Experimental Investigations of the Dynamics of Thermochemical Boundary Layers in the Mantles of Terrestrial Planets

Manga 0124972类地行星地幔顶部和底部的热边界层和化学边界层之间的热量和质量传递控制着类地行星的化学和地球动力学演化。类地行星顶部岩石圈边界层的动力学受多模式（脆性/韧性）流变行为的支配，例如，地球上的板块构造和火星上不动的岩石圈，这些即使不能完全“理解”，至少也很容易观察到。虽然深部地幔动力学观测较少，但仍有地震学、矿物物理学和地球化学数据对地幔动力学提供了制约。在核幔边界附近，流动可能涉及热边界层和化学边界层。实验室实验在处理涉及多组分对流的问题中可以发挥重要作用，在这些问题中，连续粘度和密度界面上的动力学相互作用决定了流动。研究人员将进行一系列实验室实验，旨在更好地了解地球核幔边界的地幔流动动力学。在拟议的工作过程中，他们将在地幔对流的各个方面建立对热化学边界层更好的基本理解。调查将集中在两类实验上：（1）热化学对流的基础研究，以阐明热传递和穿过化学边界层的流动的耦合，量化穿过粘性界面的夹带率，更好地了解控制热化学羽流形成的动力学。(2)利用受控的大尺度流动作为板块运动影响的替代物，重点研究羽流/板块相互作用。研究人员还计划用理论和三维数值模拟研究来补充他们的实验室实验。对于后者，实验室实验将形成有价值的基准。

Manga0124972Heat and mass transfer across thermal and chemical boundary layers at the top and bottom of the mantles of the terrestrial planets govern the chemical and geodynamic evolution these planets. The dynamics of the top, lithospheric boundary layers of terrestrial planets are dominated by multi-mode (brittle/ductile) rheological behavior, e.g., plate tectonics on Earth and immobile lithosphere on Mars, which are at least readily observed if not completely "understood". Although deep mantle dynamics are less accessible to observation, there are still seismological, mineral physics and geochemical data that provide constraints on mantle dynamics. Near the core-mantle boundary, flow probably involves both a thermal and chemical boundary layer.Laboratory experiments can play an important role in treating problems involving vigorous multi-component convection in which dynamical interactions across continuous viscosity and density interfaces determine the flow. The investigators will carry out a series of laboratory experiments aimed at achieving a better understanding of the dynamics of mantle flow at the Earth's core-mantle boundary. Over the course of the proposed work they will forge a better fundamental understanding of thermochemical boundary layers in all aspects of mantle convection.The investigation will focus on two classes of experiments: (1) Basic studies of thermochemical convection to elucidate the coupling of heat transfer and flow across chemical boundary layers, quantify entrainment rates across viscosity interfaces, and better understand the dynamics controlling the formation of thermo-chemical plumes. (2) Focussed studies of plume/plate interactions using controlled large-scale flow as a proxy for the effects of plate motions. The investigators also plan to complement their laboratory experiments with theoretical and 3-D numerical modeling studies. For the latter, the laboratory experiments will form valuable benchmarks.