A model for C-O-H fluid in the Earth's mantle

被引:155
|
作者
Zhang, Chi [2 ]
Duan, Zhenhao [1 ]
机构
[1] Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earths Deep Interior, Beijing 100029, Peoples R China
[2] China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China
基金
美国国家科学基金会;
关键词
MOLECULAR-DYNAMICS SIMULATION; OXYGEN FUGACITY; PVT PROPERTIES; HIGH-PRESSURE; EXCEL SPREADSHEET; HIGH-TEMPERATURES; ROCK INTERACTIONS; H2O-CO2; MIXTURES; GENERAL EQUATION; DIAMOND GENESIS;
D O I
10.1016/j.gca.2009.01.021
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
A model is presented for predicting the composition (H2O, CO2, CH4, H-2, CO, O-2 and C2H6) in the C-O-H fluid system under high temperatures and pressures found in the Earth's mantle. The model is based on a molecular dynamic equation of state, statistical mechanics calculations and non-stoichiometric global free-energy minimization. Although the model is not fitted to experimental data on C-O-H speciation, it does accurately reproduce these datasets and should extrapolate at least to the depths of similar to 80-220 km. The model results suggest that (1) in the upper cratonic mantle, H2O is the dominant fluid species in the C-O-H fluid system; (2) the abundance of CO2 increases with decreasing depth, the trend of CH4 is just the opposite; (3) the boundary between lithosphere and asthenosphere generally divides fluid systems into H2O-CH4+ minor species and H2O-CO2+ minor species, respectively; (4) it is entirely possible to generate methane and ethane and possibly other hydrocarbons under mantle conditions, confirming previously experimental results. (c) 2009 Published by Elsevier Ltd.
引用
收藏
页码:2089 / 2102
页数:14
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