Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system

The 1783–1784 AD fissure eruption of Laki (Iceland) produced 15 km^3 of homogeneous basaltic lavas and tephra that are characterized by extreme (3‰) ^(18)O-depletion relative to normal mantle. Basaltic tephra erupted over the last 8 centuries and as late as in November 2004 from the Grímsvötn centra...

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Published in:Earth and Planetary Science Letters
Main Authors: Bindeman, Ilya N., Sigmarsson, Olgeir, Eiler, John
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2006
Subjects:
Online Access:https://authors.library.caltech.edu/35170/
https://authors.library.caltech.edu/35170/2/mmc1.pdf
https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136
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spelling ftcaltechauth:oai:authors.library.caltech.edu:35170 2023-05-15T16:52:59+02:00 Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system Bindeman, Ilya N. Sigmarsson, Olgeir Eiler, John 2006-05-15 application/pdf https://authors.library.caltech.edu/35170/ https://authors.library.caltech.edu/35170/2/mmc1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136 en eng Elsevier https://authors.library.caltech.edu/35170/2/mmc1.pdf Bindeman, Ilya N. and Sigmarsson, Olgeir and Eiler, John (2006) Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system. Earth and Planetary Science Letters, 245 (1-2). pp. 245-259. ISSN 0012-821X. doi:10.1016/j.epsl.2006.02.029. https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136 <https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136> other Article PeerReviewed 2006 ftcaltechauth https://doi.org/10.1016/j.epsl.2006.02.029 2021-11-11T18:51:45Z The 1783–1784 AD fissure eruption of Laki (Iceland) produced 15 km^3 of homogeneous basaltic lavas and tephra that are characterized by extreme (3‰) ^(18)O-depletion relative to normal mantle. Basaltic tephra erupted over the last 8 centuries and as late as in November 2004 from the Grímsvötn central volcano, which together with Laki are a part of a single volcanic system, is indistinguishable in δ^(18)O from Laki glass. This suggests that all tap a homogeneous and long-lived low-δ^(18)O magma reservoir. In contrast, we observe extreme oxygen isotope heterogeneity (2.2–5.2‰) in olivine and plagioclase contained within these lavas and tephra, and disequilibrium mineral-glass oxygen-isotope fractionations. Such low-δ^(18)O_(glass) values, and extreme 3‰ range in δ^(18)O_(olivine) have not been described in any other unaltered basalt. The energy constrained mass balance calculation involving oxygen isotopes and major element composition calls for an origin of the Laki–Grímsvötn quartz tholeiitic basaltic melts with δ^(18)O = 3.1‰ by bulk digestion of low-δ^(18)O hydrated basaltic crust with δ^(18)O = − 4‰ to + 1‰, rather than magma mixing with ultra-low-δ^(18)O silicic melt. The abundant Pleistocene hyaloclastites, which were altered by synglacial meltwaters, can serve as a likely assimilant material for the Grímsvötn magmas. The (^(226)Ra /^(230)Th) activity ratio in Laki lavas and 20th century Grímsvötn tephras is 13% in-excess of secular equilibrium, but products of the 20th century Grímsvötn eruptions have equilibrium (^(210)Pb /^(226)Ra). Modeling of oxygen isotope exchange between disequilibrium phenocrysts and magmas, and these short-lived U-series nuclides yields a coherent age for the Laki–Grímsvötn magma reservoir between 100 and 1000 yrs. We propose the existence of uniquely fingerprinted, low-δ^(18)O, homogeneous, large volume, and long-lived basaltic reservoir beneath the Laki–Grímsvötn volcanic system that has been kept alive in its position above the center of the Icelandic mantle plume. Melt generation, crustal assimilation, magma storage and homogenization all took place in only a few thousands of years at most. Article in Journal/Newspaper Iceland Caltech Authors (California Institute of Technology) Laki ENVELOPE(-18.237,-18.237,64.070,64.070) Earth and Planetary Science Letters 245 1-2 245 259
institution Open Polar
