Collaborative Research: Interactions Between the Tonga-Lau Subduction System and the Samoan Plume

合作研究：汤加-劳俯冲系统与萨摩亚地幔柱之间的相互作用

• 批准号: 1928914
• 负责人: Douglas Wiens
• 金额: $ 25.3万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1928914&HistoricalAwards=false
• 关键词: Collaborative; Research; Interactions; Between; Tonga; Collaborative; Research; Interactions; Between; Tonga

A fundamental goal of solid earth science is to improve our understanding of the Earth’s interior evolution, which is driven by mantle convection. There are three primary components of the mantle convection system: 1) subduction where one tectonic plate (slab) descends into the Earth’s interior along an oceanic trench, 2) plate spreading at mid-ocean ridges where the majority of seafloor is created, and 3) buoyant upwelling, or mantle plumes, where hot and less dense materials rise from the deep earth to the surface to create volcanoes like the Hawaiian islands. Locations where these three systems interact—including the Tonga oceanic trench, Lau back-arc spreading centers, and Samoa volcanic islands—provide unique opportunities to investigate these competing mechanisms. In this study, the juxtaposition of the Samoan plume and the northern edge of the Tonga-Lau subduction system is used to investigate mantle flow in a slab-plume setting, and to understand how the distinctive compositional and thermal characteristics of plume materials are distributed. The project provides training for graduate and undergraduate students and a postdoctoral investigator.An interdisciplinary project, consisting of seismic imaging, geochemical analysis of submarine lavas, and geodynamic modeling, is used to investigate the Tonga-Lau-Samoa system. Seismic observations will be obtained from an 18-month deployment of 30 Ocean Bottom Seismographs (OBSs) and 5 land seismometers (including 3 permanent stations) in the northern Tonga-Lau and Samoa regions. Several different seismic imaging techniques will provide 3-D velocity models of the upper mantle, precise earthquake locations will image the slab tear and associated deformation, and the variation of seismic velocity with direction will provide constraints on mantle flow. Lava samples will be dredged at 10 seamount locations east of the Tonga Trench to better understand subduction inputs into the northern Tonga Trench with the goal of understanding the distribution of enriched mantle material in the Lau Basin. The samples will be analyzed for isotopic compositions allowing identification of possible sources of non-Samoan hotspot materials in the Lau Basin, which is critical for geochemical interpretations of mantle flow. A series of geodynamic models will simulate slab-plume interactions with a variety of possible configurations. Using the integrated history of time-dependent mantle flow in the models, the predicted thermal structure and mantle textures can be directly compared with seismic and geochemical observations.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.

固体地球科学的一个基本目标是提高我们对地球内部进化的理解，这是由地幔连接驱动的。地幔连接系统的三个主要组成部分：1）俯冲，其中一个构造板（平板）沿着海沟沿着地球内部降落到地球内部，2）板块在海底的大部分海脊中散布在一起，在那里产生了大部分海底，而3）浮力浮出水面，或者在地面上散发出较小的山水，沿着地面繁殖，以象征着近地的水平，从而呈现了近地的茂密散发，从而呈现出茂密的景象。这三个系统相互作用的位置（包括汤加海洋沟渠，LAU背面蔓延中心和萨摩亚火山群岛）提供了研究这些竞争机制的独特机会。在这项研究中，使用萨摩亚羽流的并置和汤加洛俯冲系统的北边缘来研究在平板盘环境中的地幔流，并了解如何分布李子材料的独特组成和热特性。该项目为研究生和本科生提供了培训，以及博士后研究员。一个跨学科项目，包括地震成像，海底熔岩的地球化学分析和地球动力建模，用于研究汤加 - 洛 - 萨莫阿系统。地震观察将是从北汤加北部和萨摩亚地区的30个海洋底部地震仪（OBS）和5个土地地震仪（包括3个永久驻地）部署的18个月部署。几种不同的地震成像技术将提供上套层的3-D速度模型，精确的地震位置将对平板撕裂和相关的变形进行成像，地震速度与方向的变化将对地幔流提供约束。熔岩样品将在汤加沟以东的10个山丘地点挖出，以更好地理解俯冲的输入到北汤加沟渠中，目的是了解Lau盆地中丰富的地幔材料的分布。将分析样品的同位素组合物，以识别LAU盆地中非soan热点材料的可能来源，这对于地幔流的地球化学解释至关重要。一系列地球动力学模型将使用各种可能的配置模拟平板胶合相互作用。使用模型中时间相关的地幔流的综合历史，可以将预测的热结构和地幔纹理直接与地震和地球化学观测直接进行比较。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准来通过评估来通过评估来获得的支持。