Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland
The Krafla volcanic system consists of a central volcano and associated fissure swarm in the NE axial rift zone of Iceland. Lavas spanning the whole of Krafla's exposed volcanic history (estimated to be 0-> 300 ka) have been analysed and range in composition from olivine tholeiite to rhyolit...
Published in: | Journal of Petrology |
---|---|
Main Authors: | , , , , , |
Format: | Text |
Language: | English |
Published: |
Oxford University Press
1991
|
Subjects: | |
Online Access: | http://petrology.oxfordjournals.org/cgi/content/short/32/5/1005 https://doi.org/10.1093/petrology/32.5.1005 |
id |
fthighwire:oai:open-archive.highwire.org:petrology:32/5/1005 |
---|---|
record_format |
openpolar |
spelling |
fthighwire:oai:open-archive.highwire.org:petrology:32/5/1005 2023-05-15T16:48:01+02:00 Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland NICHOLSON, HUGH CONDOMINES, MICHEL FITTON, J. GODFREY FALLICK, ANTHONY E. GRÖNVOLD, KARL ROGERS, GRAEME 1991-10-01 00:00:00.0 text/html http://petrology.oxfordjournals.org/cgi/content/short/32/5/1005 https://doi.org/10.1093/petrology/32.5.1005 en eng Oxford University Press http://petrology.oxfordjournals.org/cgi/content/short/32/5/1005 http://dx.doi.org/10.1093/petrology/32.5.1005 Copyright (C) 1991, Oxford University Press Articles TEXT 1991 fthighwire https://doi.org/10.1093/petrology/32.5.1005 2013-05-27T05:02:42Z The Krafla volcanic system consists of a central volcano and associated fissure swarm in the NE axial rift zone of Iceland. Lavas spanning the whole of Krafla's exposed volcanic history (estimated to be 0-> 300 ka) have been analysed and range in composition from olivine tholeiite to rhyolite. Major-element compositions suggest that fractional crystallization exerts the main control over the differentiation process. However, K 2 O and the very incompatible trace elements, Rb, Th, and U, are all enriched beyond the extent expected by closed-system fractional crystallization. Fractionation coupled with periodic replenishment and tapping of the reservoir is unlikely to be responsible for this enrichment, despite the geophysical evidence suggesting a large number of inflations and deflations of a shallow magma reservoir (Tryggvason, 1986). Th- and O-isotope results confirm the work of previous authors that crustal assimilation is operating on a local scale beneath Krafla. A model is suggested, fitting both the Th- and O-isotopic data, which involves the partial melting and incorporation of a hydrothermally altered wall-rock contaminant during fractional crystallization (i. e., AFC processes). This process of partial melting is likely to enhance the most highly incompatible element concentrations (e. g., increasing Rb/Zr) more than expected by closed-system fractional crystallization. Text Iceland HighWire Press (Stanford University) Krafla ENVELOPE(-16.747,-16.747,65.713,65.713) Journal of Petrology 32 5 1005 1020 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Articles |
spellingShingle |
Articles NICHOLSON, HUGH CONDOMINES, MICHEL FITTON, J. GODFREY FALLICK, ANTHONY E. GRÖNVOLD, KARL ROGERS, GRAEME Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
topic_facet |
Articles |
description |
The Krafla volcanic system consists of a central volcano and associated fissure swarm in the NE axial rift zone of Iceland. Lavas spanning the whole of Krafla's exposed volcanic history (estimated to be 0-> 300 ka) have been analysed and range in composition from olivine tholeiite to rhyolite. Major-element compositions suggest that fractional crystallization exerts the main control over the differentiation process. However, K 2 O and the very incompatible trace elements, Rb, Th, and U, are all enriched beyond the extent expected by closed-system fractional crystallization. Fractionation coupled with periodic replenishment and tapping of the reservoir is unlikely to be responsible for this enrichment, despite the geophysical evidence suggesting a large number of inflations and deflations of a shallow magma reservoir (Tryggvason, 1986). Th- and O-isotope results confirm the work of previous authors that crustal assimilation is operating on a local scale beneath Krafla. A model is suggested, fitting both the Th- and O-isotopic data, which involves the partial melting and incorporation of a hydrothermally altered wall-rock contaminant during fractional crystallization (i. e., AFC processes). This process of partial melting is likely to enhance the most highly incompatible element concentrations (e. g., increasing Rb/Zr) more than expected by closed-system fractional crystallization. |
format |
Text |
author |
NICHOLSON, HUGH CONDOMINES, MICHEL FITTON, J. GODFREY FALLICK, ANTHONY E. GRÖNVOLD, KARL ROGERS, GRAEME |
author_facet |
NICHOLSON, HUGH CONDOMINES, MICHEL FITTON, J. GODFREY FALLICK, ANTHONY E. GRÖNVOLD, KARL ROGERS, GRAEME |
author_sort |
NICHOLSON, HUGH |
title |
Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
title_short |
Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
title_full |
Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
title_fullStr |
Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
title_full_unstemmed |
Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland |
title_sort |
geochemical and isotopic evidence for crustal assimilation beneath krafla, iceland |
publisher |
Oxford University Press |
publishDate |
1991 |
url |
http://petrology.oxfordjournals.org/cgi/content/short/32/5/1005 https://doi.org/10.1093/petrology/32.5.1005 |
long_lat |
ENVELOPE(-16.747,-16.747,65.713,65.713) |
geographic |
Krafla |
geographic_facet |
Krafla |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
http://petrology.oxfordjournals.org/cgi/content/short/32/5/1005 http://dx.doi.org/10.1093/petrology/32.5.1005 |
op_rights |
Copyright (C) 1991, Oxford University Press |
op_doi |
https://doi.org/10.1093/petrology/32.5.1005 |
container_title |
Journal of Petrology |
container_volume |
32 |
container_issue |
5 |
container_start_page |
1005 |
op_container_end_page |
1020 |
_version_ |
1766038109924884480 |