CSEDI: Collaborative Research: The Influence of Thermal Conductivity on Stabilization and Feedback in Mantle Convection

EAR-0207198EAR-0207176 Hofmeister/Yen研究人员提议对热导率(K)的压力(P)、温度(T)和成分-结构(X)相关性进行为期三年的合作研究，以揭示可能的反馈机制和地幔中羽流的稳定。目前的k(T，P，X)光谱模型基于经典的阻尼谐振子，再现了现有测量的基本特征。光谱模型将作如下改进：(1)通过考虑发射光对频率的依赖关系，使k的辐射分量的理论更加精确。杂质(含水物种，Fe2+和Fe3+)将被重点关注，因为它们的振动和电子吸收极大地修改了黑体曲线。(2)地幔候选相将获得T和P的红外和可见光光谱。(3)模型将与使用激光闪光技术获得的k(T)进行基准比较：这种方法绕过了以前遇到的实验困难。包含k(T，P，X)的地球动力学模型将通过与执行这些实验室研究的意大利物理小组合作，通过类似于对具有强烈非线性扩散系数的胶体的对流实验来独立地限制。地球动力学数值模拟中的问题包括(1)k与流变学的相互作用如何影响岩石圈和板块动力学的力学，以及(2)变化的k和相变是否可以诱导分层对流、延迟核-地幔系统的长期冷却或稳定地幔流动。地球动力学模拟将揭示哪个变量(T、P、X)对地幔对流的影响最大，从而指导矿物物理实验。该团队计划向地球科学以外的其他学科的教育机构传播关于非线性扩散影响的研究结果，因为它具有深远的、基本的性质。

EAR-0207198EAR-0207176Hofmeister/YuenThe investigators propose a three-year collaborative investigation of the pressure (P), temperature (T), and compositional-structural (X) dependence of thermal conductivity (k) to shed light on possible feedback mechanisms and plume stabilization in the mantle. The current spectroscopic model of k(T,P,X), based on classical damped harmonic oscillators, reproduces the essential features of available measurements. The spectroscopic model will be improved as follows: (1) The theory for the radiative component of k will be made exact by including the dependence of the emitted light on frequency. Impurities (hydrous species, Fe2+ and Fe3+) will be focused on because their vibrational and electronic absorptions greatly modify the black-body curve. (2) IR and visible spectra at T and P will be acquired from mantle candidate phases. (3) The model will be benchmarked against k(T) obtained using the laser flash technique: this method circumvents previously encountered experimental difficulties. Geodynamical models incorporating k(T,P,X) will be independently constrained by analogy with convection experiments on colloids that have a strongly nonlinear diffusion coefficient, through collaboration with an Italian physics group performing these laboratory studies. The issues in geodynamic numerical modeling include (1) how the mechanics of the lithospheric and slab dynamics are affected by the interplay of k with rheology, and (2) whether variable k and phase transitions can induce layered convection, delay secular cooling of the core-mantle system, or stabilize mantle flows. The geodynamic modeling will reveal which variable (T, P, X) has the greatest influence on mantle convection, and thus will guide the mineral physics experiments. The team plans to disseminate findings on the effects of nonlinear diffusion, because of its far-reaching, fundamental nature, to educational institutions in disciplines other than geosciences.