collection Caltech Authors (California Institute of Technology)
op_collection_id ftcaltechauth
language English
description The 1783–1784 AD fissure eruption of Laki (Iceland) produced 15 km^3 of homogeneous basaltic lavas and tephra that are characterized by extreme (3‰) ^(18)O-depletion relative to normal mantle. Basaltic tephra erupted over the last 8 centuries and as late as in November 2004 from the Grímsvötn central volcano, which together with Laki are a part of a single volcanic system, is indistinguishable in δ^(18)O from Laki glass. This suggests that all tap a homogeneous and long-lived low-δ^(18)O magma reservoir. In contrast, we observe extreme oxygen isotope heterogeneity (2.2–5.2‰) in olivine and plagioclase contained within these lavas and tephra, and disequilibrium mineral-glass oxygen-isotope fractionations. Such low-δ^(18)O_(glass) values, and extreme 3‰ range in δ^(18)O_(olivine) have not been described in any other unaltered basalt. The energy constrained mass balance calculation involving oxygen isotopes and major element composition calls for an origin of the Laki–Grímsvötn quartz tholeiitic basaltic melts with δ^(18)O = 3.1‰ by bulk digestion of low-δ^(18)O hydrated basaltic crust with δ^(18)O = − 4‰ to + 1‰, rather than magma mixing with ultra-low-δ^(18)O silicic melt. The abundant Pleistocene hyaloclastites, which were altered by synglacial meltwaters, can serve as a likely assimilant material for the Grímsvötn magmas. The (^(226)Ra /^(230)Th) activity ratio in Laki lavas and 20th century Grímsvötn tephras is 13% in-excess of secular equilibrium, but products of the 20th century Grímsvötn eruptions have equilibrium (^(210)Pb /^(226)Ra). Modeling of oxygen isotope exchange between disequilibrium phenocrysts and magmas, and these short-lived U-series nuclides yields a coherent age for the Laki–Grímsvötn magma reservoir between 100 and 1000 yrs. We propose the existence of uniquely fingerprinted, low-δ^(18)O, homogeneous, large volume, and long-lived basaltic reservoir beneath the Laki–Grímsvötn volcanic system that has been kept alive in its position above the center of the Icelandic mantle plume. Melt generation, crustal assimilation, magma storage and homogenization all took place in only a few thousands of years at most.
format Article in Journal/Newspaper
author Bindeman, Ilya N.
Sigmarsson, Olgeir
Eiler, John
spellingShingle Bindeman, Ilya N.
Sigmarsson, Olgeir
Eiler, John
Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
author_facet Bindeman, Ilya N.
Sigmarsson, Olgeir
Eiler, John
author_sort Bindeman, Ilya N.
title Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
title_short Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
title_full Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
title_fullStr Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
title_full_unstemmed Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system
title_sort time constraints on the origin of large volume basalts derived from o-isotope and trace element mineral zoning and u-series disequilibria in the laki and grímsvötn volcanic system
publisher Elsevier
publishDate 2006
url https://authors.library.caltech.edu/35170/
https://authors.library.caltech.edu/35170/2/mmc1.pdf
https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136
long_lat ENVELOPE(-18.237,-18.237,64.070,64.070)
geographic Laki
geographic_facet Laki
genre Iceland
genre_facet Iceland
op_relation https://authors.library.caltech.edu/35170/2/mmc1.pdf
Bindeman, Ilya N. and Sigmarsson, Olgeir and Eiler, John (2006) Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grímsvötn volcanic system. Earth and Planetary Science Letters, 245 (1-2). pp. 245-259. ISSN 0012-821X. doi:10.1016/j.epsl.2006.02.029. https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136 <https://resolver.caltech.edu/CaltechAUTHORS:20121030-092945136>
op_rights other
op_doi https://doi.org/10.1016/j.epsl.2006.02.029
container_title Earth and Planetary Science Letters
container_volume 245
container_issue 1-2
container_start_page 245
op_container_end_page 259
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