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Core-Mantle Boundary Dynamic Topography: Influence of Postperovskite Viscosity
Deschamps, Frederic1; Li, Yang2
2019-08-01
Source PublicationJOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
ISSN2169-9313
Volume124Issue:8Pages:9247-9264
AbstractCore-mantle boundary (CMB) topography may provide useful hints on the deep mantle thermochemical structure, as clusters of thermal plumes and piles of chemically differentiated material, which are usually proposed as end-member explanations for the large low shear-wave velocity regions observed in the deep mantle, have different actions on this topography. CMB topography is further sensitive to several parameters, including mantle viscosity and its variations with thermal and compositional changes. Here we assess the influence of the postperovskite (pPv) phase viscosity on deep mantle dynamics and on CMB topography. We perform numerical simulations of thermal and thermochemical convection in spherical geometry, varying the ratio between pPv and bridgmanite viscosities, Delta eta(pPv), between 1 (regular pPv) and 10(-3) (weak pPv). Thermochemical structures are dominated by smaller-scale wavelengths (spherical harmonic degrees 3 to 6) and are more stable in weak than in regular pPv models. The amplitude of CMB topography is reduced by about a factor of 2 as Delta eta(pPv) changes from 1 to 10(-3), mostly due to a sharp drop in the depressions induced by downwellings reaching the CMB. By contrast, the topographies induced by plumes clusters and thermochemical piles are mostly unaffected. For all the values of Delta eta(pPv) we tested, long-wavelength CMB topography and reconstructed shear-wave tomography are anticorrelated in purely thermal models, and correlated in thermochemical models with strong chemical density contrast (Delta rho(C) = 140 kg/m(3)). In models with smaller density contrast (Delta rho(C) = 90 kg/m(3)), topography and tomography are anticorrelated at Delta eta(pPv) = 1, but correlated at Delta eta(pPv) = 10(-3).
Keywordconvection mantle dynamics core-mantle boundary topography postperovskite
DOI10.1029/2019JB017859
Funding OrganizationAcademia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program
WOS KeywordPOST-PEROVSKITE PHASE ; FREE-OSCILLATION SPECTRA ; PRIMORDIAL RESERVOIRS ; NORMAL-MODE ; THERMOCHEMICAL CONVECTION ; TRAVEL-TIMES ; CONSTRAINTS ; DENSITY ; VELOCITY ; STABILITY
Language英语
Funding ProjectAcademia Sinica Investigator Award[AS-IA-108-M03] ; Ministry of Science and Technology (MoST) of Taiwan[107-2116-M-001-010] ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program
Funding OrganizationAcademia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Academia Sinica Investigator Award ; Academia Sinica Investigator Award ; Ministry of Science and Technology (MoST) of Taiwan ; Ministry of Science and Technology (MoST) of Taiwan ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program ; Chinese Academy of Sciences (CAS) Pioneer Hundred Talent Program
WOS Research AreaGeochemistry & Geophysics
WOS SubjectGeochemistry & Geophysics
WOS IDWOS:000491283500088
PublisherAMER GEOPHYSICAL UNION
Citation statistics
Document Type期刊论文
Identifierhttp://ir.iggcas.ac.cn/handle/132A11/95758
Collection岩石圈演化国家重点实验室
Corresponding AuthorDeschamps, Frederic
Affiliation1.Acad Sin, Inst Earth Sci, Taipei, Taiwan
2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing, Peoples R China
Recommended Citation
GB/T 7714
Deschamps, Frederic,Li, Yang. Core-Mantle Boundary Dynamic Topography: Influence of Postperovskite Viscosity[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2019,124(8):9247-9264.
APA Deschamps, Frederic,&Li, Yang.(2019).Core-Mantle Boundary Dynamic Topography: Influence of Postperovskite Viscosity.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,124(8),9247-9264.
MLA Deschamps, Frederic,et al."Core-Mantle Boundary Dynamic Topography: Influence of Postperovskite Viscosity".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 124.8(2019):9247-9264.
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