Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean
Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been much less studied than those from the Indian, Atlantic, and Pacific due to the difficulty of access related to ice cover. In 2001 and 2004 the Arctic ridges (Gakkel Ridge and Lena Trough) were intensively sampled. In this study we presen...
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ftlouisianastuir:oai:digitalcommons.lsu.edu:geo_pubs-1984 2023-06-11T04:08:52+02:00 Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean Nauret, F. Moreira, M. Snow, S. E. 2010-06-01T07:00:00Z application/pdf https://digitalcommons.lsu.edu/geo_pubs/985 https://doi.org/10.1029/2010GC003027 https://digitalcommons.lsu.edu/context/geo_pubs/article/1984/viewcontent/985.pdf unknown LSU Digital Commons https://digitalcommons.lsu.edu/geo_pubs/985 doi:10.1029/2010GC003027 https://digitalcommons.lsu.edu/context/geo_pubs/article/1984/viewcontent/985.pdf Faculty Publications DUPAL anomaly Mantle heterogeneity MORB Noble gases text 2010 ftlouisianastuir https://doi.org/10.1029/2010GC003027 2023-05-28T18:24:17Z Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been much less studied than those from the Indian, Atlantic, and Pacific due to the difficulty of access related to ice cover. In 2001 and 2004 the Arctic ridges (Gakkel Ridge and Lena Trough) were intensively sampled. In this study we present the first helium, neon, and argon concentrations and isotopic ratios in a suite of samples from the ultraslow spreading Lena Trough (~0.75 cm/yr effective full rate). Central Lena Trough (CLT) lavas display 4He/3He between 89,710 and 97,530 (R/Ra between 7.4 and 8.1), similar to the mean MORB ratio of 90,000 10,000 (R/Ra = 8 1). In a three neon isotope diagram, the samples fall on the MORB line, without showing any excess of nucleogenic 21Ne. The 40Ar/36Ar ratios vary from 349 to 6964. CLT samples have a typical MORB He and Ne isotopic composition. Rare gases do not indicate any mantle heterogeneities or contribution of subcontinental lithospheric mantle, although this has been suggested previously on the basis of the Sr-Nd and Pb isotopic systems. Based on noble gas systematics, a DUPAL-like anomaly is not observed in the Arctic Ocean. We propose two possible models which reconcile the rare gases with these previous studies. The first is that the Lena Trough mantle has a marble cake structure with small-scale heterogeneities (<1 >km), allowing rapid diffusion and homogenization of rare gases compared to elements such as Sr, Nd, and Pb. The second model proposes that the recycled component identified by other isotopic systems was fully degassed at a recent date. It would therefore have a negligible mass budget of rare gases compared to other isotopic systems. This would suggest that the mantle enrichment beneath Lena Trough was generated by rift-forming processes and not by recycling. Copyright 2010 by the American Geophysical Union. Text Arctic Arctic Ocean LSU Digital Commons (Louisiana State University) Arctic Arctic Ocean Pacific Indian Gakkel Ridge ENVELOPE(90.000,90.000,87.000,87.000) Geochemistry, Geophysics, Geosystems 11 6 n/a n/a |
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Open Polar |
collection |
LSU Digital Commons (Louisiana State University) |
op_collection_id |
ftlouisianastuir |
language |
unknown |
topic |
DUPAL anomaly Mantle heterogeneity MORB Noble gases |
spellingShingle |
DUPAL anomaly Mantle heterogeneity MORB Noble gases Nauret, F. Moreira, M. Snow, S. E. Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
topic_facet |
DUPAL anomaly Mantle heterogeneity MORB Noble gases |
description |
Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been much less studied than those from the Indian, Atlantic, and Pacific due to the difficulty of access related to ice cover. In 2001 and 2004 the Arctic ridges (Gakkel Ridge and Lena Trough) were intensively sampled. In this study we present the first helium, neon, and argon concentrations and isotopic ratios in a suite of samples from the ultraslow spreading Lena Trough (~0.75 cm/yr effective full rate). Central Lena Trough (CLT) lavas display 4He/3He between 89,710 and 97,530 (R/Ra between 7.4 and 8.1), similar to the mean MORB ratio of 90,000 10,000 (R/Ra = 8 1). In a three neon isotope diagram, the samples fall on the MORB line, without showing any excess of nucleogenic 21Ne. The 40Ar/36Ar ratios vary from 349 to 6964. CLT samples have a typical MORB He and Ne isotopic composition. Rare gases do not indicate any mantle heterogeneities or contribution of subcontinental lithospheric mantle, although this has been suggested previously on the basis of the Sr-Nd and Pb isotopic systems. Based on noble gas systematics, a DUPAL-like anomaly is not observed in the Arctic Ocean. We propose two possible models which reconcile the rare gases with these previous studies. The first is that the Lena Trough mantle has a marble cake structure with small-scale heterogeneities (<1 >km), allowing rapid diffusion and homogenization of rare gases compared to elements such as Sr, Nd, and Pb. The second model proposes that the recycled component identified by other isotopic systems was fully degassed at a recent date. It would therefore have a negligible mass budget of rare gases compared to other isotopic systems. This would suggest that the mantle enrichment beneath Lena Trough was generated by rift-forming processes and not by recycling. Copyright 2010 by the American Geophysical Union. |
format |
Text |
author |
Nauret, F. Moreira, M. Snow, S. E. |
author_facet |
Nauret, F. Moreira, M. Snow, S. E. |
author_sort |
Nauret, F. |
title |
Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
title_short |
Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
title_full |
Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
title_fullStr |
Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
title_full_unstemmed |
Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean |
title_sort |
rare gases in lavas from the ultraslow spreading lena trough, arctic ocean |
publisher |
LSU Digital Commons |
publishDate |
2010 |
url |
https://digitalcommons.lsu.edu/geo_pubs/985 https://doi.org/10.1029/2010GC003027 https://digitalcommons.lsu.edu/context/geo_pubs/article/1984/viewcontent/985.pdf |
long_lat |
ENVELOPE(90.000,90.000,87.000,87.000) |
geographic |
Arctic Arctic Ocean Pacific Indian Gakkel Ridge |
geographic_facet |
Arctic Arctic Ocean Pacific Indian Gakkel Ridge |
genre |
Arctic Arctic Ocean |
genre_facet |
Arctic Arctic Ocean |
op_source |
Faculty Publications |
op_relation |
https://digitalcommons.lsu.edu/geo_pubs/985 doi:10.1029/2010GC003027 https://digitalcommons.lsu.edu/context/geo_pubs/article/1984/viewcontent/985.pdf |
op_doi |
https://doi.org/10.1029/2010GC003027 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
11 |
container_issue |
6 |
container_start_page |
n/a |
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n/a |
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1768382483193135104 |