题目：Davemaoite does exist in the lower mantle

下地幔高压高温极端环境下存在CaSiO₃毛钙硅石

报告时间：2024年9月25日（周三）上午10:00

报告地点：超硬实验综合楼5楼B520报告厅

报告人：Tomoo Katsura (桂 智男) 教授，德国拜罗伊特大学

个人简介：Tomoo Katsura博士，德国拜罗伊特大学巴伐利亚地质研究所（BGI）教授,国际高压界著名专家，1986年日本京都大学本科毕业，1991年在日本冈山大学获得博士学位。1993–2010年历任日本冈山大学行星材料研究所助理教授、副教授、教授；2010年4月–至今，德国拜罗伊特大学BGI研究所教授、所长（2012-2015）。主要研究领域包括大腔体高温高压实验技术、高压矿物物理和地球内部物理。目前为美国矿物学会（MSA）、美国地球物理学会（AGU）会士，Reviews of Geophysics副主编,已发表学术论文200多篇,其中包含8篇Nature和Science文章。

报告摘要：Davemaoite, CaSiO₃ perovskite, is believed to be the third most abundant mineral in Earth's lower mantle. Its stability is essential for understanding the chemical evolution and dynamics of the Earth's mantle because it holds trace elements, unlike other lower mantle minerals, bridgmanite and ferropericlase. However, the presence of davemaoite in the lower mantle remains controversial. A recent study by Ko et al.(Nature,611,88,2022) using laser-heated diamond anvil cells (DAC) reported that the solubility of CaSiO₃ in bridgmanite increases significantly above 2300 K and 40 GPa. This led to the conclusion that davemaoite is absent in regions deeper than 1800 km in the mantle because all the CaSiO3 in pyrolite is contained in bridgmanite. To verify this conclusion, we performed multi-anvil experiments at pressures ranging from 27 to 50 GPa and temperatures between 2300 and 2700 K with five different compositions using the ultrahigh-pressure-temperature multi-anvil technology and examined the run products using transmission electron microscopy. Our results show that Ca solubility in bridgmanite cannot eliminate davemaoite under typical mantle conditions, including representative pressures, temperatures, and chemical compositions. Based on these results, we conclude that davemaoite does exist in Earth's lower mantle, contrary to the suggestion of Ko et al.(Nature,611,88,2022).