael Gurnis
金额：
$ 35.16万
依托单位：
California Institute of Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-01-01 至 2024-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049086&HistoricalAwards=false
关键词：
Integrating Marine Seismic Ocean Drilling

项目摘要

This project seeks to better understand a process called subduction. Subduction is where cold oceanic plates return to Earth’s interior. Plate subduction is a key geological process responsible for the largest forces on tectonic plates, the site of the most destructive earthquakes on the planet and leads to much of the volcanism on Earth’s surface. The project will look at the process of forming a new subduction zone, which is called subduction initiation. Subduction initiation is poorly understood but is associated with the largest changes in the forces which both drive and resist plate tectonic motions. Although many aspects of plate tectonics are understood, subduction initiation remains a key unknown and there has been a concerted effort in the last few years to understand this process through marine geological and geophysical research. This project will synthesize the recent marine research with what are called plate tectonic reconstructions and incorporate that information into computational models. Some of the key evidence that constrains the process has come from deep sea drilling and through marine seismic surveys. These data constrain the details of the geological evolution and present-day structure of the sites of subduction initiation, respectively. The project will focus on four sites of recent or on-going subduction initiation: Izu-Bonin Mariana south of Japan, Tonga Kermadec in the southwest Pacific, Puysegur south of New Zealand and Matthews-Hunter near Fiji also in the southwest Pacific. It has recently been discovered through ocean drilling that the Izu-Bonin-Mariana and the Tonga-Kermadec subduction zones may have initiated at the same time despite being separated by several thousand miles and were associated with a major change in the motion of the Pacific Plate. This project will look at the details of how these subduction zones formed in terms of the basic physics of solid and fluid mechanics. During subduction initiation, the so-called mega thrust fault, the site of destructive great earthquakes, forms. It is thought that such a new megathrust is in the process of forming south of New Zealand. In this project sophisticated computational methods, call finite elements, will be used and will use the largest supercomputers supported by the National Science Foundation. During the project, a graduate student will be trained in computational methods, which are widely applicable to many areas of science and engineering. The investigator will work with the Caltech Seismo Lab Outreach and Social Media office to communicate science to the broad, diverse community of the Los Angeles community, including through visits to local public schools. The initiation of new subduction zones is a key component of plate tectonics but remains an unsolved problem. With subducted slabs being the primary force driving plate motions, formation of new subduction zones and demise of existing ones are associated with the largest changes in the forces on tectonic plates. There was an ocean basin-wide tectonic change in the Pacific at about 50 Ma with initiation of IBM and Tonga-Kermadec synchronous with a change in plate motions. This project will squarely address these fundamental problems by exploiting the recently expanded observational record from deep sea drilling and marine seismic surveys. The team of geoscientists will test concepts for the initiation of subduction by comparing observations against a new generation of 3D, time-dependent geodynamic models. With the observational constraints on subduction initiation through ocean drilling and marine seismic surveys jumping forward over the last six years simultaneous with a commensurate maturing of software and computational hardware, the time is ideal to readdress the mechanics of subduction initiation. The investigators will build detailed regional plate tectonic reconstructions (data models) for four western Pacific subduction initiation events: Izu-Bonin Mariana (IBM), Tonga Kermadec, Puysegur and Matthews-Hunter. The Puysegur subduction zone (offshore New Zealand) is an ideal natural laboratory for testing the mechanics of subduction initiation with its well-constrained plate kinematics, structural controls, stress evolution, vertical motions, and distribution of faults. These reconstructions provide essential initial and boundary conditions and allow for rigorous comparisons between geodynamic models and geological and geophysical observations. The finite element method will be used for the solution of these inherently time-dependent, multi-scale problems and achieve the resolutions required to track the localization of deformation key for systems with plastic failure. The visco-elastoplastic models will have thermal and compositional buoyancy and explicit sub-scale models of weakening, dislocation creep, and partial melting. The team will constrain, slab strength, stress propagation, plastic failure and fault zone nucleation (weakening mechanisms associated with grain evolution and sperpentinization) from time-dependent models with plate motions for Puysegur since 15 Ma and Matthews-Hunter since 2 Ma. The team will determine the conditions needed to initiate the IBM arc at 52 Ma over 100-1,000 km of strike such that the initial magmatic signal is synchronous within a few Myrs. For IBM, the rate at which driving forces grow and are transmitted to the Pacific plate will be addressed. The project will reach a new level of integration between dynamic flow models, plate kinematics and MG&G data that could have broad application. The work could impact several large programs. The geodynamic hypotheses could result in predictions that could be tested with deep sea drilling under the auspices of IODP.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.

