Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe
Until recently, most of the lower mantle was generally considered to be well-mixed with strong heterogeneity restricted to the lowermost several hundred kilometres above the core–mantle boundary, known as the D″D″ layer. However several recent studies have started to hint at a potential change in Ea...
Published in: | Earth and Planetary Science Letters |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier
2016
|
Subjects: | |
Online Access: | http://eprints.esc.cam.ac.uk/3749/ http://eprints.esc.cam.ac.uk/3749/1/1-s2.0-S0012821X16306653-main.pdf http://eprints.esc.cam.ac.uk/3749/2/mmc1.pdf http://eprints.esc.cam.ac.uk/3749/3/mmc2.txt http://eprints.esc.cam.ac.uk/3749/4/mmc3.txt http://www.sciencedirect.com/science/article/pii/S0012821X16306653 https://doi.org/10.1016/j.epsl.2016.11.031 |
id |
ftucambridgeesc:oai:eprints.esc.cam.ac.uk:3749 |
---|---|
record_format |
openpolar |
spelling |
ftucambridgeesc:oai:eprints.esc.cam.ac.uk:3749 2023-05-15T16:49:40+02:00 Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe Jenkins, Jennifer Deuss, Arwen Cottaar, Sanne 2016-08 text http://eprints.esc.cam.ac.uk/3749/ http://eprints.esc.cam.ac.uk/3749/1/1-s2.0-S0012821X16306653-main.pdf http://eprints.esc.cam.ac.uk/3749/2/mmc1.pdf http://eprints.esc.cam.ac.uk/3749/3/mmc2.txt http://eprints.esc.cam.ac.uk/3749/4/mmc3.txt http://www.sciencedirect.com/science/article/pii/S0012821X16306653 https://doi.org/10.1016/j.epsl.2016.11.031 en eng Elsevier http://eprints.esc.cam.ac.uk/3749/1/1-s2.0-S0012821X16306653-main.pdf http://eprints.esc.cam.ac.uk/3749/2/mmc1.pdf http://eprints.esc.cam.ac.uk/3749/3/mmc2.txt http://eprints.esc.cam.ac.uk/3749/4/mmc3.txt Jenkins, Jennifer and Deuss, Arwen and Cottaar, Sanne (2016) Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe. Earth and Planetary Science Letters, 459. ISSN 0012-821X DOI https://doi.org/10.1016/j.epsl.2016.11.031 <https://doi.org/10.1016/j.epsl.2016.11.031> cc_by CC-BY 02 - Geodynamics Geophysics and Tectonics Article PeerReviewed 2016 ftucambridgeesc https://doi.org/10.1016/j.epsl.2016.11.031 2020-08-27T18:09:47Z Until recently, most of the lower mantle was generally considered to be well-mixed with strong heterogeneity restricted to the lowermost several hundred kilometres above the core–mantle boundary, known as the D″D″ layer. However several recent studies have started to hint at a potential change in Earth's structure at mid-mantle depths beneath the transition zone. Here we present a continental-wide search of Europe and the North Atlantic for mid-mantle P-to-s wave converted phases. Our data set consists of close to 50,000 high quality receiver functions. These are combined in slowness and depth stacks to identify seismic discontinuities in the range of 800–1400 km depth to determine at which depths and in which tectonic settings these features exist. Receiver functions are computed in different frequency bands to resolve the sharpness of the observed discontinuities. We find most seismic velocity jumps are observed between 975–1050 km depth, localised beneath western Europe and Iceland. The shear wave velocity jumps are roughly 1–2.5% velocity increase with depth occurring over less than 8 km in width. The most robust observations are coincident with areas of active upwelling (under Iceland) and an elongate lateral low velocity anomaly imaged in recent tomographic models which has been interpreted as diverted plume material at depth. The lack of any suggested phase change in a normal pyrolitic mantle composition at around 1000 km depth indicates the presence of regional chemical heterogeneity within the mid-mantle, potentially caused by diverted plume material. We hypothesise that our observations represent either a phase change within chemically distinct plume material itself, or are caused by small scale chemical heterogeneities entrained within the upwelling plume, either in the form of recycled basaltic material or deep sourced chemically distinct material from LLSVPs. Our observations, which cannot be directly linked to an area of either active or ancient subduction, along with observations in other hotspot regions, suggest that such mid-mantle seismic features are not unique to subduction zones despite the large number of observations that have previously been made in such settings. Article in Journal/Newspaper Iceland North Atlantic University of Cambridge, Department of Earth Sciences: ESC Publications Earth and Planetary Science Letters 459 196 207 |
institution |
