TY - JOUR
T1 - A Refined Approach to Model Anisotropy in the Lowermost Mantle
AU - Chandler, B. C.
AU - Yuan, K.
AU - Li, Mingming
AU - Cottaar, S.
AU - Romanowicz, B.
AU - Tomé, C. N.
AU - Wenk, H. R.
N1 - Funding Information:
Acknowledgments HRW is grateful to the organizers of ICOTOM18 for arranging this fascinating overview of texture research, from history to state-of-the-art. We acknowledge discussions with Pamela Kaercher, Lowell Miyagi and D. Dobson as well as support from NSF (EAR 1343908, 1417229, CSEDI-106751), DOE (DE-FG02-05ER15637) and CDAC.
Publisher Copyright:
© 2018 Institute of Physics Publishing. All rights reserved.
PY - 2018/6/18
Y1 - 2018/6/18
N2 - Seismic anisotropy in the lowermost mantle has been attributed to texture development during mantle convection. This study models texture evolution in a subducting slab impinging on the core-mantle boundary. Using a 3-dimensional geodynamic model with tracers recording the deformation history, a visco-plastic self-consistent (VPSC) model for polycrystal deformation, and relying on experimentally determined slip systems, aggregate grains with volume fractions of 60% orthorhombic silicate perovskite (MgSiO3), 20% cubic calcium perovskite (CaSiO3), and 20% cubic ferropericlase ((Mg,Fe)O) were deformed plastically and developed crystal preferred orientation. Forward and reverse perovskite (Pv)-postperovskite (PPv) phase transitions were included by allowing for likely orientation variant selections. Grain orientations, P (compression) and S (shear) wave velocity pole figures were calculated for each phase as well as the aggregate. The results show that dominant (001) slip on PPv can produce strong texture and shear wave anisotropy of 0.01-3.07% with VSH >VSV which agrees with seismological observations in selected areas of the D" layer.
AB - Seismic anisotropy in the lowermost mantle has been attributed to texture development during mantle convection. This study models texture evolution in a subducting slab impinging on the core-mantle boundary. Using a 3-dimensional geodynamic model with tracers recording the deformation history, a visco-plastic self-consistent (VPSC) model for polycrystal deformation, and relying on experimentally determined slip systems, aggregate grains with volume fractions of 60% orthorhombic silicate perovskite (MgSiO3), 20% cubic calcium perovskite (CaSiO3), and 20% cubic ferropericlase ((Mg,Fe)O) were deformed plastically and developed crystal preferred orientation. Forward and reverse perovskite (Pv)-postperovskite (PPv) phase transitions were included by allowing for likely orientation variant selections. Grain orientations, P (compression) and S (shear) wave velocity pole figures were calculated for each phase as well as the aggregate. The results show that dominant (001) slip on PPv can produce strong texture and shear wave anisotropy of 0.01-3.07% with VSH >VSV which agrees with seismological observations in selected areas of the D" layer.
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U2 - 10.1088/1757-899X/375/1/012002
DO - 10.1088/1757-899X/375/1/012002
M3 - Conference article
AN - SCOPUS:85049407740
SN - 1757-8981
VL - 375
JO - IOP Conference Series: Materials Science and Engineering
JF - IOP Conference Series: Materials Science and Engineering
IS - 1
M1 - 012002
T2 - 18th International Conference on Textures of Materials, ICOTOM 2017
Y2 - 6 November 2017 through 10 November 2017
ER -