Contraining the large-scale dynamics and structure of the lower mantle using observations of the geoid, dynamic topography and plate tectonics

利用大地水准面、动态地形和板块构造的观测来约束下地幔的大尺度动力学和结构

基本信息

批准号：
1645245
负责人：
Shijie Zhong
金额：
$ 35.5万
依托单位：
University of Colorado at Boulder
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-01-01 至 2020-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1645245&HistoricalAwards=false
关键词：
Contraining large scale dynamics structure

项目摘要

Analyzing seismic waves traveling through the inside of the Earth has revealed that the Earth's mantle has a predominately long-wavelength (5000 km) structure. Particularly, the lower mantle beneath the circum-Pacific regions has seismic wave speeds that are relatively fast, while seismic wave speeds in the lower mantle beneath Africa and Pacific are relatively slow. These two seismically slow areas beneath Africa and the Pacific are are considered anomalies, and are most likely hot regions within the mantle because seismic waves travel slower in hot materials. These anomalies are particularly strong near the boundary between the core and mantle (Core-Mantle Boundary or CMB) regions, and are often termed as large low shear-velocity provinces or LLSVPs. The LLSVPs encompass most volcanism and large igneous provinces for the last 200 million years. This pattern in mantle seismic structure also highly correlates with the gravity anomalies at the Earth's surface. Together with seismic studies, geochemical studies also suggest that the LLSVPs may be compositionally different from the bulk of the mantle, being enriched in heavy, incompatible elements such as radioactive elements U and Th. Considering the significant influence of volcanic degassing on Earth's climate and the important effect of mantle viscosity on post-glacial rebound and sea-level change, it is therefore important to understand the dynamics of the long-wavelength mantle convection, the generation of the LLSVPs, and the relationship between the LLSVPs and their surface expression including volcanism and gravity anomalies. The goal of this 3-year project is to seek understanding of these fundamental questions, by analyzing and modeling fluid dynamical processes of mantle convection. This project will also lead to significant improvement in computational techniques in modeling mantle convection via international collaboration with an Australian geodynamicist. The project includes training of a graduate student. The project seeks to address the following three specific questions: 1) Are the LLSVPs purely thermal or thermochemical features? 2) Can the observations of the geoid and dynamic topography be made consistent with stable, thermochemical LLSVPs? 3) Can the long-wavelength mantle structure and convection (e.g., degree-2) be generated dynamically self-consistently with dynamic plates and realistic lithospheric rheology including the low-temperature plasticity? Four tasks for the proposed three-year project include: 1) to seek buoyancy and viscosity structures that explain the geoid, CMB excess ellipticity, and stability of the chemically distinct LLSVPs, by formulating mantle flow models with buoyancy derived from seismic models with compositional effects from the LLSVPs and post-perovskite phase change; 2) to test the hypothesis that the LLSVPs are purely thermal or thermochemical anomalies, using time-dependent convection models with imposed plate motion history; 3) to understand the origin of long-wavelength mantle structures including the LLSVPs, by formulating fully dynamic models of mantle convection with realistic lithospheric rheology; 4) to improve solvers in CitcomS for efficiency and robustness. The project should significantly improve understanding on the origins of the LLSVPs, long-wavelength mantle convection and plate tectonics. The results should have direct implications for studies in other areas beyond geodynamics, including mantle geochemistry, seismology, supercontinent cycles, gravity anomalies, and volcanism.

分析穿过地球内部的地震波表明，地幔主要具有长波长（5000 公里）结构。特别是环太平洋地区下地幔的地震波波速较快，而非洲和太平洋地区下地幔的地震波波速相对较慢。非洲和太平洋下方的这两个地震慢区被认为是异常区域，并且很可能是地幔内的热区域，因为地震波在热物质中传播较慢。这些异常在地核和地幔之间的边界（核地幔边界或 CMB）区域尤其强烈，通常被称为大的低剪切速度省或 LLSVP。 LLSVP 涵盖了过去 2 亿年来的大多数火山活动和大型火成岩省。地幔地震结构的这种模式也与地球表面的重力异常高度相关。与地震研究一起，地球化学研究还表明，LLSVP 的成分可能与地幔主体不同，富含重的不相容元素，例如放射性元素 U 和 Th。考虑到火山脱气对地球气候的重大影响以及地幔粘度对冰期后回弹和海平面变化的重要影响，因此了解长波长地幔对流的动力学、LLSVP的产生、以及 LLSVP 与其表面表现（包括火山活动和重力异常）之间的关系。这个为期三年的项目的目标是通过分析和模拟地幔对流的流体动力学过程来寻求对这些基本问题的理解。该项目还将通过与澳大利亚地球动力学家的国际合作，显着改进地幔对流建模的计算技术。该项目包括培养一名研究生。该项目旨在解决以下三个具体问题：1）LLSVP 是纯粹的热特征还是热化学特征？ 2) 大地水准面和动态地形的观测能否与稳定的热化学 LLSVP 一致？ 3）长波长地幔结构和对流（例如，2度）能否与动态板块和包括低温塑性在内的现实岩石圈流变学动态自洽地产生？拟议的三年项目的四项任务包括：1）通过从具有成分效应的地震模型中导出浮力来制定地幔流模型，以寻求浮力和粘度结构，以解释大地水准面、CMB超椭圆率和化学上不同的LLSVP的稳定性来自 LLSVP 和后钙钛矿相变； 2）使用具有板块运动历史的瞬态对流模型来检验LLSVP纯粹是热或热化学异常的假设； 3）通过建立具有真实岩石圈流变学的地幔对流全动态模型，了解包括LLSVP在内的长波长地幔结构的起源； 4) 改进 CitcomS 中的求解器以提高效率和鲁棒性。该项目将显着提高对 LLSVP 起源、长波长地幔对流和板块构造的认识。这些结果应该对地球动力学以外的其他领域的研究产生直接影响，包括地幔地球化学、地震学、超大陆旋回、重力异常和火山活动。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Controls on Global Mantle Convective Structures and Their Comparison With Seismic Models

