Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions
Hydrothermal circulation at slow-spreading ridges is important for cooling the newly formed lithosphere, but the depth to which it occurs is uncertain. Magmas which stagnate and partially crystallize during their rise from the mantle provide a means to constrain the depth of circulation because assi...
Published in: | Contributions to Mineralogy and Petrology |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2017
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Online Access: | https://oceanrep.geomar.de/id/eprint/40109/ https://oceanrep.geomar.de/id/eprint/40109/1/van%20der%20Zwan.pdf https://doi.org/10.1007/s00410-017-1418-1 |
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ftoceanrep:oai:oceanrep.geomar.de:40109 2023-05-15T14:27:47+02:00 Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions van der Zwan, Froukje M. Devey, Colin W. Hansteen, Thor H. Almeev, Renat R. Augustin, Nico Frische, Matthias Haase, Karsten M. Basaham, Ali Snow, Jonathan E. 2017-11-09 text https://oceanrep.geomar.de/id/eprint/40109/ https://oceanrep.geomar.de/id/eprint/40109/1/van%20der%20Zwan.pdf https://doi.org/10.1007/s00410-017-1418-1 en eng Springer https://oceanrep.geomar.de/id/eprint/40109/1/van%20der%20Zwan.pdf van der Zwan, F. M. , Devey, C. W. , Hansteen, T. H. , Almeev, R. R., Augustin, N. , Frische, M., Haase, K. M., Basaham, A. and Snow, J. E. (2017) Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions. Contributions to Mineralogy and Petrology, 172 (11-12, Article Nr. 97). DOI 10.1007/s00410-017-1418-1 <https://doi.org/10.1007/s00410-017-1418-1>. doi:10.1007/s00410-017-1418-1 info:eu-repo/semantics/restrictedAccess Article PeerReviewed 2017 ftoceanrep https://doi.org/10.1007/s00410-017-1418-1 2023-04-07T15:36:21Z Hydrothermal circulation at slow-spreading ridges is important for cooling the newly formed lithosphere, but the depth to which it occurs is uncertain. Magmas which stagnate and partially crystallize during their rise from the mantle provide a means to constrain the depth of circulation because assimilation of hydrothermal fluids or hydrothermally altered country rock will raise their chlorine (Cl) contents. Here we present Cl concentrations in combination with chemical thermobarometry data on glassy basaltic rocks and melt inclusions from the Southern Mid-Atlantic Ridge (SMAR; ~ 3 cm year−1 full spreading rate) and the Gakkel Ridge (max. 1.5 cm year−1 full spreading rate) in order to define the depth and extent of chlorine contamination. Basaltic glasses show Cl-contents ranging from ca. 50–430 ppm and ca. 40–700 ppm for the SMAR and Gakkel Ridge, respectively, whereas SMAR melt inclusions contain between 20 and 460 ppm Cl. Compared to elements of similar mantle incompatibility (e.g. K, Nb), Cl-excess (Cl/Nb or Cl/K higher than normal mantle values) of up to 250 ppm in glasses and melt inclusions are found in 75% of the samples from both ridges. Cl-excess is interpreted to indicate assimilation of hydrothermal brines (as opposed to bulk altered rock or seawater) based on the large range of Cl/K ratios in samples showing a limited spread in H2O contents. Resorption and disequilibrium textures of olivine, plagioclase and clinopyroxene phenocrysts and an abundance of xenocrysts and gabbroic fragments in the SMAR lavas suggest multiple generations of crystallization and assimilation of hydrothermally altered rocks that contain these brines. Calculated pressures of last equilibration based on the major element compositions of melts cannot provide reliable estimates of the depths at which this crystallization/assimilation occurred as the assimilation negates the assumption of crystallization under equilibrium conditions implicit in such calculations. Clinopyroxene–melt thermobarometry on rare clinopyroxene ... Article in Journal/Newspaper Arctic Arctic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Arctic Gakkel Ridge ENVELOPE(90.000,90.000,87.000,87.000) Mid-Atlantic Ridge Contributions to Mineralogy and Petrology 172 11-12 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Hydrothermal circulation at slow-spreading ridges is important for cooling the newly formed lithosphere, but the depth to which