TY - JOUR
T1 - The influence of δ-(Al,Fe)OOH on seismic heterogeneities in Earth’s lower mantle
AU - Ohira, Itaru
AU - Jackson, Jennifer M.
AU - Sturhahn, Wolfgang
AU - Finkelstein, Gregory J.
AU - Kawazoe, Takaaki
AU - Toellner, Thomas S.
AU - Suzuki, Akio
AU - Ohtani, Eiji
N1 - Funding Information:
We warmly thank Y. Ito for his help with polishing and performing the EPMA-analysis of the crystals used in this work, and Natalia V. Solomatova, Rachel A. Morrison, and Vasilije Dobrosavljevic for help during the experiments. This work was supported by JSPS KAKENHI Grant Numbers JP16J04690, JP20K22369 to I.O., JP15H05828, JP19H01985, JP19K21890 to A.S., JP15H05748, JP20H00187 to E.O., the International Research and Training Group “Deep Earth Volatile Cycles” funded by the German Science Foundation (Grant Number: GRK 2156/1), the JSPS Japanese-German Graduate Externship, the International Joint Graduate Program in Earth and Environmental Science, Tohoku University (GP-EES), and by Grants awarded to J.M.J by the National Science Foundation (NSF-CSEDI-EAR-1600956 and 2009935) and the W.M. Keck Institute for Space Studies. The NRIXS experiments were conducted at 3-ID-B, Advanced Photon Source, the United States, which is partially supported by COMPRES. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12
Y1 - 2021/12
N2 - The high-pressure phases of oxyhydroxides (δ-AlOOH, ε-FeOOH, and their solid solution), candidate components of subducted slabs, have wide stability fields, thus potentially influencing volatile circulation and dynamics in the Earth’s lower mantle. Here, we report the elastic wave velocities of δ-(Al,Fe)OOH (Fe/(Al + Fe) = 0.13, δ-Fe13) to 79 GPa, determined by nuclear resonant inelastic X-ray scattering. At pressures below 20 GPa, a softening of the phonon spectra is observed. With increasing pressure up to the Fe3+ spin crossover (~ 45 GPa), the Debye sound velocity (vD) increases. At higher pressures, the low spin δ-Fe13 is characterized by a pressure-invariant vD. Using the equation of state for the same sample, the shear-, compressional-, and bulk-velocities (vS, vP, and vΦ) are calculated and extrapolated to deep mantle conditions. The obtained velocity data show that δ-(Al,Fe)OOH may cause low-vΦ and low-vP anomalies in the shallow lower mantle. At deeper depths, we find that this hydrous phase reproduces the anti-correlation between vS and vΦ reported for the large low seismic velocity provinces, thus serving as a potential seismic signature of hydrous circulation in the lower mantle.
AB - The high-pressure phases of oxyhydroxides (δ-AlOOH, ε-FeOOH, and their solid solution), candidate components of subducted slabs, have wide stability fields, thus potentially influencing volatile circulation and dynamics in the Earth’s lower mantle. Here, we report the elastic wave velocities of δ-(Al,Fe)OOH (Fe/(Al + Fe) = 0.13, δ-Fe13) to 79 GPa, determined by nuclear resonant inelastic X-ray scattering. At pressures below 20 GPa, a softening of the phonon spectra is observed. With increasing pressure up to the Fe3+ spin crossover (~ 45 GPa), the Debye sound velocity (vD) increases. At higher pressures, the low spin δ-Fe13 is characterized by a pressure-invariant vD. Using the equation of state for the same sample, the shear-, compressional-, and bulk-velocities (vS, vP, and vΦ) are calculated and extrapolated to deep mantle conditions. The obtained velocity data show that δ-(Al,Fe)OOH may cause low-vΦ and low-vP anomalies in the shallow lower mantle. At deeper depths, we find that this hydrous phase reproduces the anti-correlation between vS and vΦ reported for the large low seismic velocity provinces, thus serving as a potential seismic signature of hydrous circulation in the lower mantle.
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U2 - 10.1038/s41598-021-91180-9
DO - 10.1038/s41598-021-91180-9
M3 - Article
C2 - 34103572
AN - SCOPUS:85107822903
SN - 2045-2322
VL - 11
JO - Scientific Reports
JF - Scientific Reports
IS - 1
M1 - 12036
ER -