TY - JOUR
T1 - Fluorine and chlorine fractionation during magma ocean crystallization
T2 - Constraints on the origin of the non-chondritic F/Cl ratio of the Earth
AU - Kuwahara, Hideharu
AU - Kagoshima, Takanori
AU - Nakada, Ryoichi
AU - Ogawa, Nobuhiro
AU - Yamaguchi, Asuka
AU - Sano, Yuji
AU - Irifune, Tetsuo
N1 - Funding Information:
We greatly appreciate Dr. Kenji Shimizu at the Kochi Institute of Core Sample Research, Japan Agency for Marine-Earth Science and Technology for providing the standard glasses for the NanoSIMS analyses and his helpful comments on the preparation of these samples. We also greatly appreciate Dr. Klaus Peter Jochum at the Max Plank Institute for Chemistry for providing the natural glass standards. We are grateful to Dr. Bruce Fegley at Washington University, St. Louis for his comments on the 50% condensation temperature of halogens. We thank the two anonymous reviewers for their reviews and constructive comments on the manuscript. We are also grateful to Dr. Tamsin A. Mather for editorial handling of the manuscript and helpful comments. We thank Guy Evans, PhD, from Edanz Group ( www.edanzediting.com/ac ) for editing a draft of this manuscript. The research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI to H. Kuwahara (Grant Number 15J06330 , 18J00966 , and 18K13635 ). This research was supported by the Cooperative Program of the Atmosphere and Ocean Research Institute, The University of Tokyo .
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/8/15
Y1 - 2019/8/15
N2 - Previous studies have reported that the relative abundances of volatile elements in the silicate Earth are non-chondritic. The abundance and distribution of volatile elements in terrestrial planets would have been predominantly controlled by planetary formation processes, including core-mantle separation, magma ocean crystallization, and volatility-dependent high-temperature fractionation. Thus, the current abundance patterns of volatile elements in the silicate fraction of terrestrial planets are the key to understanding the accretional history of terrestrial volatiles and the chemical differentiation of terrestrial planets. Although the origin of the non-chondritic ratios of volatile elements in terrestrial planets has been previously studied, it is still a matter of debate. In this study, we focused on the super-chondritic F/Cl ratio of the bulk silicate Earth and experimentally investigated the silicate mineral-melt partitioning of fluorine and chlorine at pressures from 18 GPa to 25 GPa. Our experimental results show that fluorine is moderately compatible with mantle minerals, whereas chlorine is highly incompatible. These results support the formation of a solid mantle with high F/Cl ratios, and a residual magma ocean and steam atmosphere with low F/Cl ratios during magma ocean crystallization. Thus, the F/Cl ratio in the residual solid parts of terrestrial planets would have become relatively enriched following escape of volatile elements from the planetary surface into outer space. This model is consistent with the collisional erosion hypothesis of primordial crusts and atmospheres, and current observations on the abundance and distribution of terrestrial fluorine and chlorine.
AB - Previous studies have reported that the relative abundances of volatile elements in the silicate Earth are non-chondritic. The abundance and distribution of volatile elements in terrestrial planets would have been predominantly controlled by planetary formation processes, including core-mantle separation, magma ocean crystallization, and volatility-dependent high-temperature fractionation. Thus, the current abundance patterns of volatile elements in the silicate fraction of terrestrial planets are the key to understanding the accretional history of terrestrial volatiles and the chemical differentiation of terrestrial planets. Although the origin of the non-chondritic ratios of volatile elements in terrestrial planets has been previously studied, it is still a matter of debate. In this study, we focused on the super-chondritic F/Cl ratio of the bulk silicate Earth and experimentally investigated the silicate mineral-melt partitioning of fluorine and chlorine at pressures from 18 GPa to 25 GPa. Our experimental results show that fluorine is moderately compatible with mantle minerals, whereas chlorine is highly incompatible. These results support the formation of a solid mantle with high F/Cl ratios, and a residual magma ocean and steam atmosphere with low F/Cl ratios during magma ocean crystallization. Thus, the F/Cl ratio in the residual solid parts of terrestrial planets would have become relatively enriched following escape of volatile elements from the planetary surface into outer space. This model is consistent with the collisional erosion hypothesis of primordial crusts and atmospheres, and current observations on the abundance and distribution of terrestrial fluorine and chlorine.
KW - chlorine
KW - fluorine
KW - magma ocean
KW - partitioning
KW - terrestrial planets
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U2 - 10.1016/j.epsl.2019.05.041
DO - 10.1016/j.epsl.2019.05.041
M3 - Article
AN - SCOPUS:85067197414
SN - 0012-821X
VL - 520
SP - 241
EP - 249
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
ER -