CSEDI: Thermal conductivity of lower mantle minerals and heat flow across the core/mantle boundary

CSEDI：下地幔矿物的热导率和穿过核/地幔边界的热流

• 批准号: 0969033
• 负责人: Abby Kavner
• 金额: $ 34.6万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0969033&HistoricalAwards=false
• 关键词: CSEDI; Thermal; conductivity; lower; mantle

The heat flow across the Earth's core-mantle boundary controls the thermal evolution of the whole Earth, which is ultimately expressed on the surface by plate tectonics. However the thermal properties of the core/mantle boundary are not well known, leading to significant uncertainties in our understanding of the temperature and heat profile of the Earth - both currently and in the past. The goal of this proposal is to determine the thermal properties -especially thermal conductivity- of the Earth's mantle, through a combination of experiment and modeling. This information will be used to help constrain the temperature profile throughout the Earth's interior, the style of mantle convection, and the timing for the growth of the inner core. We will combine methods from theoretical and experimental mineral physics and heat flow modeling in crystalline bulk and in composite materials to measure the thermal conductivity of the deep Earth. Starting with a data set describing the lattice thermal conductivity of MgO and MgSiO3 at deep mantle conditions, we will measure how the presence and behavior of iron changes those values at high pressures and temperatures. The experimental data will be interpreted with help from computational models of heat flow in the laser-heated diamond cell, used to make these measurements. Finally, we examine the implications for the mantle using a heat flow model for composite materials and including both conduction and radiation. The overall outcome will be an estimate of the thermal conductivity of the lower mantle at core/mantle boundary conditions, and how the thermal conductivity varies with pressure, temperature, and composition. This project brings together two scientists from very different disciplines: a mechanical engineer with expertise in heat transfer and a geophyscist with expertise in measurements of physical properties under extreme conditions. This interdisciplinary project will support the training of a graduate student for three years. In addition, this project will support summer research for undergraduates at UCLA. Measurements of thermal properties of materials under extreme conditions are important not only for Earth & planetary science, but also for engineering, materials science, and physics. Both researchers are actively involved in science education and outreach at all levels, and have active research groups including undergraduate and graduate students, and postdoctoral scholars.

穿过地球核幔边界的热流控制着整个地球的热演化，并最终通过板块构造在地表表现出来。 然而，地核/地幔边界的热特性并不为人所知，这导致我们对地球温度和热量分布的理解存在很大的不确定性-无论是现在还是过去。该提案的目标是通过实验和建模相结合来确定地球地幔的热特性，特别是热导率。这些信息将被用来帮助限制整个地球内部的温度分布，地幔对流的风格，以及内核生长的时间。 我们将结合联合收割机的方法，从理论和实验矿物物理学和热流模型在晶体块和复合材料，以测量地球深部的导热率。 从描述MgO和MgSiO 3在深地幔条件下的晶格热导率的数据集开始，我们将测量铁的存在和行为如何在高压和高温下改变这些值。实验数据将被解释的帮助下，从计算模型的热流在激光加热的金刚石细胞，用于使这些测量。 最后，我们研究的影响，地幔使用复合材料的热流模型，包括传导和辐射。总体结果将是在核/幔边界条件下地幔热导率的估计，以及热导率如何随压力，温度和成分而变化。该项目汇集了两名来自不同学科的科学家：一名具有传热专业知识的机械工程师和一名具有极端条件下物理特性测量专业知识的地球物理学家。这个跨学科项目将支持研究生的培训三年。 此外，该项目将支持加州大学洛杉矶分校本科生的夏季研究。 在极端条件下测量材料的热性质不仅对地球行星科学很重要，而且对工程，材料科学和物理学也很重要。两位研究人员都积极参与各级科学教育和推广活动，并拥有活跃的研究小组，包括本科生和研究生以及博士后学者。