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

地幔中的热传输影响板块构造、火山活动和磁场。材料传递热量的方式随深度、温度和成分的不同而变化。该项目测试氧化铁如何改变地幔中的热传输。构造板块中的氧化富铁岩石俯冲至地幔，并可能在地幔底部富集。在这个项目中，研究人员将进行实验来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层和地幔岩石之间的反应如何因其传输热量的能力而影响地球的动力学。该项目将在密歇根州立大学启用一项新技术，并通过实验和共享研究生和博士后学者培训，在密歇根州和台湾的研究人员之间建立合作。密歇根本科生将了解台湾地质学和地球材料的热特性。地幔硅酸盐的导热性调节地球的动力学。最近的研究调查了铁和压力引起的自旋跃迁对地幔矿物热导率的影响。然而，这些研究仅限于还原成分，例如铁方镁石和富含亚铁的桥锰矿。研究人员将在金刚石砧池中使用超快时域热反射（TDTR）光谱来确定氧化铁-富铁桥锰矿和后钙钛矿的晶格导热系数。他们将分离含铁-铁桥石中压力驱动的自旋配对转变的影响以及铝与三价铁对热传输的影响。密歇根州立大学、密歇根大学和台湾中央研究院之间的合作将结合晶体生长、极高压和温度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智力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.