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Sökning: WFRF:(Stefansson K.) > Naturhistoriska riksmuseet

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  • Jackson, Marie, et al. (författare)
  • Time-lapse characterization of hydrothermal seawater and microbial interactions with basaltic tephra at Surtsey volcano
  • 2015
  • Ingår i: Scientific Drilling. - Copernicus Publications on behalf of the IODP and the ICDP : Copernicus GmbH. - 1816-8957 .- 1816-3459. ; 20, s. 51-58
  • Tidskriftsartikel (refereegranskat)abstract
    • A new International Continental Drilling Program (ICDP) project will drill through the 50-yearold edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963–1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions.
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3.
  • Kleine, B. I., et al. (författare)
  • Silicon and oxygen isotopes unravel quartz formation processes in the Icelandic crust
  • 2018
  • Ingår i: Geochemical Perspectives Letters. ; 7, s. 5-11
  • Tidskriftsartikel (refereegranskat)abstract
    • Quartz formation processes in the Icelandic crust were assessed using coupled δ18O and δ30Si systematics of silica deposits formed over a wide temperature range (<150 to >550 °C). Magmatic quartz reveals δ18O (-5.6 to +6.6 ‰) and δ30Si (-0.4 ± 0.2 ‰) values representative of mantle- and crustally-derived melts in Iceland. Hydrothermal quartz and silica polymorphs display a larger range of δ18O (-9.3 to +30.1 ‰) and δ30Si (-4.6 to +0.7 ‰) values. Isotope modelling reveals that such large variations are consistent with variable water sources and equilibrium isotope fractionation between fluids and quartz associated with secondary processes occurring in the crust, including fluid-rock interaction, boiling and cooling. In context of published δ18O and δ30Si data on hydrothermal silica deposits, we demonstrate that large ranges in δ30Si values coupled to insignificant δ18O variations may result from silica precipitation in a hydrothermal fluid conduit associated with near-surface cooling. While equilibrium isotope fractionation between fluids and quartz seems to prevail at high temperatures, kinetic fractionation likely influences isotope systematics at low temperatures.
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