High-pressure phase transitions of anorthosite crust in the Earth's deep mantle
We investigated phase relations, mineral chemistry, and density of lunar highland anorthosite at conditions up to 125 GPa and 2000 K. We used a multi-anvil apparatus and a laser-heated diamond-anvil cell for this purpose. In-situ X-ray diffraction measurements at high pressures and composition analy...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2018-11-01
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| Series: | Geoscience Frontiers |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987117301676 |
| _version_ | 1797723291560968192 |
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| author | Masayuki Nishi Steeve Gréaux Shigehiko Tateno Yasuhiro Kuwayama Kenji Kawai Tetsuo Irifune Shigenori Maruyama |
| author_facet | Masayuki Nishi Steeve Gréaux Shigehiko Tateno Yasuhiro Kuwayama Kenji Kawai Tetsuo Irifune Shigenori Maruyama |
| author_sort | Masayuki Nishi |
| collection | DOAJ |
| description | We investigated phase relations, mineral chemistry, and density of lunar highland anorthosite at conditions up to 125 GPa and 2000 K. We used a multi-anvil apparatus and a laser-heated diamond-anvil cell for this purpose. In-situ X-ray diffraction measurements at high pressures and composition analysis of recovered samples using an analytical transmission electron microscope showed that anorthosite consists of garnet, CaAl4Si2O11-rich phase (CAS phase), and SiO2 phases in the upper mantle and the mantle transition zone. Under lower mantle conditions, these minerals transform to the assemblage of bridgmanite, Ca-perovskite, corundum, stishovite, and calcium ferrite-type aluminous phase through the decomposition of garnet and CAS phase at around 700 km depth. Anorthosite has a higher density than PREM and pyrolite in the upper mantle, while its density becomes comparable or lower under lower mantle conditions. Our results suggest that ancient anorthosite crust subducted down to the deep mantle was likely to have accumulated at 660–720 km in depth without coming back to the Earth's surface. Some portions of the anorthosite crust might have circulated continuously in the Earth's deep interior by mantle convection and potentially subducted to the bottom of the lower mantle when carried within layers of dense basaltic rocks. Keywords: Anorthosite, Phase transformation, Multi-anvil apparatus, Diamond-anvil cell, Mantle dynamics |
| first_indexed | 2024-03-12T09:59:45Z |
| format | Article |
| id | doaj.art-d127b0ff2e324e0c8c1c1b63dca271dd |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T09:59:45Z |
| publishDate | 2018-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-d127b0ff2e324e0c8c1c1b63dca271dd2023-09-02T11:48:12ZengElsevierGeoscience Frontiers1674-98712018-11-019618591870High-pressure phase transitions of anorthosite crust in the Earth's deep mantleMasayuki Nishi0Steeve Gréaux1Shigehiko Tateno2Yasuhiro Kuwayama3Kenji Kawai4Tetsuo Irifune5Shigenori Maruyama6Geodynamics Research Centre, Ehime University, Ehime 790-8577, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan; Corresponding author. Geodynamics Research Centre, Ehime University, Ehime 790-8577, Japan.Geodynamics Research Centre, Ehime University, Ehime 790-8577, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, JapanEarth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan; Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, JapanGeodynamics Research Centre, Ehime University, Ehime 790-8577, Japan; Department of Earth Planetary Science, School of Science, University of Tokyo, 113-0033 Hongo 7-3-1, Bunkyo, Tokyo, JapanEarth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan; Department of Earth Planetary Science, School of Science, University of Tokyo, 113-0033 Hongo 7-3-1, Bunkyo, Tokyo, JapanGeodynamics Research Centre, Ehime University, Ehime 790-8577, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, JapanEarth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan; Novosibirsk State University, Pirogova 1, 630090, RussiaWe investigated phase relations, mineral chemistry, and density of lunar highland anorthosite at conditions up to 125 GPa and 2000 K. We used a multi-anvil apparatus and a laser-heated diamond-anvil cell for this purpose. In-situ X-ray diffraction measurements at high pressures and composition analysis of recovered samples using an analytical transmission electron microscope showed that anorthosite consists of garnet, CaAl4Si2O11-rich phase (CAS phase), and SiO2 phases in the upper mantle and the mantle transition zone. Under lower mantle conditions, these minerals transform to the assemblage of bridgmanite, Ca-perovskite, corundum, stishovite, and calcium ferrite-type aluminous phase through the decomposition of garnet and CAS phase at around 700 km depth. Anorthosite has a higher density than PREM and pyrolite in the upper mantle, while its density becomes comparable or lower under lower mantle conditions. Our results suggest that ancient anorthosite crust subducted down to the deep mantle was likely to have accumulated at 660–720 km in depth without coming back to the Earth's surface. Some portions of the anorthosite crust might have circulated continuously in the Earth's deep interior by mantle convection and potentially subducted to the bottom of the lower mantle when carried within layers of dense basaltic rocks. Keywords: Anorthosite, Phase transformation, Multi-anvil apparatus, Diamond-anvil cell, Mantle dynamicshttp://www.sciencedirect.com/science/article/pii/S1674987117301676 |
| spellingShingle | Masayuki Nishi Steeve Gréaux Shigehiko Tateno Yasuhiro Kuwayama Kenji Kawai Tetsuo Irifune Shigenori Maruyama High-pressure phase transitions of anorthosite crust in the Earth's deep mantle Geoscience Frontiers |
| title | High-pressure phase transitions of anorthosite crust in the Earth's deep mantle |
| title_full | High-pressure phase transitions of anorthosite crust in the Earth's deep mantle |
| title_fullStr | High-pressure phase transitions of anorthosite crust in the Earth's deep mantle |
| title_full_unstemmed | High-pressure phase transitions of anorthosite crust in the Earth's deep mantle |
| title_short | High-pressure phase transitions of anorthosite crust in the Earth's deep mantle |
| title_sort | high pressure phase transitions of anorthosite crust in the earth s deep mantle |
| url | http://www.sciencedirect.com/science/article/pii/S1674987117301676 |
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