全球地幔对流结构的控制及其与地震模型的比较

DOI：
10.1029/2019jb017918
发表时间：
2019-08-01
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
0
作者：
W. Mao;S. Zhong
通讯作者：
S. Zhong

Lateral Motion of Mantle Plumes in 3‐D Geodynamic Models

三维地球动力学模型中地幔柱的横向运动

DOI：
10.1029/2018gl081404
发表时间：
2019-05-15
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
Mingming Li;S. Zhong
通讯作者：
S. Zhong

Modeling the Inception of Supercontinent Breakup: Stress State and the Importance of Orogens

模拟超大陆分裂的开始：应力状态和造山带的重要性

DOI：
10.1029/ 2019gc008538
发表时间：
2019-10
期刊：
Geochemistry geophysics geosystems
影响因子：
3.5
作者：
Huang; C.
通讯作者：
C.

The source location of mantle plumes from 3D spherical models of mantle convection

根据地幔对流 3D 球形模型确定地幔柱的源位置

DOI：
10.1016/j.epsl.2017.08.033
发表时间：
2017-11
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
Li, Mingming;Zhong, Shijie
通讯作者：
Zhong, Shijie

Modeling the Inception of Supercontinent Breakup: Stress State and the Importance of Orogens

DOI：
10.1029/2019gc008538
发表时间：
2019-11-01
期刊：
Geochemistry
影响因子：
3.7
作者：
Chuan Huang;Nan Zhang;Zheng‐Xiang Li;M. Ding;Z. Dang;A. Pourteau;S. Zhong
通讯作者：
S. Zhong

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Shijie Zhong其他文献

On the breakup frequency of bubbles and droplets in turbulence: A compilation and evaluation of experimental data

关于湍流中气泡和液滴的破碎频率：实验数据的汇编和评估

DOI：
发表时间：
2023
期刊：
International Journal of Multiphase Flow
影响因子：
3.8
作者：
Shijie Zhong;R. Ni
通讯作者：
R. Ni

Elution-extrusion counter-current chromatography separation of five bioactive compounds from Dendrobium chrysototxum Lindl.

洗脱-挤出逆流色谱分离金皮石斛中五种生物活性化合物。

DOI：
10.1016/j.chroma.2011.03.015
发表时间：
2011-05-20
期刊：
Journal of chromatography. A
影响因子：
0
作者：
Shucai Li;Shichao He;Shijie Zhong;Xingmei Duan;Haoyu Ye;Jie Shi;A. Peng;Li
通讯作者：
Li

Constraints of the topography, gravity and volcanism on Venusian mantle dynamics and generation of plate tectonics

地形、重力和火山作用对金星地幔动力学和板块构造生成的制约

DOI：
10.1016/j.epsl.2012.11.051
发表时间：
2013
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
Jinshui Hunag;An Yang;Shijie Zhong
通讯作者：
Shijie Zhong

Modification strategies for non-aqueous, highly proton-conductive benzimidazole-based high-temperature proton exchange membranes

非水、高质子传导苯并咪唑基高温质子交换膜的改性策略

DOI：
10.1016/j.cclet.2023.109261
发表时间：
2023-10-01
期刊：
Chinese Chemical Letters
影响因子：
9.1
作者：
Yunfa Dong;Shijie Zhong;Yuhui He;Zhezhi Liu;Shengyu Zhou;Qun Li;Yashuai Pang;Haodong Xie;Yuanpeng Ji;Yuanpeng Liu;Jiecai Han;W. He
通讯作者：
W. He