To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths
International audience We have studied glass-bearing leucocratic (granitic to Qz-monzonitic) crustal xenoliths from the Tindfjöll Pleistocene volcanic complex, SW Iceland. The xenoliths consist of strongly resorbed relicts of anorthitic plagioclase, K-rich feldspar and rounded quartz in colorless th...
Published in: | Contributions to Mineralogy and Petrology |
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Online Access: | https://hal.univ-lorraine.fr/hal-01771549 https://doi.org/10.1007/s00410-015-1145-4 |
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ftunilorrainehal:oai:HAL:hal-01771549v1 2023-10-09T21:52:43+02:00 To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths Gurenko, Andrey Bindeman, Ilya Sigurdsson, Ingvar Centre de Recherches Pétrographiques et Géochimiques (CRPG) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) Woods Hole Oceanographic Institution (WHOI) Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft Department of Geological Sciences Oregon University of Oregon Eugene Southwest Iceland Nature Research Centre 2015-05 https://hal.univ-lorraine.fr/hal-01771549 https://doi.org/10.1007/s00410-015-1145-4 en eng HAL CCSD Springer Verlag info:eu-repo/semantics/altIdentifier/doi/10.1007/s00410-015-1145-4 hal-01771549 https://hal.univ-lorraine.fr/hal-01771549 doi:10.1007/s00410-015-1145-4 ISSN: 0010-7999 EISSN: 1432-0967 Contributions to Mineralogy and Petrology https://hal.univ-lorraine.fr/hal-01771549 Contributions to Mineralogy and Petrology, 2015, 169 (5), ⟨10.1007/s00410-015-1145-4⟩ Iceland Rhyolites Leucocratic xenoliths Oxygen isotopes Zircon age [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2015 ftunilorrainehal https://doi.org/10.1007/s00410-015-1145-4 2023-09-12T23:20:38Z International audience We have studied glass-bearing leucocratic (granitic to Qz-monzonitic) crustal xenoliths from the Tindfjöll Pleistocene volcanic complex, SW Iceland. The xenoliths consist of strongly resorbed relicts of anorthitic plagioclase, K-rich feldspar and rounded quartz in colorless through pale to dark-brown interstitial glass. Spongy clinopyroxene and/or rounded or elongated crystals of orthopyroxene are in subordinate amount. Magnetite, ilmenite, zircon, apatite, allanite and/or chevkinite are accessory minerals. The xenoliths more likely are relicts of earlier-formed, partially melted Si-rich rocks or quartz–feldspar-rich crystal segregations, which suffered latter interaction with hotter and more primitive magma(s). Icelandic lavas are typically low in δ 18O compared to mantle-derived, “MORB”-like rocks (~5.6 ± 0.2 ‰), likely due to their interaction with, or contamination by, the upper-crustal rocks affected by rain and glacial melt waters. Surprisingly, many quartz and feldspar crystals and associated colorless to light-colored interstitial glasses of the studied xenoliths are not low but high in δ 18O (5.1–7.2 ‰, excluding three dark-brown glasses of 4–5 ‰). The xenoliths contain abundant, low- to high-δ 18O (2.4–6.3 ‰) young zircons (U–Pb age 0.2–0.27 ± 0.03 Ma; U–Th age 0.16 ± 0.07 Ma), most of them in oxygen isotope equilibrium with interstitial glasses. The δ 18O values >5.6 ‰ recorded in the coexisting zircon, quartz, feldspar and colorless interstitial glass suggest crystallization from melts produced by fusion of crustal rocks altered by seawater, also reflecting multiple melting and crystallization events. This suggests that “normal”-δ 18O silicic magmas may not be ultimately produced by crystallization of mafic, basaltic magmas. Instead, our new single-crystal laser fluorination and ion microprobe O-isotope data suggest addition of diverse partial crustal melts, probably originated from variously altered and preconditioned crust. Article in Journal/Newspaper Iceland Université de Lorraine: HAL Contributions to Mineralogy and Petrology 169 5 |
institution |
Open Polar |
collection |
Université de Lorraine: HAL |
op_collection_id |
ftunilorrainehal |
language |
English |
topic |
