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

这项提议的最终目标是从根本上修正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。这个公认的具有挑战性的目标是由最近广泛领域的发展所推动的，这些发展指出了当前普遍观点的不足，即地幔动力学主要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”的冷却发生的。新的地震层析反演3-D地幔结构的工作，结合了地球动力学和矿物物理学的限制，加上最近在核心-地幔边界（CMB）的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，显示了地球上最活跃的洋脊系统（东太平洋隆起）的横向稳定性，这些都表明，目前的标准模型充其量是不完整的。因此，迫切需要建立一个修正的地幔对流模型来满足这些新发现。因此，我提出了一个涉及“自下而上”方法的研究计划，包括地幔的整个深度范围。这项工作将集中于若干目标：(1)地幔层析成像——显著提高太平洋下地幔三维结构的分辨率，在那里预测了大规模的热地幔物质上涌；(2)热演化——了解源自CMB的热羽状物中强烈的向上热输送如何影响地球内部的演化；(3)数据同化——获得高分辨率；(4)板块构造演化——发展具有复杂流变学的最先进的地幔对流模型，从而产生与下伏地幔动态耦合的自一致板块。这项建议的最重要目标之一是培训高素质的人员。它们的参与将是这一努力的关键组成部分，目的是对我们星球内部动力的运作建立一种全面的新观点。

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.