Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean)
Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been significantly less studied than those from other oceans. The Arctic ridges (Gakkel Ridge and Lena Trough) are ultraslow-spreading ridges with low melt productivity and are thus the best locations to investigate mantle heterogeneity. We r...
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fthighwire:oai:open-archive.highwire.org:petrology:52/6/1185 2023-05-15T14:54:31+02:00 Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) Nauret, F. Snow, J. E. Hellebrand, E. Weis, D. 2011-06-01 00:00:00.0 text/html http://petrology.oxfordjournals.org/cgi/content/short/52/6/1185 https://doi.org/10.1093/petrology/egr024 en eng Oxford University Press http://petrology.oxfordjournals.org/cgi/content/short/52/6/1185 http://dx.doi.org/10.1093/petrology/egr024 Copyright (C) 2011, Oxford University Press Original Papers TEXT 2011 fthighwire https://doi.org/10.1093/petrology/egr024 2013-05-28T09:46:37Z Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been significantly less studied than those from other oceans. The Arctic ridges (Gakkel Ridge and Lena Trough) are ultraslow-spreading ridges with low melt productivity and are thus the best locations to investigate mantle heterogeneity. We report the major and trace element and Sr–Nd–Pb–Hf isotope compositions of basalts generated along the Lena Trough and the westernmost part of the Gakkel Ridge in the Arctic Ocean. Basalts from the northern Lena Trough and westernmost Gakkel Ridge (NLT–WGR) have compositions close to normal MORB. The geochemical composition of the NLT–WGR lavas confirms a binary mixing model involving melts from a depleted MORB mantle source and a Spitsbergen amphibole-bearing subcontinental lithospheric mantle (SCLM) source. In contrast, in the central part of the Lena Trough (CLT), the basalts are alkalic with relatively high Mg-number (60–65), high SiO 2 (51·0–51·6 wt %), Al 2 O 3 (18·1–18·4 wt %), Na 2 O (4·0–4·2 wt %), K 2 O (1·0–1·6 wt %), K 2 O/TiO 2 (0·6–0·9) and (La/Sm) PM (1·4–1·8), and low FeO (6·5–6·8 wt %) contents. These basalts display isotope variations with 87Sr/86Sr ranging from 0·70361 to 0·70390, 143Nd/144Nd from 0·51283 to 0·51290 (ε Nd + 3·7 to +5·2), 176Hf/177Hf from 0·28313 to 0·28322 (ε Hf + 11·6 to +14·9) and 206Pb/204Pb from 17·752 to 17·884, 207Pb/204Pb from 15·410 to 15·423 and 208Pb/204Pb from 37·544 to 37·670. These isotope compositions clearly distinguish the CLT lavas from those generated along the Gakkel Ridge. For the CLT lavas, involvement of a phlogopite- or amphibole- and (possibly garnet)-bearing SCLM source component is proposed. Owing to SCLM contamination along the entire length of the Lena Trough, we classify the Lena Trough as an ocean–continent transition boundary. Magmatism similar to that observed in the Lena Trough would be expected to occur wherever ocean spreading initiates. Text Arctic Arctic Ocean Spitsbergen HighWire Press (Stanford University) Arctic Arctic Ocean Gakkel Ridge ENVELOPE(90.000,90.000,87.000,87.000) Journal of Petrology 52 6 1185 1206 |
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English |
topic |
Original Papers |
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Original Papers Nauret, F. Snow, J. E. Hellebrand, E. Weis, D. Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
topic_facet |
Original Papers |
description |
Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been significantly less studied than those from other oceans. The Arctic ridges (Gakkel Ridge and Lena Trough) are ultraslow-spreading ridges with low melt productivity and are thus the best locations to investigate mantle heterogeneity. We report the major and trace element and Sr–Nd–Pb–Hf isotope compositions of basalts generated along the Lena Trough and the westernmost part of the Gakkel Ridge in the Arctic Ocean. Basalts from the northern Lena Trough and westernmost Gakkel Ridge (NLT–WGR) have compositions close to normal MORB. The geochemical composition of the NLT–WGR lavas confirms a binary mixing model involving melts from a depleted MORB mantle source and a Spitsbergen amphibole-bearing subcontinental lithospheric mantle (SCLM) source. In contrast, in the central part of the Lena Trough (CLT), the basalts are alkalic with relatively high Mg-number (60–65), high SiO 2 (51·0–51·6 wt %), Al 2 O 3 (18·1–18·4 wt %), Na 2 O (4·0–4·2 wt %), K 2 O (1·0–1·6 wt %), K 2 O/TiO 2 (0·6–0·9) and (La/Sm) PM (1·4–1·8), and low FeO (6·5–6·8 wt %) contents. These basalts display isotope variations with 87Sr/86Sr ranging from 0·70361 to 0·70390, 143Nd/144Nd from 0·51283 to 0·51290 (ε Nd + 3·7 to +5·2), 176Hf/177Hf from 0·28313 to 0·28322 (ε Hf + 11·6 to +14·9) and 206Pb/204Pb from 17·752 to 17·884, 207Pb/204Pb from 15·410 to 15·423 and 208Pb/204Pb from 37·544 to 37·670. These isotope compositions clearly distinguish the CLT lavas from those generated along the Gakkel Ridge. For the CLT lavas, involvement of a phlogopite- or amphibole- and (possibly garnet)-bearing SCLM source component is proposed. Owing to SCLM contamination along the entire length of the Lena Trough, we classify the Lena Trough as an ocean–continent transition boundary. Magmatism similar to that observed in the Lena Trough would be expected to occur wherever ocean spreading initiates. |
format |
Text |
author |
Nauret, F. Snow, J. E. Hellebrand, E. Weis, D. |
author_facet |
Nauret, F. Snow, J. E. Hellebrand, E. Weis, D. |
author_sort |
Nauret, F. |
title |
Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
title_short |
Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
title_full |
Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
title_fullStr |
Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
title_full_unstemmed |
Geochemical Composition of K-rich Lavas from the Lena Trough (Arctic Ocean) |
title_sort |
geochemical composition of k-rich lavas from the lena trough (arctic ocean) |
publisher |
Oxford University Press |
publishDate |
2011 |
url |
http://petrology.oxfordjournals.org/cgi/content/short/52/6/1185 https://doi.org/10.1093/petrology/egr024 |
long_lat |
ENVELOPE(90.000,90.000,87.000,87.000) |
geographic |
Arctic Arctic Ocean Gakkel Ridge |
geographic_facet |
Arctic Arctic Ocean Gakkel Ridge |
genre |
Arctic Arctic Ocean Spitsbergen |
genre_facet |
Arctic Arctic Ocean Spitsbergen |
op_relation |
http://petrology.oxfordjournals.org/cgi/content/short/52/6/1185 http://dx.doi.org/10.1093/petrology/egr024 |
op_rights |
Copyright (C) 2011, Oxford University Press |
op_doi |
https://doi.org/10.1093/petrology/egr024 |
container_title |
Journal of Petrology |
container_volume |
52 |
container_issue |
6 |
container_start_page |
1185 |
op_container_end_page |
1206 |
_version_ |
1766326226637553664 |