Iceland Rhyolites Leucocratic xenoliths Oxygen isotopes Zircon age [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Iceland Rhyolites Leucocratic xenoliths Oxygen isotopes Zircon age [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Gurenko, Andrey Bindeman, Ilya Sigurdsson, Ingvar To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
topic_facet |
Iceland Rhyolites Leucocratic xenoliths Oxygen isotopes Zircon age [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience We have studied glass-bearing leucocratic (granitic to Qz-monzonitic) crustal xenoliths from the Tindfjöll Pleistocene volcanic complex, SW Iceland. The xenoliths consist of strongly resorbed relicts of anorthitic plagioclase, K-rich feldspar and rounded quartz in colorless through pale to dark-brown interstitial glass. Spongy clinopyroxene and/or rounded or elongated crystals of orthopyroxene are in subordinate amount. Magnetite, ilmenite, zircon, apatite, allanite and/or chevkinite are accessory minerals. The xenoliths more likely are relicts of earlier-formed, partially melted Si-rich rocks or quartz–feldspar-rich crystal segregations, which suffered latter interaction with hotter and more primitive magma(s). Icelandic lavas are typically low in δ 18O compared to mantle-derived, “MORB”-like rocks (~5.6 ± 0.2 ‰), likely due to their interaction with, or contamination by, the upper-crustal rocks affected by rain and glacial melt waters. Surprisingly, many quartz and feldspar crystals and associated colorless to light-colored interstitial glasses of the studied xenoliths are not low but high in δ 18O (5.1–7.2 ‰, excluding three dark-brown glasses of 4–5 ‰). The xenoliths contain abundant, low- to high-δ 18O (2.4–6.3 ‰) young zircons (U–Pb age 0.2–0.27 ± 0.03 Ma; U–Th age 0.16 ± 0.07 Ma), most of them in oxygen isotope equilibrium with interstitial glasses. The δ 18O values >5.6 ‰ recorded in the coexisting zircon, quartz, feldspar and colorless interstitial glass suggest crystallization from melts produced by fusion of crustal rocks altered by seawater, also reflecting multiple melting and crystallization events. This suggests that “normal”-δ 18O silicic magmas may not be ultimately produced by crystallization of mafic, basaltic magmas. Instead, our new single-crystal laser fluorination and ion microprobe O-isotope data suggest addition of diverse partial crustal melts, probably originated from variously altered and preconditioned crust. |
author2 |
Centre de Recherches Pétrographiques et Géochimiques (CRPG) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) Woods Hole Oceanographic Institution (WHOI) Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft Department of Geological Sciences Oregon University of Oregon Eugene Southwest Iceland Nature Research Centre |
format |
Article in Journal/Newspaper |
author |
Gurenko, Andrey Bindeman, Ilya Sigurdsson, Ingvar |
author_facet |
Gurenko, Andrey Bindeman, Ilya Sigurdsson, Ingvar |
author_sort |
Gurenko, Andrey |
title |
To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
title_short |
To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
title_full |
To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
title_fullStr |
To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
title_full_unstemmed |
To the origin of Icelandic rhyolites: insights from partially melted leucocratic xenoliths |
title_sort |
to the origin of icelandic rhyolites: insights from partially melted leucocratic xenoliths |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal.univ-lorraine.fr/hal-01771549 https://doi.org/10.1007/s00410-015-1145-4 |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
ISSN: 0010-7999 EISSN: 1432-0967 Contributions to Mineralogy and Petrology https://hal.univ-lorraine.fr/hal-01771549 Contributions to Mineralogy and Petrology, 2015, 169 (5), ⟨10.1007/s00410-015-1145-4⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/s00410-015-1145-4 hal-01771549 https://hal.univ-lorraine.fr/hal-01771549 doi:10.1007/s00410-015-1145-4 |
op_doi |
https://doi.org/10.1007/s00410-015-1145-4 |
container_title |
Contributions to Mineralogy and Petrology |
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169 |
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5 |
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