Fe-Mn interdiffusion in aluminosilicate garnets  

作　　者：Yanjun Yin Baohua Zhang Xinzhuan Guo 

机构地区：[1]Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,Guizhou,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory of Big Data in Geosciences and Deep Earth Resources of Zhejiang Province,School of Earth Sciences,Zhejiang University,Hangzhou 310058,China

出　　处：《Geoscience Frontiers》2024年第1期118-125,共8页地学前缘（英文版）

基　　金：supported by the National Natural Science Foundation of China (41973056,41773056);Key Research Program of Frontier Sciences of CAS (ZDBS-LY-DQC015)to B.Zhang;the Fundamental Research Funds for the Central Universities (K20210168);Data presented as part of this study are available from Zenodo (https://doi.org/10.5281/zenodo.7080353).

摘　　要：Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes,but very few studies have been performed for Fe-Mn interdiffusion.In this study,Fe-Mn interdiffusion rates in natural single crystals of Mn-bearing garnet with 750 ppm H2O are determined at 6 GPa and 1273-1573 K in a Kawai-type multi-anvil apparatus.Diffusion profiles were acquired by electron microprobe and fitted using Boltzmann-Matano equation.The experimental results show that the Fe-Mn interdiffusion coefficient(DFe-Mn)slightly decreases with increasing XFe.The experimentally determined DFe-Mn in Mn-bearing garnet can be fitted by the Arrhenius equation:DFe-Mn(m2/s)=D0XFenexp(-E*/RT),where E*=(1-XFe)E*Mn+XFeE*Fe,D0=8.06-6.04+9.87×10-9 m2/s,E*Mn=248±27 KJ/mol,E*Fe=226±59 KJ/mol,n=-1.36±0.51.The comparing the present results with previous experimental data suggest that water can greatly enhance the DFe-Mn in garnet.Our results indicate that the time required for homogenization of the compositional zoning of a garnet is much shorter than previously thought.

关 键 词：Fe-Mn interdiffusion Diffusion coefficient GARNET High pressure experiment Water 

分 类 号：P597.3[天文地球—地球化学] P588.3[天文地球—地质学]