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

Hofmeister/Yuen研究人员建议对热导率（k）的压力（P），温度（T）和成分-结构（X）依赖性进行为期三年的合作研究，以阐明可能的反馈机制和地幔中的羽流稳定性。目前的光谱模型的k（T，P，X），基于经典阻尼谐振子，再现可用的测量的基本特征。 光谱模型将作如下改进：（1）考虑了发射光对频率的依赖关系，使k辐射分量的理论更加精确。杂质（含水物质，Fe 2+和Fe 3+）将集中在，因为它们的振动和电子吸收大大修改黑体曲线。 (2)在T和P的红外和可见光谱将获得地幔候选相。 (3)该模型将以使用激光闪光技术获得的k（T）为基准：这种方法避免了以前遇到的实验困难。地球动力学模型，包括k（T，P，X）将独立约束的类比与对流实验的胶体，有一个强烈的非线性扩散系数，通过与意大利物理小组合作进行这些实验室研究。 地球动力学数值模拟中的问题包括：（1）岩石圈和板块动力学的机制如何受到k与流变学的相互作用的影响，以及（2）可变k和相变是否可以诱导分层对流，延迟核幔系统的长期冷却，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。 由于非线性扩散影响深远，具有基础性质，该小组计划向地球科学以外的学科教育机构传播关于非线性扩散影响的研究结果。

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.