it occurs is uncertain. Magmas which stagnate and partially crystallize during their rise from the mantle provide a means to constrain the depth of circulation because assimilation of hydrothermal fluids or hydrothermally altered country rock will raise their chlorine (Cl) contents. Here we present Cl concentrations in combination with chemical thermobarometry data on glassy basaltic rocks and melt inclusions from the Southern Mid-Atlantic Ridge (SMAR; ~ 3 cm year−1 full spreading rate) and the Gakkel Ridge (max. 1.5 cm year−1 full spreading rate) in order to define the depth and extent of chlorine contamination. Basaltic glasses show Cl-contents ranging from ca. 50–430 ppm and ca. 40–700 ppm for the SMAR and Gakkel Ridge, respectively, whereas SMAR melt inclusions contain between 20 and 460 ppm Cl. Compared to elements of similar mantle incompatibility (e.g. K, Nb), Cl-excess (Cl/Nb or Cl/K higher than normal mantle values) of up to 250 ppm in glasses and melt inclusions are found in 75% of the samples from both ridges. Cl-excess is interpreted to indicate assimilation of hydrothermal brines (as opposed to bulk altered rock or seawater) based on the large range of Cl/K ratios in samples showing a limited spread in H2O contents. Resorption and disequilibrium textures of olivine, plagioclase and clinopyroxene phenocrysts and an abundance of xenocrysts and gabbroic fragments in the SMAR lavas suggest multiple generations of crystallization and assimilation of hydrothermally altered rocks that contain these brines. Calculated pressures of last equilibration based on the major element compositions of melts cannot provide reliable estimates of the depths at which this crystallization/assimilation occurred as the assimilation negates the assumption of crystallization under equilibrium conditions implicit in such calculations. Clinopyroxene–melt thermobarometry on rare clinopyroxene ... |
format |
Article in Journal/Newspaper |
author |
van der Zwan, Froukje M. Devey, Colin W. Hansteen, Thor H. Almeev, Renat R. Augustin, Nico Frische, Matthias Haase, Karsten M. Basaham, Ali Snow, Jonathan E. |
spellingShingle |
van der Zwan, Froukje M. Devey, Colin W. Hansteen, Thor H. Almeev, Renat R. Augustin, Nico Frische, Matthias Haase, Karsten M. Basaham, Ali Snow, Jonathan E. Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
author_facet |
van der Zwan, Froukje M. Devey, Colin W. Hansteen, Thor H. Almeev, Renat R. Augustin, Nico Frische, Matthias Haase, Karsten M. Basaham, Ali Snow, Jonathan E. |
author_sort |
van der Zwan, Froukje M. |
title |
Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
title_short |
Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
title_full |
Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
title_fullStr |
Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
title_full_unstemmed |
Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions |
title_sort |
lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in arctic and south atlantic basalt glasses and melt inclusions |
publisher |
Springer |
publishDate |
2017 |
url |
https://oceanrep.geomar.de/id/eprint/40109/ https://oceanrep.geomar.de/id/eprint/40109/1/van%20der%20Zwan.pdf https://doi.org/10.1007/s00410-017-1418-1 |
long_lat |
ENVELOPE(90.000,90.000,87.000,87.000) |
geographic |
Arctic Gakkel Ridge Mid-Atlantic Ridge |
geographic_facet |
Arctic Gakkel Ridge Mid-Atlantic Ridge |
genre |
Arctic Arctic |
genre_facet |
Arctic Arctic |
op_relation |
https://oceanrep.geomar.de/id/eprint/40109/1/van%20der%20Zwan.pdf van der Zwan, F. M. , Devey, C. W. , Hansteen, T. H. , Almeev, R. R., Augustin, N. , Frische, M., Haase, K. M., Basaham, A. and Snow, J. E. (2017) Lower crustal hydrothermal circulation at slow-spreading ridges: evidence from chlorine in Arctic and South Atlantic basalt glasses and melt inclusions. Contributions to Mineralogy and Petrology, 172 (11-12, Article Nr. 97). DOI 10.1007/s00410-017-1418-1 <https://doi.org/10.1007/s00410-017-1418-1>. doi:10.1007/s00410-017-1418-1 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1007/s00410-017-1418-1 |
container_title |
Contributions to Mineralogy and Petrology |
container_volume |
172 |
container_issue |
11-12 |
_version_ |
1766301695349882880 |