该项目旨在更好地理解一个称为俯冲的过程。俯冲是冷海板回到地球内部的地方。板块俯冲是负责构造板上最大力的关键地质过程，构造板是地球上最具破坏性地震的地点，并导致地球表面上的大部分火山症。该项目将研究形成新的俯冲带的过程，该过程称为俯冲计划。俯冲计划的理解很差，但与驱动和抵抗板块构造运动的力的最大变化有关。尽管了解了板块构造的许多方面，但俯冲倡议仍然是一个未知的关键，并且在过去几年中，通过海洋地质和地球物理研究进行了一致的努力，以了解这一过程。该项目将将最近的海洋研究与所谓的板块构造重建合成，并将这些信息纳入计算模型。限制该过程的一些主要证据来自深海钻井和海洋地震调查。这些数据分别限制了俯冲倡议地点的地质演化和当前结构的细节。该项目将重点关注最近或正在进行的俯冲倡议的四个地点：日本南部的伊祖·邦宁·玛丽安娜（Izu-Bonin Mariana），西南太平洋地区的汤加·凯尔马德（Tonga Kermadec），新西兰南部的普伊西格尔（Puysegur）和西南太平洋地区斐济附近的马修斯·亨特（Matthews-Hunter）也在西南太平洋地区。最近，通过海洋钻探发现了Izu-Bonin-Mariana和Tonga-kermadec俯冲带可能在同一时间启动了几千英里的目的地，并且与太平洋板块运动的重大变化有关。该项目将研究这些俯冲区如何根据固体和流体力学的基本物理学形成的细节。在俯冲启动期间，所谓的巨型推力断层，破坏性的大地震的所在地，形成。人们认为，如此新的大型巨像正在新西兰南部形成。在这个项目中，将使用Call有限元素的复杂计算方法，并将使用国家科学基金会支持的最大超级计算机。在项目期间，研究生将接受计算方法的培训，这些方法广泛适用于许多科学和工程领域。调查人员将与加州大学Seismo实验室外展和社交媒体办公室合作，将科学传达给洛杉矶社区的广阔，潜水社区，包括通过访问当地公立学校。新的俯冲带的倡议是板块构造的关键组成部分，但仍然是一个未解决的问题。由于俯冲板是主要的力量驾驶板运动，因此形成了新的俯冲带和现有的灭亡区与构造板上力的最大变化有关。 Pacific的海洋盆地范围内发生了大约50 mA的构造变化，IBM和Tonga-Kermadec同步启动，板块运动发生了变化。该项目将通过利用深海钻孔和海洋地震调查的最近扩展的观察性记录来直接解决这些基本问题。地球科学家团队将通过比较新一代的3D，时间依赖的地球动力学模型来测试俯冲倡议的概念。通过海洋钻探和海洋地震调查对俯冲计划的观察性约束，在过去的六年中，与软件和计算硬件的相应成熟时，人们可以向前迈进，因此现在是理想的时机，是阅读俯冲倡议的机制。研究人员将建立四个西太平洋俯冲倡议事件的详细区域板块构造重建（数据模型）：Izu-Bonin Mariana（IBM），汤加·凯马德克（Tonga Kermadec），普伊塞格尔（Puysegur）和马修斯·亨特（Matthews-Hunter）。 Puysegur俯冲带（新西兰海上）是一个理想的天然实验室，用于测试其俯冲倡议机制，其板板运动板运动学，结构控制，应力演化，垂直运动和断层分布。这些重建提供了必不可少的初始和边界条件，并允许对地球动力学模型以及地质和地球物理观测的严格比较。有限元方法将用于解决这些固有时间依赖的多尺度问题的解决方案，并实现跟踪塑性故障系统的变形键所需的分辨率。 Visco - 弹性塑料模型将具有弱化，脱位蠕变和部分熔化的热浮力和明确的亚尺度模型。该团队将通过时间依赖性模型来限制，平板强度，应力传播，塑性失败和断层区成核（与晶粒进化和蜘蛛静脉化相关的机制弱化的机制），自25个MA以来，Puysegur的板块运动具有Puysegur的板块运动。该团队将确定在52 MA启动IBM ARC超过100-1,000公里的罢工中所需的条件，以使最初的岩浆信号在几点MYR中是同步的。对于IBM，将解决驱动力增长并传输到太平洋板块的速率。该项目将在动态流模型，板运动学和MG＆G数据之间达到新的集成水平，这些数据可能具有广泛的应用。这项工作可能会影响几个大型计划。地球动力学假设可能会导致预测，可以通过IODP的主持下的深海钻探进行测试。该奖项反映了NSF的法定任务，并通过使用该基金会的知识分子优点和更广泛的影响来评估NSF的法定任务。