From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic
Abstract The distribution of Ultra‐low Velocity Zones (ULVZs) is generally associated with the Large Low Shear Velocity Zones (LLSVPs). However, subducted slabs may be important for the characteristics of the ULVZs as well. Here we use ScS precursor (SdS) and postcursor (ScscS) phases, as well as Sc...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2022-01-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Online Access: | https://doi.org/10.1029/2021GC009879 |
| _version_ | 1797637954043117568 |
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| author | An Fan Xinlei Sun Zhou Zhang Peng Zhang Jianye Zong |
| author_facet | An Fan Xinlei Sun Zhou Zhang Peng Zhang Jianye Zong |
| author_sort | An Fan |
| collection | DOAJ |
| description | Abstract The distribution of Ultra‐low Velocity Zones (ULVZs) is generally associated with the Large Low Shear Velocity Zones (LLSVPs). However, subducted slabs may be important for the characteristics of the ULVZs as well. Here we use ScS precursor (SdS) and postcursor (ScscS) phases, as well as Scd phases recorded by USArray to investigate the lowermost mantle structure across the north Atlantic, which spans the African LLSVP and the subducted Farallon slab. Our results show a ULVZ located near the edge of the African LLSVP, with thicknesses ranging from 11–16 km and S wave velocity reductions of 12%–24%. At the same time, a thin high‐velocity layer (HVL) with thicknesses of 20–30 km, Vs increases of 3%–4%, is also detected outside the LLSVP in the northwest region. Further west there is a clear D" layer at 250 km above the core mantle boundary (CMB), overlaid by a low velocity layer with Vs reduction of 3%. This transition profile from D" to HVL to ULVZ provides an excellent opportunity for us to understand the heterogeneities near the CMB region. We propose that interactions between the subducted Farallon slab with ambient mantle and LLSVP material, together with thermal effects, may result in this transition between different seismic structures along the CMB. |
| first_indexed | 2024-03-11T12:55:40Z |
| format | Article |
| id | doaj.art-848e13dd30594772b58696b4adf53295 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:55:40Z |
| publishDate | 2022-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-848e13dd30594772b58696b4adf532952023-11-03T17:01:12ZengWileyGeochemistry, Geophysics, Geosystems1525-20272022-01-01231n/an/a10.1029/2021GC009879From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North AtlanticAn Fan0Xinlei Sun1Zhou Zhang2Peng Zhang3Jianye Zong4State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou ChinaState Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou ChinaState Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou ChinaState Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou ChinaInternational Center for Planetary Science College of Geosciences Chengdu University of Technology Chengdu ChinaAbstract The distribution of Ultra‐low Velocity Zones (ULVZs) is generally associated with the Large Low Shear Velocity Zones (LLSVPs). However, subducted slabs may be important for the characteristics of the ULVZs as well. Here we use ScS precursor (SdS) and postcursor (ScscS) phases, as well as Scd phases recorded by USArray to investigate the lowermost mantle structure across the north Atlantic, which spans the African LLSVP and the subducted Farallon slab. Our results show a ULVZ located near the edge of the African LLSVP, with thicknesses ranging from 11–16 km and S wave velocity reductions of 12%–24%. At the same time, a thin high‐velocity layer (HVL) with thicknesses of 20–30 km, Vs increases of 3%–4%, is also detected outside the LLSVP in the northwest region. Further west there is a clear D" layer at 250 km above the core mantle boundary (CMB), overlaid by a low velocity layer with Vs reduction of 3%. This transition profile from D" to HVL to ULVZ provides an excellent opportunity for us to understand the heterogeneities near the CMB region. We propose that interactions between the subducted Farallon slab with ambient mantle and LLSVP material, together with thermal effects, may result in this transition between different seismic structures along the CMB.https://doi.org/10.1029/2021GC009879 |
| spellingShingle | An Fan Xinlei Sun Zhou Zhang Peng Zhang Jianye Zong From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic Geochemistry, Geophysics, Geosystems |
| title | From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic |
| title_full | From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic |
| title_fullStr | From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic |
| title_full_unstemmed | From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic |
| title_short | From Subduction to LLSVP: The Core‐Mantle Boundary Heterogeneities Across North Atlantic |
| title_sort | from subduction to llsvp the core mantle boundary heterogeneities across north atlantic |
| url | https://doi.org/10.1029/2021GC009879 |
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