4-D Geodynamic Modeling With Data Assimilation: Origin Of Intra-Plate Volcanism In The Pacific Northwest

带数据同化的 4-D 地球动力学建模：太平洋西北地区板内火山活动的起源

• 批准号: 1516586
• 负责人: Lijun Liu
• 金额: $ 3.81万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1516586&HistoricalAwards=false
• 关键词: Geodynamic; Modeling; Data; Assimilation; Origin

Continental volcanism represents a major natural hazard on Earth. Understanding the formation mechanism of volcanism is of high interest to the scientific community. The proposed work aims to clear out the existing confusions on the interpretation of surface volcanic features, mantle seismic images, and the systems overall evolution with time. This proposed research will be broadly transformative due to its multidisciplinary nature. For example, understanding past mantle evolution will help identify the tectonic origin of variousmantle seismic structures, an important goal of geophysics; a better constrained mantle thermal structure will provide a new context for explaining geochemistry data associated with volcanism; linking plate motion history and mantle dynamics will lead to new insights of surface tectonic deformation, which may provide a new perspective for interpreting geological records. Most importantly, long-term Earth evolution models like the one proposed here will provide a framework for establishing physical connections among different fields of geoscience research and linking dynamic processes occurring at different spatial and temporal scales. Additionally, the proposed research will produce excellent lecture materials for general education. The PI plans to participate in outreach activities such as the iRISE program to deliver K-12 lectures through online teaching. Origin of the Pacific Northwest intra-plate volcanic province, including the mid-Miocene Steens-Columbia River flood basalt and subsequent Yellowstone and Newberry hotspot tracks, still remains heavily debated after decades of research. One popular hypothesis is that this volcanic province formed from a mantle plume originating from the core-mantle boundary region. Alternatively, many models argued for a shallow origin, without involving a mantle plume. However, most of these earlier conceptual models did not consider observational constraints from the mantle, which only became available recently with the help of USArray. The tomography inversions generated from these data reveal unprecedented details on the mantle structure of western U.S., which in turn provide important information on the corresponding mantle dynamics and its temporal evolution over time. These seismic images also present a new perspective on the origin of Pacific Northwest volcanic history. The proposed project will use the Blue Waters supercomputer to quantitatively evaluate the origin of the Pacific Northwest volcanic province by simulating the sub-lithosphere dynamic evolution of western United States in the context of Mesozoic-Cenozoic subduction history of the Farallon plate below North America. The PI proposes to, first, calculate the detailed mantle flow since the Miocene using forward and adjoint methods based on recent seismic tomography and then to explore three hypotheses on the generation of observed slow seismic anomalies and surface volcanism including: 1) a mantle plume in a subduction environment, 2) slab-generated mantle upwelling, and 3) entrainment and intrusion of hot oceanic asthenosphere. High-resolution geodynamic models with realistic initial and boundary conditions will be used to calculate mantle flow and test hypotheses.

大陆火山活动是地球上的主要自然灾害。了解火山作用的形成机制引起了科学界的高度兴趣。这项工作旨在消除对地表火山特征、地幔地震图像和系统随时间整体演化的解释上现有的困惑。由于其多学科性质，这项拟议的研究将具有广泛的变革性。例如，了解过去的地幔演化将有助于识别各种地幔地震构造的构造起源，这是地球物理学的重要目标；更好地约束地幔热结构将为解释与火山活动相关的地球化学数据提供新的背景；将板块运动历史和地幔动力学联系起来将带来对地表构造变形的新见解，这可能为解释地质记录提供新的视角。最重要的是，像这里提出的长期地球演化模型将为在地球科学研究的不同领域之间建立物理联系以及连接不同空间和时间尺度上发生的动态过程提供一个框架。此外，拟议的研究将为普通教育提供优秀的讲座材料。 PI 计划参与 iRISE 计划等外展活动，通过在线教学提供 K-12 讲座。经过数十年的研究，太平洋西北地区板内火山区的起源，包括中新世中期斯廷斯-哥伦比亚河溢流玄武岩以及随后的黄石和纽伯里热点轨迹，仍然存在激烈争论。一种流行的假设是，这个火山省是由源自核心-地幔边界区域的地幔柱形成的。另外，许多模型认为起源较浅，不涉及地幔柱。然而，这些早期的概念模型大多没有考虑来自地幔的观测约束，这些约束最近在 USArray 的帮助下才变得可用。这些数据产生的层析成像反演揭示了美国西部地幔结构前所未有的细节，这反过来又提供了有关相应地幔动力学及其随时间演化的重要信息。这些地震图像还为西北太平洋火山历史的起源提供了新的视角。拟议项目将使用 Blue Waters 超级计算机，通过模拟北美下方法拉隆板块中生代-新生代俯冲历史背景下美国西部岩石圈下的动态演化，定量评估西北太平洋火山省的起源。 PI建议首先使用基于最近地震层析成像的正演和伴随方法计算自中新世以来的详细地幔流，然后探索关于观测到的慢地震异常和地表火山活动的产生的三种假设，包括：1）地幔柱俯冲环境，2）板片产生的地幔上升流，3）热海洋软流圈的夹带和侵入。具有现实初始和边界条件的高分辨率地球动力学模型将用于计算地幔流和检验假设。

项目成果

Abnormal seismological and magmatic processes controlled by the tearing South American flat slabs

南美板块撕裂控制的异常地震和岩浆过程

• DOI: 10.1016/j.epsl.2016.06.019
• 发表时间: 2016-09-15
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Jiashun Hu;Lijun Liu
• 通讯作者: Lijun Liu

High-resolution lithosphere viscosity and dynamics revealed by magnetotelluric imaging

大地电磁成像揭示的高分辨率岩石圈粘度和动力学

• DOI: 10.1126/science.aaf6542
• 发表时间: 2016-09-30
• 期刊: Science
• 影响因子: 56.9
• 作者: Lijun Liu;D. Hasterok
• 通讯作者: D. Hasterok

Subduction-controlled mantle flow and seismic anisotropy in South America

南美洲俯冲控制的地幔流和地震各向异性

• DOI: 10.1016/j.epsl.2017.04.027
• 发表时间: 2017-07-15
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Jiashun Hu;M. Faccenda;Lijun Liu
• 通讯作者: Lijun Liu

Simulation of late Cenozoic South American flat-slab subduction using geodynamic models with data assimilation

使用数据同化的地球动力学模型模拟晚新生代南美平板俯冲

• DOI: 10.1016/j.epsl.2016.01.011
• 发表时间: 2016-03-15
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Jiashun Hu;Lijun Liu;A. Hermosillo;Quan Zhou
• 通讯作者: Quan Zhou