Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland
Iceland straddles the mid-Atlantic spreading axis, between the Kolbeinsey Ridge to the north and the Reykjanes Ridge to the south. Published geochemical data from the Reykjanes Ridge show evidence for mixing between a MORB component and the Iceland plume. Available data from the Kolbeinsey Ridge sug...
Published in: | Earth and Planetary Science Letters |
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Elsevier
1991
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ftoceanrep:oai:oceanrep.geomar.de:6305 2023-05-15T13:41:29+02:00 Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland Mertz, D.F. Devey, Colin W. Todt, W. Stoffers, Peter Hofmann, A.W. 1991 text https://oceanrep.geomar.de/id/eprint/6305/ https://oceanrep.geomar.de/id/eprint/6305/1/1-s2.0-0012821X9190074R-main.pdf https://doi.org/10.1016/0012-821X(91)90074-R en eng Elsevier https://oceanrep.geomar.de/id/eprint/6305/1/1-s2.0-0012821X9190074R-main.pdf Mertz, D. F., Devey, C. W. , Todt, W., Stoffers, P. and Hofmann, A. W. (1991) Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland. Earth and Planetary Science Letters, 107 (2). pp. 243-255. DOI 10.1016/0012-821X(91)90074-R <https://doi.org/10.1016/0012-821X%2891%2990074-R>. doi:10.1016/0012-821X(91)90074-R info:eu-repo/semantics/restrictedAccess Article PeerReviewed 1991 ftoceanrep https://doi.org/10.1016/0012-821X(91)90074-R 2023-04-07T14:52:35Z Iceland straddles the mid-Atlantic spreading axis, between the Kolbeinsey Ridge to the north and the Reykjanes Ridge to the south. Published geochemical data from the Reykjanes Ridge show evidence for mixing between a MORB component and the Iceland plume. Available data from the Kolbeinsey Ridge suggest that similar mixing may not be occurring there. To investigate in detail the relationship between the Iceland plume and MORB along the Kolbeinsey Ridge, we have collected and analysed samples between the Tjo¨rnes and Spar fracture zones (ca. 67°–69°N). The 16 Kolbeinsey Ridge samples show limited isotopic variation and are characterised by relatively unradiogenic Pb (206Pb/204Pb= 17.912 to 18.053, 207Pb/204Pb= 15.404 to 15.453 and 208Pb/204Pb= 37.543 to 37.690, 87Sr/86Sr= 0.70280 to 0.70298, 143Nd/144Nd= 0.51307 to 0.51323). On the basis of their Rb, Sr, Nd, Sm, U, Th and Pb concentrations, the basalts are N-type MORB. Sr and Nd isotope ratios show significant systematic variations with latitude, becoming more enriched (87Sr/86Sr increases, 143Nd/144Nd decreases) towards Iceland, apparently supporting the classical model of plume-asthenosphere mixing. However, the Pb isotopes show no such relationship, and are thus inconsistent with this mixing model. On the basis of Pb and Sr isotope data it is possible to exclude the Iceland source as an end-member in the genesis of the Kolbeinsey Ridge basalts, implying that Iceland plume material does not flow northward along the Kolbeinsey Ridge. The isotopic variations within the Kolbeinsey data set can be attributed to heterogeneities in the MORB source. The boundary between the plume and MORB sources appears to coincide with the Tjo¨rnes Fracture Zone. This fracture zone may, by analogy with the Australia-Antarctic Discordance, overlie a zone of mantle convergence. The topographic anomalies over the Kolbeinsey and Reykjanes Ridges imply that hot, less dense material underlies them both. The absence of an Icelandic plume signature in the Kolbeinsey geochemistry, however, ... Article in Journal/Newspaper Antarc* Antarctic Iceland Kolbeinsey OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Antarctic Kolbeinsey ENVELOPE(-18.687,-18.687,67.149,67.149) Kolbeinsey Ridge ENVELOPE(-16.917,-16.917,68.833,68.833) Reykjanes ENVELOPE(-22.250,-22.250,65.467,65.467) Earth and Planetary Science Letters 107 2 243 255 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Iceland straddles the mid-Atlantic spreading axis, between the Kolbeinsey Ridge to the north and the Reykjanes Ridge to the south. Published geochemical data from the Reykjanes