Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge)
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 21 (2006): PA3012, doi:10.1029/2006PA001273. Geochemical compositions and Sr...
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/1261 2023-05-15T16:52:48+02:00 Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) Chavagnac, Valerie Palmer, Martin R. Milton, J. Andrew Green, Darryl R. H. German, Christopher R. 2006-09-09 application/pdf https://hdl.handle.net/1912/1261 en_US eng American Geophysical Union https://doi.org/10.1029/2006PA001273 Paleoceanography 21 (2006): PA3012 https://hdl.handle.net/1912/1261 doi:10.1029/2006PA001273 Paleoceanography 21 (2006): PA3012 doi:10.1029/2006PA001273 Nd isotope Hydrothermal Seawater Article 2006 ftwhoas https://doi.org/10.1029/2006PA001273 2022-05-28T22:57:10Z Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 21 (2006): PA3012, doi:10.1029/2006PA001273. Geochemical compositions and Sr and Nd isotopes were measured in two cores collected ~2 and 5 km from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge. Overall, the cores record enrichments in Fe and other metals from hydrothermal fallout, but sequential dissolution of the sediments allows discrimination between a leach phase (easily leachable) and a residue phase (refractory). The oxy-anion and transition metal distribution combined with rare earth element (REE) patterns suggest that 1) the leach fraction is a mixture of biogenic carbonate and hydrothermal Fe-Mn oxy-hydroxide with no significant contribution from detrital material, and 2) >99.5% of the REE content of the leach fraction is of seawater origin. In addition, the leach fraction has an average 87Sr/86Sr ratio indistinguishable from modern seawater at 0.70916. Although we lack the εNd value of present day deep water at the Rainbow vent site, we believe that the REE budget of the leach fraction is predominantly of seawater origin. We suggest, therefore, that the leach fraction provides a record of local seawater εNd values. Nd isotope data from these cores span the period of 4-14 ka (14C ages) and yield εNd values for North East Atlantic Deep Water (NEADW) that are higher (-9.3 to -11.1) than those observed in the nearby Madeira Abyssal Plain from the same depth (-12.4 ± 0.9). This observation suggests that either the Iceland-Scotland Overflow Water (ISOW) and Lower Deep Water (LDW) contributions to the formation of NEADW are higher along the Mid-Atlantic Ridge than in the surrounding basins, or that the relative proportion of ISOW was higher during this period than is observed today. This study indicates that hydrothermal sediments have the potential to provide a higher ... Article in Journal/Newspaper Iceland North East Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Mid-Atlantic Ridge Paleoceanography 21 3 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Nd isotope Hydrothermal Seawater |
spellingShingle |
Nd isotope Hydrothermal Seawater Chavagnac, Valerie Palmer, Martin R. Milton, J. Andrew Green, Darryl R. H. German, Christopher R. Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
topic_facet |
Nd isotope Hydrothermal Seawater |
description |
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 21 (2006): PA3012, doi:10.1029/2006PA001273. Geochemical compositions and Sr and Nd isotopes were measured in two cores collected ~2 and 5 km from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge. Overall, the cores record enrichments in Fe and other metals from hydrothermal fallout, but sequential dissolution of the sediments allows discrimination between a leach phase (easily leachable) and a residue phase (refractory). The oxy-anion and transition metal distribution combined with rare earth element (REE) patterns suggest that 1) the leach fraction is a mixture of biogenic carbonate and hydrothermal Fe-Mn oxy-hydroxide with no significant contribution from detrital material, and 2) >99.5% of the REE content of the leach fraction is of seawater origin. In addition, the leach fraction has an average 87Sr/86Sr ratio indistinguishable from modern seawater at 0.70916. Although we lack the εNd value of present day deep water at the Rainbow vent site, we believe that the REE budget of the leach fraction is predominantly of seawater origin. We suggest, therefore, that the leach fraction provides a record of local seawater εNd values. Nd isotope data from these cores span the period of 4-14 ka (14C ages) and yield εNd values for North East Atlantic Deep Water (NEADW) that are higher (-9.3 to -11.1) than those observed in the nearby Madeira Abyssal Plain from the same depth (-12.4 ± 0.9). This observation suggests that either the Iceland-Scotland Overflow Water (ISOW) and Lower Deep Water (LDW) contributions to the formation of NEADW are higher along the Mid-Atlantic Ridge than in the surrounding basins, or that the relative proportion of ISOW was higher during this period than is observed today. This study indicates that hydrothermal sediments have the potential to provide a higher ... |
format |
Article in Journal/Newspaper |
author |
Chavagnac, Valerie Palmer, Martin R. Milton, J. Andrew Green, Darryl R. H. German, Christopher R. |
author_facet |
Chavagnac, Valerie Palmer, Martin R. Milton, J. Andrew Green, Darryl R. H. German, Christopher R. |
author_sort |
Chavagnac, Valerie |
title |
Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
title_short |
Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
title_full |
Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
title_fullStr |
Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
title_full_unstemmed |
Hydrothermal sediments as a potential record of seawater Nd isotope compositions : the Rainbow vent site (36°14′N, Mid-Atlantic Ridge) |
title_sort |
hydrothermal sediments as a potential record of seawater nd isotope compositions : the rainbow vent site (36°14′n, mid-atlantic ridge) |
publisher |
American Geophysical Union |
publishDate |
2006 |
url |
https://hdl.handle.net/1912/1261 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
Iceland North East Atlantic |
genre_facet |
Iceland North East Atlantic |
op_source |
Paleoceanography 21 (2006): PA3012 doi:10.1029/2006PA001273 |
op_relation |
https://doi.org/10.1029/2006PA001273 Paleoceanography 21 (2006): PA3012 https://hdl.handle.net/1912/1261 doi:10.1029/2006PA001273 |
op_doi |
https://doi.org/10.1029/2006PA001273 |
container_title |
Paleoceanography |
container_volume |
21 |
container_issue |
3 |
_version_ |
1766043232271073280 |