Collaborative Research: Effects of ferric iron on heat transport in Earth's mantle

地幔中的热传输影响着板块构造、火山活动和磁场。物质传递热量的方式随深度、温度和成分而变化。这个项目测试氧化铁如何改变地幔中的热传递。构造板块中富铁的氧化岩向地幔俯冲，并可能富集于地幔底部。在这个项目中，研究人员将进行实验，以生长含有氧化铁成分的地幔相关晶体。他们将测量这些晶体在高压和高温下的热流。这些结果将使他们能够研究地球大气和地幔岩石之间的反应是如何影响地球动力学的，因为它们具有传输热量的能力。该项目将使密歇根州立大学的一项新技术成为可能，并通过实验和共享研究生和博士后学者培训，建立密歇根州和台湾研究人员之间的合作。本课程将向密西根大学本科生介绍台湾地质及地球材料的热性质。地幔硅酸盐的热导率调节着地球的动力学。近年来研究了铁和压力诱导的自旋转变对地幔矿物热导率的影响。然而，这些研究仅限于还原组分，如铁方长石和富铁的桥菱铁矿。研究人员将在金刚石砧细胞中使用超快时域热反射（TDTR）光谱来确定氧化富铁桥锰矿和后钙钛矿的晶格热导率。他们将分离出压力驱动的自旋对跃迁对含铁-铁的桥菱铁矿的影响，以及铝对铁对热输运的影响。密歇根州立大学、密歇根大学和台湾中央研究院的合作将结合晶体生长、极端高压和高温实验以及热流测量方面的互补专业知识，以测量地幔氧化差异如何影响地幔对流。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Heat transport in Earth’s mantle affects plate tectonics, volcanism, and the magnetic field. How materials carry heat varies with depth, temperature, and composition. This project tests how oxidized iron changes heat transport in the mantle. Oxidized iron-rich rock in tectonic plates subducts to the mantle and may be enriched at the base of the mantle. In this project, researchers will conduct experiments to grow mantle-relevant crystals with compositions including oxidized iron. They will measure heat flow in these crystals at high pressures and temperatures. The results will allow them to examine how reactions between Earth's atmosphere and mantle rock affect the Earth’s dynamics as a consequence of their ability to transport heat. This project will enable a new technique at Michigan State and establish collaboration between researchers in Michigan and Taiwan through experiments and shared graduate student and postdoctoral scholar training. Michigan undergraduate students will be introduced to geology of Taiwan and thermal properties of Earth materials. Thermal conductivity of mantle silicates modulates the Earth’s dynamics. Recent studies have investigated the effects of iron and pressure-induced spin transitions on thermal conductivity in mantle minerals. However, these studies have been limited to reduced compositions such as ferropericlase and ferrous-iron-rich bridgmanite. The researchers will use ultrafast time-domain thermo-reflectance (TDTR) spectroscopy in diamond anvil cells to determine the lattice thermal conductivity of oxidized ferric-iron-rich bridgmanite and post-perovskite. They will isolate the effects of the pressure-driven spin pairing transition in ferric-iron-bearing bridgmanite and effects of aluminum versus ferric iron on heat transport. This collaboration between Michigan State University, the University of Michigan, and the Academia Sinica in Taiwan will combine complementary expertise in crystal growth, extreme high pressure and temperature experiments, and heat flow measurement to measure how differences in oxidation in the mantle impact mantle convection.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.