CSEDI: Alkaline-Earth Carbonate Melts at Deep Earth Conditions

CSEDI：碱土碳酸盐在地球深处熔化

• 批准号: 1763189
• 负责人: Jie Li
• 金额: $ 68万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-15 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1763189&HistoricalAwards=false
• 关键词: CSEDI; Alkaline; Earth; Carbonate; Melts

Carbonates are common rock-forming minerals that contain significant carbon in their crystal structures, and thus represent a dominant reservoir for carbon in the Earth System. Despite their primary role in the long-term carbon cycle, we currently have a very limited understanding of their melting behavior at the relevant conditions deep inside the Earth. The carbon hosted in carbonate-bearing rocks is carried into the Earth by subducting oceanic plates, where it is either returned to the surface through volcanism or dragged further down into the deep mantle, depending on the depth of carbonate melting. The melting properties of carbonates thus directly control the long-term component of Earth's carbon cycle. This project is focused on better understanding the details of carbonate melting at extreme pressures and temperatures by combining diverse research techniques using experiments, simulations, and statistical modeling. In addition to improving our fundamental understanding of the deep carbon cycle, this project supports developing both technical and leadership expertise; the project is being led by an early career research scientist who will join the co-investigators in the training of two graduate students in a variety of cutting edge research techniques that are also broadly applicable to future material properties research.The thermodynamic melting properties of carbonates directly control the long-term component of Earth's carbon cycle, and yet this key area has remained poorly understood as a result of practical challenges for carbonate melting experiments. These difficulties include decomposition prior to melting at pressures below ~3 GPa, as well as extreme sensitivities of the melting behavior to pressure, temperature, and composition (including water content), which severely complicate analysis of such experiments. The goal of this proposal is to combine multiple experimental and theoretical methods to characterize the thermodynamics of solid and molten alkaline earth carbonates, in the (Ca,Mg,Sr,Ba)CO3 system, which encompasses the dominant Mg-Ca bearing components most relevant to the deep Earth. The team's experimental objectives are to: (1) carry out conductivity-based in situ melt detection experiments up to 25 GPa for each endmember, (2) conduct liquid one-bar density and sound speed measurements to determine how each component affects melt density and compressibility, and (3) perform laser-heated diamond anvil cell measurements to constrain the high pressure-temperature (PT) equations of state of the solidus phases. These are combined with theoretical objectives to: (1) simulate the alkaline earth carbonate system using empirical molecular dynamics to predict high PT properties for both melt and mineral phases and (2) employ Bayesian statistical analysis to obtain a global self-consistent thermodynamic model of the (Ca,Mg,Sr,Ba)CO3 system. The final thermodynamic picture provided by this work represents a major stepping-stone on the path to incorporating carbonate melting into a variety of widely-used thermodynamic databases that underpin our understanding of geologic processes at extreme planetary conditions. Together the five techniques employed in this work, which rely on the cooperation and distinct expertise of the three principal investigators, will provide a comprehensive thermodynamic view of carbonate melting at deep mantle conditions.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.

碳酸盐是常见的造岩矿物，在其晶体结构中含有大量的碳，因此代表了地球系统中碳的主要储层。尽管它们在长期碳循环中发挥着主要作用，但我们目前对它们在地球深处相关条件下的融化行为的了解非常有限。含碳酸盐岩中的碳通过俯冲的海洋板块被带入地球，在那里，它要么通过火山作用返回到地表，要么被进一步拉入地幔深处，这取决于碳酸盐熔融的深度。因此，碳酸盐的熔融特性直接控制着地球碳循环的长期组成部分。该项目的重点是通过结合使用实验，模拟和统计建模的各种研究技术，更好地了解极端压力和温度下碳酸盐熔融的细节。除了提高我们对深层碳循环的基本理解外，该项目还支持发展技术和领导能力。该项目由一位早期职业研究科学家领导，他将加入联合国，研究人员在培训两名研究生在各种尖端的研究技术，也广泛适用于未来的材料性能的研究。直接控制地球碳循环的长期组成部分，但由于碳酸盐融化实验的实际挑战，这一关键领域仍然知之甚少。这些困难包括在低于约3GPa的压力下熔化之前的分解，以及熔化行为对压力、温度和组成（包括水含量）的极端敏感性，这使得此类实验的分析严重复杂化。该提案的目标是联合收割机多种实验和理论方法来表征固体和熔融碱土碳酸盐的热力学，在（Ca，Mg，Sr，Ba）CO 3系统，其中包括占主导地位的Mg-Ca轴承组件最相关的深地球。该团队的实验目标是：（1）对每个端元进行高达25 GPa的基于电导率的原位熔体检测实验，（2）进行液体单杆密度和声速测量以确定每个组分如何影响熔体密度和可压缩性，以及（3）进行激光加热金刚石砧座单元测量以约束固相线相的高压-温度（PT）状态方程。这些都结合了理论目标：（1）模拟碱土金属碳酸盐系统使用经验分子动力学预测高PT性能的熔体和矿物相和（2）采用贝叶斯统计分析，以获得一个全球性的自洽的（Ca，Mg，Sr，Ba）CO 3系统的热力学模型。这项工作提供的最终热力学图像代表了将碳酸盐熔融纳入各种广泛使用的热力学数据库的道路上的主要垫脚石，这些数据库支持我们对极端行星条件下地质过程的理解。这项工作中采用的五种技术，依赖于三位主要研究人员的合作和独特的专业知识，将提供一个全面的热力学观点，碳酸盐熔融在深地幔conditions.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Metallic iron limits silicate hydration in Earth’s transition zone

• DOI: 10.1073/pnas.1908716116
• 发表时间: 2019-10
• 期刊: Proceedings of the National Academy of Sciences
• 作者: F. Zhu;Jie Li;Jiachao Liu;Junjie Dong;Zhenxian Liu

Liquidus determination of the Fe-S and (Fe, Ni)-S systems at 14 and 24 GPa: Implications for the Mercurian core

14 和 24 GPa 下 Fe-S 和 (Fe, Ni)-S 系统的液相线测定：对 Mercurian 核心的影响

• DOI: 10.1016/j.epsl.2022.117865
• 发表时间: 2022
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Pease, Allison;Li, Jie
• 通讯作者: Li, Jie

Castable solid pressure media for multianvil devices

• DOI: 10.1063/1.5129534
• 发表时间: 2020-01
• 期刊: Matter and Radiation at Extremes
• 影响因子: 5.1
• 作者: D. Walker;Jie Li

The density of Li2CO3-Na2CO3-K2CO3-Rb2CO3-Cs2CO3-CaCO3-SrCO3-BaCO3 liquids: New measurements, ideal mixing, and systematic trends with composition

Li2CO3-Na2CO3-K2CO3-Rb2CO3-Cs2CO3-CaCO3-SrCO3-BaCO3 液体的密度：新测量、理想混合和成分的系统趋势

• DOI: 10.1016/j.gca.2018.12.031
• 发表时间: 2019
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Hurt, Sean M.;Lange, Rebecca A.
• 通讯作者: Lange, Rebecca A.

Origin and consequences of non-stoichiometry in iron carbide Fe7C3

碳化铁 Fe7C3 中非化学计量的起源和后果

• DOI: 10.2138/am-2019-6672
• 发表时间: 2019
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Zhu, Feng;Li, Jie;Walker, David;Liu, Jiachao;Lai, Xiaojing;Zhang, Dongzhou
• 通讯作者: Zhang, Dongzhou