Understanding the solid solution effects of iron on the thermoelasticity and thermal conductivity of the lower mantle minerals

2016 Fiscal Year Final Research Report

• Project/Area Number: 26287137
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Ehime University
• Principal Investigator: Tsuchiya Taku 愛媛大学, 地球深部ダイナミクス研究センター, 教授 (70403863)
• Co-Investigator(Kenkyū-buntansha): 土屋 旬 愛媛大学, 地球深部ダイナミクス研究センター, 准教授 (00527608) ; 出倉 春彦 愛媛大学, 地球深部ダイナミクス研究センター, 助教 (90700146)
• Co-Investigator(Renkei-kenkyūsha): DEKURA Haruhiko 愛媛大学, 地球深部ダイナミクス研究センター, 講師 (90700146)
• Research Collaborator: HASE Atsushi ; ICHIKAWA Hiroki ; WANG Xianlong ; XIONG Zhihua
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 第一原理計算 / 熱弾性特性 / 熱伝導特性 / 鉄固溶効果 / 下部マントル / 含水鉱物

Outline of Final Research Achievements

Original approaches to compute thermoelasticity and thermal conductivity were developed based on the harmonic and anharmonic lattice dynamics theories combined with the internally-consistent DFT+U method, high-pressure and high-temperature elasticities and lattice thermal conductivities of iron and aluminum bearing bridgmanite (Br), ferropericlase (Fp), and post-perovskite (PPv) were calculated. It was found that the pyrolitic composition can reproduce seismological properties observed in the lower mantle and that Fp has thermal conductivity several times larger than the others. The techniques were also applied to iron hydroxide, and then a new high-pressure phase with the pyrite structure was successfully discovered. These results propose new pictures of the mantle dynamics that Earth's mantle is now in the whole convection state, where the upper and lower mantles convect integrally, and the surface water can be transported down to the bottom of the mantle located at 2890 km depth.

Free Research Field

鉱物物性理論