A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge
The Mohns Ridge is a very slow-spreading ridge that, together with the Knipovich Ridge, marks the boundary between the North American and Eurasian plates in the Norwegian-Greenland Sea. In this study, we report the major and trace element composition of spatially associated basalts and peridotites f...
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Online Access: | https://hdl.handle.net/11250/3055043 https://doi.org/10.1029/2022GC010585 |
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ftunivbergen:oai:bora.uib.no:11250/3055043 2023-05-15T15:09:16+02:00 A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge Bjerga, Anders Stubseid, Håvard Hallås Pedersen, Leif-Erik Rydland Beinlich, Andreas Michael Pedersen, Rolf B. 2022 application/pdf https://hdl.handle.net/11250/3055043 https://doi.org/10.1029/2022GC010585 eng eng AGU urn:issn:1525-2027 https://hdl.handle.net/11250/3055043 https://doi.org/10.1029/2022GC010585 cristin:2092903 Geochemistry Geophysics Geosystems. 2022, 23 (11), e2022GC010585. Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2022 The Author(s) e2022GC010585 Geochemistry Geophysics Geosystems 23 11 Journal article Peer reviewed 2022 ftunivbergen https://doi.org/10.1029/2022GC010585 2023-03-14T17:39:20Z The Mohns Ridge is a very slow-spreading ridge that, together with the Knipovich Ridge, marks the boundary between the North American and Eurasian plates in the Norwegian-Greenland Sea. In this study, we report the major and trace element composition of spatially associated basalts and peridotites from a gabbro-peridotite complex ∼20 km west of the Mohns Ridge rift flank. Formation of the ∼4–5 Myr crustal section involved accretion of normal mid-ocean ridge basalts with Na-content suggesting derivation from a depleted mantle source. This is consistent with the degree of partial melting estimated for clinopyroxene poor harzburgites using the Cr-number of spinel (14%–18%) and rare earth element modeling of orthopyroxene (16%–24%) and reconstructed whole-rock composition (14%–20%). If all the melting took place beneath the paleo-Mohns Ridge, a crustal thickness of ∼7–8 km is expected, which is nearly double the observed thickness. Orthopyroxene trace elements are not consistent with typical fractional melting expected for mid-ocean ridges but rather resemble that seen in supra-subduction zone peridotites. The geochemistry of both the basalts and the peridotites suggests that a water-rich slab flux in the past has influenced the mantle source. In turn, this caused hydrous melting which increased the depletion of the pyroxene components, leading to a highly depleted mantle that is now underlying much of the Arctic Mid-Ocean Ridges and represents the source for the spreading related magmatism. publishedVersion Article in Journal/Newspaper Arctic Greenland Greenland Sea University of Bergen: Bergen Open Research Archive (BORA-UiB) Arctic Greenland Knipovich Ridge ENVELOPE(7.074,7.074,75.712,75.712) Geochemistry, Geophysics, Geosystems 23 11 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
description |
The Mohns Ridge is a very slow-spreading ridge that, together with the Knipovich Ridge, marks the boundary between the North American and Eurasian plates in the Norwegian-Greenland Sea. In this study, we report the major and trace element composition of spatially associated basalts and peridotites from a gabbro-peridotite complex ∼20 km west of the Mohns Ridge rift flank. Formation of the ∼4–5 Myr crustal section involved accretion of normal mid-ocean ridge basalts with Na-content suggesting derivation from a depleted mantle source. This is consistent with the degree of partial melting estimated for clinopyroxene poor harzburgites using the Cr-number of spinel (14%–18%) and rare earth element modeling of orthopyroxene (16%–24%) and reconstructed whole-rock composition (14%–20%). If all the melting took place beneath the paleo-Mohns Ridge, a crustal thickness of ∼7–8 km is expected, which is nearly double the observed thickness. Orthopyroxene trace elements are not consistent with typical fractional melting expected for mid-ocean ridges but rather resemble that seen in supra-subduction zone peridotites. The geochemistry of both the basalts and the peridotites suggests that a water-rich slab flux in the past has influenced the mantle source. In turn, this caused hydrous melting which increased the depletion of the pyroxene components, leading to a highly depleted mantle that is now underlying much of the Arctic Mid-Ocean Ridges and represents the source for the spreading related magmatism. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Bjerga, Anders Stubseid, Håvard Hallås Pedersen, Leif-Erik Rydland Beinlich, Andreas Michael Pedersen, Rolf B. |
spellingShingle |
Bjerga, Anders Stubseid, Håvard Hallås Pedersen, Leif-Erik Rydland Beinlich, Andreas Michael Pedersen, Rolf B. A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
author_facet |
Bjerga, Anders Stubseid, Håvard Hallås Pedersen, Leif-Erik Rydland Beinlich, Andreas Michael Pedersen, Rolf B. |
author_sort |
Bjerga, Anders |
title |
A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
title_short |
A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
title_full |
A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
title_fullStr |
A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
title_full_unstemmed |
A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge |
title_sort |
highly depleted and subduction-modified mantle beneath the slow-spreading mohns ridge |
publisher |
AGU |
publishDate |
2022 |
url |
https://hdl.handle.net/11250/3055043 https://doi.org/10.1029/2022GC010585 |
long_lat |
ENVELOPE(7.074,7.074,75.712,75.712) |
geographic |
Arctic Greenland Knipovich Ridge |
geographic_facet |
Arctic Greenland Knipovich Ridge |
genre |
Arctic Greenland Greenland Sea |
genre_facet |
Arctic Greenland Greenland Sea |
op_source |
e2022GC010585 Geochemistry Geophysics Geosystems 23 11 |
op_relation |
urn:issn:1525-2027 https://hdl.handle.net/11250/3055043 https://doi.org/10.1029/2022GC010585 cristin:2092903 Geochemistry Geophysics Geosystems. 2022, 23 (11), e2022GC010585. |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2022 The Author(s) |
op_doi |
https://doi.org/10.1029/2022GC010585 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
23 |
container_issue |
11 |
_version_ |
1766340484086628352 |