Open Polar |
collection |
University of Cambridge, Department of Earth Sciences: ESC Publications |
op_collection_id |
ftucambridgeesc |
language |
English |
topic |
02 - Geodynamics Geophysics and Tectonics |
spellingShingle |
02 - Geodynamics Geophysics and Tectonics Jenkins, Jennifer Deuss, Arwen Cottaar, Sanne Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
topic_facet |
02 - Geodynamics Geophysics and Tectonics |
description |
Until recently, most of the lower mantle was generally considered to be well-mixed with strong heterogeneity restricted to the lowermost several hundred kilometres above the core–mantle boundary, known as the D″D″ layer. However several recent studies have started to hint at a potential change in Earth's structure at mid-mantle depths beneath the transition zone. Here we present a continental-wide search of Europe and the North Atlantic for mid-mantle P-to-s wave converted phases. Our data set consists of close to 50,000 high quality receiver functions. These are combined in slowness and depth stacks to identify seismic discontinuities in the range of 800–1400 km depth to determine at which depths and in which tectonic settings these features exist. Receiver functions are computed in different frequency bands to resolve the sharpness of the observed discontinuities. We find most seismic velocity jumps are observed between 975–1050 km depth, localised beneath western Europe and Iceland. The shear wave velocity jumps are roughly 1–2.5% velocity increase with depth occurring over less than 8 km in width. The most robust observations are coincident with areas of active upwelling (under Iceland) and an elongate lateral low velocity anomaly imaged in recent tomographic models which has been interpreted as diverted plume material at depth. The lack of any suggested phase change in a normal pyrolitic mantle composition at around 1000 km depth indicates the presence of regional chemical heterogeneity within the mid-mantle, potentially caused by diverted plume material. We hypothesise that our observations represent either a phase change within chemically distinct plume material itself, or are caused by small scale chemical heterogeneities entrained within the upwelling plume, either in the form of recycled basaltic material or deep sourced chemically distinct material from LLSVPs. Our observations, which cannot be directly linked to an area of either active or ancient subduction, along with observations in other hotspot regions, suggest that such mid-mantle seismic features are not unique to subduction zones despite the large number of observations that have previously been made in such settings. |
format |
Article in Journal/Newspaper |
author |
Jenkins, Jennifer Deuss, Arwen Cottaar, Sanne |
author_facet |
Jenkins, Jennifer Deuss, Arwen Cottaar, Sanne |
author_sort |
Jenkins, Jennifer |
title |
Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
title_short |
Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
title_full |
Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
title_fullStr |
Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
title_full_unstemmed |
Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe |
title_sort |
converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath western europe |
publisher |
Elsevier |
publishDate |
2016 |
url |
http://eprints.esc.cam.ac.uk/3749/ http://eprints.esc.cam.ac.uk/3749/1/1-s2.0-S0012821X16306653-main.pdf http://eprints.esc.cam.ac.uk/3749/2/mmc1.pdf http://eprints.esc.cam.ac.uk/3749/3/mmc2.txt http://eprints.esc.cam.ac.uk/3749/4/mmc3.txt http://www.sciencedirect.com/science/article/pii/S0012821X16306653 https://doi.org/10.1016/j.epsl.2016.11.031 |
genre |
Iceland North Atlantic |
genre_facet |
Iceland North Atlantic |
op_relation |
http://eprints.esc.cam.ac.uk/3749/1/1-s2.0-S0012821X16306653-main.pdf http://eprints.esc.cam.ac.uk/3749/2/mmc1.pdf http://eprints.esc.cam.ac.uk/3749/3/mmc2.txt http://eprints.esc.cam.ac.uk/3749/4/mmc3.txt Jenkins, Jennifer and Deuss, Arwen and Cottaar, Sanne (2016) Converted phases from sharp 1000 km depth mid-mantle heterogeneity beneath Western Europe. Earth and Planetary Science Letters, 459. ISSN 0012-821X DOI https://doi.org/10.1016/j.epsl.2016.11.031 <https://doi.org/10.1016/j.epsl.2016.11.031> |
op_rights |
cc_by |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/j.epsl.2016.11.031 |
container_title |
Earth and Planetary Science Letters |
container_volume |
459 |
container_start_page |
196 |
op_container_end_page |
207 |
_version_ |
1766039844503420928 |