Modelling and Interpreting the Surface Evolution of the Earth in Terms of Mantle Convection: Global Implications of High Heat Flow at the Core-Mantle Boundary

根据地幔对流模拟和解释地球表面演化：核-地幔边界高热流的全球影响

• 批准号: 217272-2013
• 负责人: Forte, Alessandro
• 金额: $ 4.15万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=634071
• 关键词: Modelling; Interpreting; Surface; Evolution; Earth

The ultimate goal of this proposal is a fundamental revision of our current understanding of how convection in Earth's mantle works and how this internal dynamics controls the surface geological evolution of the Earth. This admittedly challenging goal is motivated by recent developments from a wide range of fields that point to deficiencies in the current, widespread view that mantle dynamics is dominantly controlled by the subduction of cold lithosphere and hence that Earth's thermal evolution occurs mainly by 'top-down' cooling. New work on seismic tomographic inversions of 3-D mantle structure, incorporating constraints from geodynamics and mineral physics, coupled with very recent mineral physical results on high heat flow at the core-mantle boundary (CMB), and the latest interpretations of Cenozoic plate motions showing the lateral stability of Earth's most active oceanic ridge system (the East Pacific Rise) indicate that the current standard model is, at best, incomplete. There is therefore a pressing need to develop a revised model of mantle convection capable of satisfying the new findings. I therefore propose a program of research involving a 'bottom-up' approach, encompassing the entire depth-extent of the mantle. This work will focus on a number of objectives: (1) Mantle tomography - to significantly improve resolution of the 3-D structures in the lower-mantle below the Pacific Ocean where large-scale upwellings of hot mantle material have been predicted, (2) Thermal evolution - to understand how the evolution of Earth's interior is affected by strong upward heat transport in thermal plumes originating at the CMB, (3) Data assimilation - to obtain high-resolution, accurate reconstructions of thermal structure and mantle flow over the course of the Cenozoic era, and (4) Plate-tectonic evolution - to develop state-of-the-art mantle convection models with complex rheology that yield self-consistent plates dynamically coupled to underlying mantle. One of the most important objectives of this proposal is the training of highly qualified personnel. Their participation will be a key component of this effort to establish a comprehensive new view of the functioning of our planet's internal dynamics.

这项提议的最终目标是从根本上修改我们目前对地幔对流如何工作以及这种内部动力学如何控制地球表面地质演化的理解。这一公认的挑战性目标的动机是最近的事态发展，从广泛的领域，指出在目前的缺陷，广泛的观点，地幔动力学主要是由冷岩石圈的俯冲控制，因此，地球的热演化主要是由“自上而下”的冷却。三维地幔结构地震层析反演的新工作，结合地球动力学和矿物物理学的限制，加上最近关于核幔边界高热流的矿物物理结果，以及对新生代板块运动的最新解释，显示地球最活跃的洋脊系统的横向稳定性（东太平洋隆起）表明，目前的标准模型充其量是不完整的。因此，迫切需要发展一个能够满足新发现的地幔对流修正模型。因此，我提出了一个方案的研究涉及一个“自下而上”的方法，包括整个深度范围的地幔。这项工作将侧重于若干目标：（1）地幔层析成像-以显著提高对太平洋下地幔三维结构的分辨率，在太平洋下地幔，热地幔物质的大规模上升已被预测，（2）热演化-以了解地球内部的演化如何受到源自CMB的热羽流中强烈的向上热输送的影响，（3）数据同化-获得新生代热结构和地幔流动的高分辨率、精确重建;（4）板块构造演化-发展具有复杂流变学的最先进地幔对流模型，产生与下伏地幔动态耦合的自洽板块。这项建议的最重要目标之一是培训高素质的人员。他们的参与将是这一努力的一个关键组成部分，以建立一个关于我们星球内部动力运作的全面的新观点。