Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle
Abstract Numerical experiments of thermochemical mantle convection in 2‐D spherical annulus geometry are performed to investigate the effects of compositional viscosity ratio (ΔηC) on the long‐term evolution of reservoirs of dense, primordial material in the lowermost mantle of the Earth. The intern...
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| Format: | Article |
| Language: | English |
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Wiley
2019-08-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2019GL083668 |
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| author | Yang Li Frédéric Deschamps Jianfeng Yang Lin Chen Liang Zhao Paul J. Tackley |
| author_facet | Yang Li Frédéric Deschamps Jianfeng Yang Lin Chen Liang Zhao Paul J. Tackley |
| author_sort | Yang Li |
| collection | DOAJ |
| description | Abstract Numerical experiments of thermochemical mantle convection in 2‐D spherical annulus geometry are performed to investigate the effects of compositional viscosity ratio (ΔηC) on the long‐term evolution of reservoirs of dense, primordial material in the lowermost mantle of the Earth. The internal heating rate in the primordial material is larger than in the ambient mantle by a factor of 10, accounting for the fact that this material may be enriched in radiogenic elements. We find that if the chemical density contrast is large (128 kg/m3), ΔηC plays only a second‐order role on the long‐term stability of these reservoirs. As the chemical density contrast decreases to smaller values (90 kg/m3), ΔηC plays a more significant role. More specifically, when ΔηC is large, around 10 or larger, convection within the reservoirs of primordial material is less vigorous, which increases the temperature and thermal buoyancy of these structures. This, in turn, can eventually lead them to become unstable, with the majority of the primordial material being advected into the large‐scale mantle circulation. |
| format | Article |
| id | doaj-art-e3fd2938fe5f4979ba3be241129f0831 |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2019-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-e3fd2938fe5f4979ba3be241129f08312025-08-20T02:24:35ZengWileyGeophysical Research Letters0094-82761944-80072019-08-0146169591960110.1029/2019GL083668Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep MantleYang Li0Frédéric Deschamps1Jianfeng Yang2Lin Chen3Liang Zhao4Paul J. Tackley5Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics Chinese Academy of Sciences Beijing ChinaInstitute of Earth Sciences Academia Sinica Taipei TaiwanState Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics Chinese Academy of Sciences Beijing ChinaState Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics Chinese Academy of Sciences Beijing ChinaState Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics Chinese Academy of Sciences Beijing ChinaInstitute of Geophysics, Department of Earth Sciences ETH Zurich Zurich SwitzerlandAbstract Numerical experiments of thermochemical mantle convection in 2‐D spherical annulus geometry are performed to investigate the effects of compositional viscosity ratio (ΔηC) on the long‐term evolution of reservoirs of dense, primordial material in the lowermost mantle of the Earth. The internal heating rate in the primordial material is larger than in the ambient mantle by a factor of 10, accounting for the fact that this material may be enriched in radiogenic elements. We find that if the chemical density contrast is large (128 kg/m3), ΔηC plays only a second‐order role on the long‐term stability of these reservoirs. As the chemical density contrast decreases to smaller values (90 kg/m3), ΔηC plays a more significant role. More specifically, when ΔηC is large, around 10 or larger, convection within the reservoirs of primordial material is less vigorous, which increases the temperature and thermal buoyancy of these structures. This, in turn, can eventually lead them to become unstable, with the majority of the primordial material being advected into the large‐scale mantle circulation.https://doi.org/10.1029/2019GL083668mantle convectionheterogeneous internal heating ratelower mantlecompositional viscosity ratioprimordial reservoirs |
| spellingShingle | Yang Li Frédéric Deschamps Jianfeng Yang Lin Chen Liang Zhao Paul J. Tackley Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle Geophysical Research Letters mantle convection heterogeneous internal heating rate lower mantle compositional viscosity ratio primordial reservoirs |
| title | Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle |
| title_full | Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle |
| title_fullStr | Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle |
| title_full_unstemmed | Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle |
| title_short | Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle |
| title_sort | effects of the compositional viscosity ratio on the long term evolution of thermochemical reservoirs in the deep mantle |
| topic | mantle convection heterogeneous internal heating rate lower mantle compositional viscosity ratio primordial reservoirs |
| url | https://doi.org/10.1029/2019GL083668 |
| work_keys_str_mv | AT yangli effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle AT fredericdeschamps effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle AT jianfengyang effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle AT linchen effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle AT liangzhao effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle AT pauljtackley effectsofthecompositionalviscosityratioonthelongtermevolutionofthermochemicalreservoirsinthedeepmantle |