Radiative Thermal Conductivity of Upper Mantle and Transition Zone Minerals

地球内部的结构和动力学在很大程度上取决于热流，因此也取决于其组成部分的导热性。地幔材料（如橄榄石）的热导率与温度和压力有关，是地幔对流地球动力学模型的一个重要参数。热导率变化影响岩石圈地热模式、俯冲动力学和岩石圈板块结构。410至660公里深度之间的地幔过渡带是否在地球上地幔和下地幔中起着热通量调节器的作用？上地幔和过渡带矿物的热导率约束较差，热导率辐射部分的实验数据很少，特别是在这些地区存在的高压和高温下。本实验研究旨在补充不断发展的理论框架，将正在进行的项目扩展到地幔的所有主要成分，并使用原位光谱学作为强大的工具间接测量辐射导热系数的温度-压力变化。该项目的一个主要目标是进一步了解自然界的主要驱动力——地球内部的热流。该项目建立在最近的原位光学测量基础上，首次同时进行高压和高温测量，研究了两个主要的过渡带阶段，含水瓦德斯莱岩和含水环伍德岩。我们报道了大的辐射热导率，这揭示了红外和可见光谱范围内的能量传输“窗口”。我们发现地幔过渡区可能对辐射传热有显著的贡献，我们证实了水化可能会增加辐射热通量的预测。目前的项目将把这些研究扩展到橄榄石、多数石和d相。此外，我们计划系统地研究成分变化（如铁和水的浓度）对橄榄石及其高压多晶wadsleyite和ringwoodite导热性能的影响。这项研究是高度协作的性质，并将利用全国各地实验室的专业知识和设施，以及国际上，特别是华盛顿卡内基研究所的地球物理实验室（光学测量），西北大学的地球与行星科学和土木与环境工程系（光谱学）以及波茨坦亥姆霍兹中心- GFZ德国地球科学研究中心（合成）。这项工作将阐明一个广泛的受众，包括矿物物理学家、地震学家、地球动力学家、地球化学家和行星科学家，深切关注的基本跨学科主题。我们的研究将为本科生提供宝贵的学习经验，以及重要的数据，这将有助于我们了解地球的传热？这将有助于改进地球热通量的地球物理模型。

Structure and dynamics of our planet's interior depend crucially upon heat flow and thus upon the thermal conductivity of its constituents. Temperature- and pressure-dependent thermal conductivity of Earth's mantle materials, such as olivine, is an important parameter for geodynamic models of mantle convection. Thermal conductivity variations affect models of lithospheric geotherms, subduction dynamics, and the structure of lithospheric slabs. Does the mantle transition zone between a depth of 410 and 660 km act as a heat flux regulator within the Earth's upper and lower mantle? Thermal conductivities of upper mantle and transition zone minerals are poorly constrained, and there is little experimental data on the radiative part of thermal conductivity, especially at the high pressures and temperatures that exist in those regions. This experimental study aims to complement continually evolving theoretical frameworks, extend ongoing projects to all major constituents of the Earth's mantle and indirectly measure temperature-pressure variation of radiative thermal conductivity using in-situ optical spectroscopy as powerful tool. A primary goal of the project is to further our understanding of a major driving force of nature - heat flow within the Earth. This project builds upon recent in-situ optical measurements, for the first time at simultaneous high-pressure and high-temperature, studying two major transition zone phases, hydrous wadsleyite and hydrous ringwoodite. We reported large radiative thermal conductivities, which reveal an energy transmission 'window' in the infrared and visible spectral range. We found that the mantle transition zone may contribute significantly to radiative heat transfer, and we confirmed predictions that hydration may enhance radiative heat flux. The current project will extend those studies to olivine, majorite, and phase D. In addition, we plan to systematically study the effect of compositional changes (such as iron and water concentrations) on thermal conductivity properties of olivine and it's high-pressure polymorphs wadsleyite and ringwoodite. This research is of highly collaborative nature, and will take advantage of the expertise and facilities of laboratories across the nation, as well as internationally, in particular the Geophysical Laboratory of the Carnegie Institution of Washington (optical measurements), the Earth and Planetary Science and Civil and Environmental Engineering departments at Northwestern University (spectroscopy) and the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences (syntheses). This work will illuminate a fundamentally interdisciplinary topic of deep concern to a broad audience, including mineral physicists, seismologists, geodynamicist, geochemists, and planetary scientists. Our study will provide a valuable learning experience for undergraduate students, as well as important data, which will contribute to our knowledge of heat transfer in the Earth?s interior and will help to improve geophysical models of heat flux in the Earth.