Ridge show evidence for mixing between a MORB component and the Iceland plume. Available data from the Kolbeinsey Ridge suggest that similar mixing may not be occurring there. To investigate in detail the relationship between the Iceland plume and MORB along the Kolbeinsey Ridge, we have collected and analysed samples between the Tjo¨rnes and Spar fracture zones (ca. 67°–69°N). The 16 Kolbeinsey Ridge samples show limited isotopic variation and are characterised by relatively unradiogenic Pb (206Pb/204Pb= 17.912 to 18.053, 207Pb/204Pb= 15.404 to 15.453 and 208Pb/204Pb= 37.543 to 37.690, 87Sr/86Sr= 0.70280 to 0.70298, 143Nd/144Nd= 0.51307 to 0.51323). On the basis of their Rb, Sr, Nd, Sm, U, Th and Pb concentrations, the basalts are N-type MORB. Sr and Nd isotope ratios show significant systematic variations with latitude, becoming more enriched (87Sr/86Sr increases, 143Nd/144Nd decreases) towards Iceland, apparently supporting the classical model of plume-asthenosphere mixing. However, the Pb isotopes show no such relationship, and are thus inconsistent with this mixing model. On the basis of Pb and Sr isotope data it is possible to exclude the Iceland source as an end-member in the genesis of the Kolbeinsey Ridge basalts, implying that Iceland plume material does not flow northward along the Kolbeinsey Ridge. The isotopic variations within the Kolbeinsey data set can be attributed to heterogeneities in the MORB source. The boundary between the plume and MORB sources appears to coincide with the Tjo¨rnes Fracture Zone. This fracture zone may, by analogy with the Australia-Antarctic Discordance, overlie a zone of mantle convergence. The topographic anomalies over the Kolbeinsey and Reykjanes Ridges imply that hot, less dense material underlies them both. The absence of an Icelandic plume signature in the Kolbeinsey geochemistry, however, ... |
format |
Article in Journal/Newspaper |
author |
Mertz, D.F. Devey, Colin W. Todt, W. Stoffers, Peter Hofmann, A.W. |
spellingShingle |
Mertz, D.F. Devey, Colin W. Todt, W. Stoffers, Peter Hofmann, A.W. Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
author_facet |
Mertz, D.F. Devey, Colin W. Todt, W. Stoffers, Peter Hofmann, A.W. |
author_sort |
Mertz, D.F. |
title |
Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
title_short |
Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
title_full |
Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
title_fullStr |
Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
title_full_unstemmed |
Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland |
title_sort |
sr-nd-pb isotope evidence against plume-asthenosphere mixing north of iceland |
publisher |
Elsevier |
publishDate |
1991 |
url |
https://oceanrep.geomar.de/id/eprint/6305/ https://oceanrep.geomar.de/id/eprint/6305/1/1-s2.0-0012821X9190074R-main.pdf https://doi.org/10.1016/0012-821X(91)90074-R |
long_lat |
ENVELOPE(-18.687,-18.687,67.149,67.149) ENVELOPE(-16.917,-16.917,68.833,68.833) ENVELOPE(-22.250,-22.250,65.467,65.467) |
geographic |
Antarctic Kolbeinsey Kolbeinsey Ridge Reykjanes |
geographic_facet |
Antarctic Kolbeinsey Kolbeinsey Ridge Reykjanes |
genre |
Antarc* Antarctic Iceland Kolbeinsey |
genre_facet |
Antarc* Antarctic Iceland Kolbeinsey |
op_relation |
https://oceanrep.geomar.de/id/eprint/6305/1/1-s2.0-0012821X9190074R-main.pdf Mertz, D. F., Devey, C. W. , Todt, W., Stoffers, P. and Hofmann, A. W. (1991) Sr-Nd-Pb isotope evidence against plume-asthenosphere mixing north of Iceland. Earth and Planetary Science Letters, 107 (2). pp. 243-255. DOI 10.1016/0012-821X(91)90074-R <https://doi.org/10.1016/0012-821X%2891%2990074-R>. doi:10.1016/0012-821X(91)90074-R |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/0012-821X(91)90074-R |
container_title |
Earth and Planetary Science Letters |
container_volume |
107 |
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2 |
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243 |
op_container_end_page |
255 |
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1766151418344898560 |