Thermal conductivity of Fe-bearing post-perovskite in the Earth's lowermost mantle
Thermal conductivity of Fe-bearing post-perovskite in the Earth's lowermost mantle
复制标题
DOI：
10.1016/j.epsl.2020.116466
复制
发表时间：
2020-10
影响因子：
5.3
通讯作者：
Y. Okuda;K. Ohta;Akira Hasegawa;T. Yagi;K. Hirose;S. Kawaguchi;Y. Ohishi
中科院分区：
文献类型：
--
作者：
Y. Okuda;K. Ohta;Akira Hasegawa;T. Yagi;K. Hirose;S. Kawaguchi;Y. Ohishi
后钙钛矿（ppv）是mgsio3在地幔中的最高压力多晶型，其热导率是最重要的输运性质之一，可以更好地约束核幔边界（CMB）的温度分布和动力学。铁掺入ppv会影响其导电性，这一点从未被实验研究过。本文采用最新发展的脉冲光加热热反射技术，结合连续波加热激光器，测定了含铁量为3mol %和10mol %的ppv在高压条件下（压力分别为149gpa和177gpa，温度为1560k）的晶格导热系数。我们发现，在ppv中掺入铁会适度降低其晶格导热系数，因为它增加了铁的含量。以ppv为主的软锰矿的体电导率比下地幔中由桥锰矿和铁方长石组成的软锰矿的体电导率高1.5倍，这与地球最下层地幔中ppv比桥锰矿更好导热的传统观点一致。
The thermal conductivity of post-perovskite (ppv), the highest-pressure polymorph of MgSiO3in the Earth's mantle, is one of the most important transport properties for providing better constraints on the temperature profile and dynamics at the core-mantle boundary (CMB). Incorporation of Fe into ppv can affect its conductivity, which has never been experimentally investigated. Here we determined the lattice thermal conductivities of ppv containing 3 mol% and 10 mol% of Fe at highP-Tconditions – of pressures up to 149 GPa and 177 GPa, respectively, and temperatures up to 1560 K – by means of the recently developed pulsed light heating thermoreflectance technique combining continuous wave heating lasers. We found that the incorporation of Fe into ppv moderately reduces its lattice thermal conductivity as it increases the Fe content. The bulk conductivity of ppv dominant pyrolite is estimated as 1.5 times higher than that of pyrolite consisting of bridgmanite and ferropericlase in the lower mantle, which agrees with the traditional view that ppv acts as a better heat conductor than bridgmanite in the Earth's lowermost mantle.