Thermal Conductivity Anomaly in (Fe0.78Mg0.22)CO3 Siderite Across Spin Transition of Iron
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2019-02-01 |
| Journal | Journal of Geophysical Research Solid Earth |
| Authors | KengâHsien Chao, WenâPin Hsieh |
| Institutions | Institute of Earth Sciences, Academia Sinica, National Taiwan University |
| Citations | 17 |
Abstract
Section titled âAbstractâAbstract Siderite was proposed to be an important mantle carbonâhosting mineral in Earthâs deep carbon cycle. It undergoes a pressureâinduced spin transition of iron around 40-55 GPa, through which many physical properties change drastically. Thermal conductivity of mantle minerals is key to control temperature profiles and thermal evolution in the mantle and subducting slabs. However, the lattice thermal conductivity of ironâbearing carbonates under relevant mantle conditions has never been investigated. Here we combined highâpressure diamondâanvil cell, Raman spectroscopy, and ultrafast optical pumpâprobe method to measure the lattice thermal conductivity of siderite to 67 GPa at room temperature. We found that during the spin transition the thermal conductivity varies significantly with the extent of lowâspin state, which is largely different from that of the lowerâmantle ferropericlase. Our results further suggest that when the siderite is transported to depths of 1,400-1,800 km, such thermal conductivity anomaly within a narrow pressure range may induce anomalies in local thermochemical profiles and alter the distribution fields of subducting minerals, which in turn would influence the fate of carbonates in global carbon cycle.