TY - JOUR
T1 - Water Concentration in Single-Crystal (Al,Fe)-Bearing Bridgmanite Grown From the Hydrous Melt
T2 - Implications for Dehydration Melting at the Topmost Lower Mantle
AU - Fu, Suyu
AU - Yang, Jing
AU - Karato, Shun ichiro
AU - Vasiliev, Alexander
AU - Presniakov, Mikhail Yu
AU - Gavrilliuk, Alexander G.
AU - Ivanova, Anna G.
AU - Hauri, Erik H.
AU - Okuchi, Takuo
AU - Purevjav, Narangoo
AU - Lin, Jung Fu
N1 - Funding Information:
The authors thank Z. Jiang for his assistance with FTIR measurements at Yale University and a discussion on TEM results. The authors thank C. McCammon for helping with M?ssbauer spectroscopy data collection and data analysis on the bridgmanite crystals. We acknowledge V. Prakapenka for the assistance with X-ray diffraction experiments at 13ID-D, GSECARS. GSECARS operations are supported by the National Science Foundation-Earth Sciences (EAR-1128799) and the U.S. Department of Energy, Geosciences (DE-FG02-94ER14466). J. F. L. acknowledges support from National Science Foundation Geophysics Program (EAR-1446946 & EAR-1916941) and Deep Carbon Observatory of the Sloan Foundation. S. K. acknowledges support from EAR-1082622. A. G. G. acknowledges support of RScF 16-12-10464 grant and Center for Collective Use ?Accelerator Center for Neutron Research of the Structure of Substance and Nuclear Medicine? of the INR RAS. TEM analyses were supported by the Ministry of Science and Higher Education within the State assignment FSRC ?Crystallography and Photonics? RAS. Experimental data for EPMA are listed in Table?S1. Raw unpolarized and polarized FTIR data are available in the supporting information. All the data to produce all the figures in this paper are available on Zenodo (http://doi.org/10.5281/zenodo.3364107). More detailed information of experimental results can be found in the supporting information.
Funding Information:
The authors thank Z. Jiang for his assistance with FTIR measurements at Yale University and a discussion on TEM results. The authors thank C. McCammon for helping with Mössbauer spectroscopy data collection and data analysis on the bridgmanite crystals. We acknowledge V. Prakapenka for the assistance with X‐ray diffraction experiments at 13ID‐D, GSECARS. GSECARS operations are supported by the National Science Foundation‐Earth Sciences (EAR‐1128799) and the U.S. Department of Energy, Geosciences (DE‐FG02‐94ER14466). J. F. L. acknowledges support from National Science Foundation Geophysics Program (EAR‐1446946 & EAR‐1916941) and Deep Carbon Observatory of the Sloan Foundation. S. K. acknowledges support from EAR‐1082622. A. G. G. acknowledges support of RScF 16‐12‐10464 grant and Center for Collective Use “Accelerator Center for Neutron Research of the Structure of Substance and Nuclear Medicine” of the INR RAS. TEM analyses were supported by the Ministry of Science and Higher Education within the State assignment FSRC «Crystallography and Photonics» RAS. Experimental data for EPMA are listed in Table S1 . Raw unpolarized and polarized FTIR data are available in the supporting information . All the data to produce all the figures in this paper are available on Zenodo ( http://doi.org/10.5281/zenodo.3364107 ). More detailed information of experimental results can be found in the supporting information .
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/9/1
Y1 - 2019/9/1
N2 - High-quality single-crystals of (Al,Fe)-bearing bridgmanite, Mg0.88 Fe3+ 0.065Fe2+ 0.035Al0.14Si0.90O3, of hundreds of micrometer size were synthesized at 24 GPa and 1800 °C in a Kawai-type apparatus from the starting hydrous melt containing ~6.7 wt% water. Analyses of synthesized bridgmanite using petrographic microscopy, scanning electron microscopy, and transmission electron microscopy show that the crystals are chemically homogeneous and inclusion free in micrometer- to nanometer-spatial resolutions. Nanosecondary ion mass spectrometry (NanoSIMS) analyses on selected platelets show ~1,020(±70) ppm wt water (hydrogen). The high water concentration in the structure of bridgmanite was further confirmed using polarized and unpolarized Fourier-transform infrared spectroscopy (FTIR) analyses with two pronounced OH-stretching bands at ~3,230 and ~3,460 cm−1. Our results indicate that lower-mantle bridgmanite can accommodate relatively high amount of water. Therefore, dehydration melting at the topmost lower mantle by downward flow of transition zone materials would require water content exceeding ~0.1 wt%.
AB - High-quality single-crystals of (Al,Fe)-bearing bridgmanite, Mg0.88 Fe3+ 0.065Fe2+ 0.035Al0.14Si0.90O3, of hundreds of micrometer size were synthesized at 24 GPa and 1800 °C in a Kawai-type apparatus from the starting hydrous melt containing ~6.7 wt% water. Analyses of synthesized bridgmanite using petrographic microscopy, scanning electron microscopy, and transmission electron microscopy show that the crystals are chemically homogeneous and inclusion free in micrometer- to nanometer-spatial resolutions. Nanosecondary ion mass spectrometry (NanoSIMS) analyses on selected platelets show ~1,020(±70) ppm wt water (hydrogen). The high water concentration in the structure of bridgmanite was further confirmed using polarized and unpolarized Fourier-transform infrared spectroscopy (FTIR) analyses with two pronounced OH-stretching bands at ~3,230 and ~3,460 cm−1. Our results indicate that lower-mantle bridgmanite can accommodate relatively high amount of water. Therefore, dehydration melting at the topmost lower mantle by downward flow of transition zone materials would require water content exceeding ~0.1 wt%.
KW - dehydration melting
KW - lower mantle
KW - single-crystal bridgmanite
KW - transition zone
KW - water solubility
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U2 - 10.1029/2019GL084630
DO - 10.1029/2019GL084630
M3 - Article
AN - SCOPUS:85071763869
SN - 0094-8276
VL - 46
SP - 10346
EP - 10357
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 17-18
ER -