Crystal Buoyancy in the Deep Magma Ocean

GSTDTAP

项目编号	1853388
	Crystal Buoyancy in the Deep Magma Ocean
	Lars Stixrude (Principal Investigator)
主持机构	University of California-Los Angeles
项目开始年	2019
	2019-04-01
项目结束日期	2022-03-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	458000(USD)
国家	美国
语种	英语
英文摘要	Present-day Earth is the product of an evolutionary process which began with a largely or completely molten planet. This project aims to constrain the iron contents of solid and liquid phases in the early magma ocean. Whether solids rise or sink in a magma depends on their density contrast with the liquid, which is a function of their relative iron contents. The distribution of iron between phases is called partitioning. Quantifying iron partitioning in the early magma ocean is critical to model Earth's mantle evolution toward its present-day structure and composition. Here, the researcher uses computational physics to model at the atomic level the chemistry of iron in the magma. The simulation - called "ab initio" because it relies on quantum-mechanics first principles - accounts for the extreme pressures prevailing in the deep magma ocean. The team's state-of-the-art code includes developments which allow calculating the affinity of iron with solid and liquid phases, thus whether minerals rise or sink. This project promotes the training of a graduate student in computational Mineral Physics. It impacts the adjacent fields of Experimental Petrology and Geodynamics, with strong implications for the interpretation of modern geochemical and seismological observations. It also has broad impacts in Materials Science. Previous work has shown that whether crystals rise or sink in a magma ocean depends critically on the partitioning of iron between liquid and crystalline phases. Yet, the sign of the liquid-crystal density contrast and the vector of geochemical evolution is unknown at the conditions of the deep magma ocean. Here, the PI and his team calculates ab initio the partitioning of iron among coexisting phases throughout the pressure regime of the lower mantle. The project represents a major expansion for the application of density functional theory to the magma ocean. It encompasses studies of end-member compositions and the chemical interaction between liquids and crystals. The team build on their accomplishments in ab initio simulation of Earth's iron-bearing systems - including strong correlation and magnetic entropy - by broadening the scope to account for free energies and element partitioning. Using first principles molecular dynamics coupled with adiabatic switching, they will predict iron partitioning between: 1) liquid and crystalline (Mg,Fe)O , 2) liquid and crystalline (Mg,Fe)SiO3 and 3) a liquid approximating bulk silicate Earth composition and (Mg,Fe)O ferropericlase and (Mg,Fe)SiO3 bridgmanite. 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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/213334
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Lars Stixrude .Crystal Buoyancy in the Deep Magma Ocean.2019.