Mantle Circulation Constrained (MC2): A multidisciplinary 4D Earth framework for understanding mantle upwellings

地幔环流约束 (MC2)：用于理解地幔上升流的多学科 4D 地球框架

• 批准号: NE/T012595/1
• 负责人: James Wookey
• 金额: $ 80.12万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT012595%2F1
• 关键词: Mantle; Circulation; Constrained; MC2; multidisciplinary; Mantle; Circulation; Constrained; MC2; multidisciplinary

The theory of plate tectonics revolutionised the Earth sciences and had impacts across society, by providing a framework to understand the motion of Earth's surface. However, plate tectonic theory does not tell us about the processes deeper in the Earth that drive plate motions, nor does it explain some of the most dramatic events in Earth history: the breakup of plates and outpouring of huge volumes of lava. The next required breakthrough is to make this leap, from a 2D description of plates to understanding the truly 4D nature of Earth's interior processes.Motion of the Earth's interior, its circulation, involves both upwelling and downwelling. The upwelling flow in the Earth remains enigmatic, occurring in the present-day as both hot focused plumes, which are only just observable through modern seismic imaging techniques, and a hypothesised diffuse flow, which has evaded detection entirely. A third mode of mantle upwelling is currently dormant, making its mantle flow signature unknown. However, this dormant mode of flow drives massive outpourings of lava, and has been associated with continental breakup and mass extinction events.Our project's overall goal is to constrain how mantle upwellings operate within the Earth. We will investigate how plate tectonics is linked to mantle circulation, by combining the history of plate movements across Earth's surface with observations drawn from across the geosciences, and use these to constrain state-of-the-art 4D computational models of mantle flow.These advances are made possible by recent progress in disciplines from across the Earth sciences, expertise we bring together here in geodynamics, seismology, geomagnetism, geochemistry, petrology, and thermodynamics. We will constrain present mantle flow by gathering new seismic imaging data of the Earth's deep interior. We will constrain past mantle flow using newly collected data on the mantle's composition, past magnetic field, and the history of Earth's surface uplift. We will use these multidisciplinary approaches to generate the most spatially and temporally complete set of observational constraints on mantle circulation yet assembled.These observations will be used to constrain and improve models that calculate mantle circulation in an Earth-like 3D geometry, driven by plate motion histories (mantle circulation models, MCMs). This is a timely development capitalising on the only recently available record of plate motion over 1 billion years of Earth History. The MCMs predict the mantle's temperature, density, and velocity through time, providing a 4D model of the Earth. Uncertain inputs in these models such as mantle viscosity and composition will be investigated within the bounds provided by the project's geochemical and thermodynamic work packages that will develop new models of Earth's high pressure mineralogy and physical properties. We will test the present-day predictions of the MCMs by converting model outputs to predict density and material properties within the Earth, using our developments on mineral physics modelling. With these inputs and constraints, we will create the first accurate computational models of mantle circulation over the last 1 billion years, which will provide dynamical insight into what drives the diversity of upwellings in the Earth.

板块构造理论通过提供一个框架来了解地球表面运动的框架，彻底改变了地球科学，并在整个社会上产生了影响。但是，板块构造理论并未告诉我们地球上驱动板运动的过程更深，也没有解释地球历史上最戏剧性的事件：板块的破裂和大量熔岩的大量。下一个必需的突破是从板的2D描述到理解地球内部过程的真正4D性质。地球内部的动力，其循环涉及上升和下降。地球上的上升流仍然存在着神秘性，在当今时期发生，这两种热聚焦羽都只能通过现代地震成像技术观察到，而假设的弥漫性流量完全避免了检测。目前，第三种地幔上升流的模式处于休眠状态，这使得其地幔流签名未知。然而，这种休眠的流动方式驱动了熔岩的大量浇灌，并且与大陆分裂和大规模灭绝事件有关。 We will investigate how plate tectonics is linked to mantle circulation, by combining the history of plate movements across Earth's surface with observations drawn from across the geosciences, and use these to constrain state-of-the-art 4D computational models of mantle flow.These advances are made possible by recent progress in disciplines from across the Earth sciences, expertise we bring together here in geodynamics, seismology, geomagnetism, geochemistry,岩石学和热力学。我们将通过收集地球深内部的新的地震成像数据来限制目前的地幔流。我们将使用在地幔的组成，过去的磁场和地球表面隆起的历史上的新收集的数据来限制过去的地幔流。我们将使用这些多学科方法来生成迄今为止组装的地幔循环的最完整的观察性约束。这些观察结果将用于约束和改进模型，这些模型在板循环模型，MCMS，MCMS，MCMS中，计算地球样3D几何的地幔循环。这是一项及时的发展，利用了超过10亿年地球历史的唯一可用的板块运动记录。 MCM可以随着时间的推移预测地幔的温度，密度和速度，提供了地球的4D模型。这些模型中的不确定输入（例如地幔粘度和成分）将在该项目的地球化学和热力学工作包提供的范围内研究，这些范围将开发出地球高压矿物质学和物理特性的新模型。我们将通过将模型输出转换为预测地球内的密度和材料特性，利用我们在矿物质物理建模上的发展来测试MCM的当今预测。借助这些输入和约束，我们将在过去10亿年内创建第一个准确的地幔循环计算模型，这将提供动态的见解，以了解驱动地球上下落多样性的原因。