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  • 1.
    Andrén, Margareta
    et al.
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Stockmann, Gabrielle
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Skelton, Alasdair
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Sturkell, Erik
    Univ Gothenburg, Dept Earth Sci, Gothenburg, Sweden.
    Mörth, Carl-Magnus
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Guðrúnardóttir, Helga Rakel
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Keller, Nicole Simone
    Univ Iceland, Inst Earth Sci, Reykjavik, Iceland.
    Odling, Nic
    Univ Edinburgh, Sch Geosci, Edinburgh, Midlothian, Scotland.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Broman, Curt
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Balic-Zunic, Tonci
    Univ Copenhagen, Nat Hist Museum, Copenhagen, Denmark.
    Hjartarsson, Hreinn
    Landsvirkjun, Reykjavik, Iceland.
    Siegmund, Heike
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Freund, Friedemann
    NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA.
    Kockum, Ingrid
    NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA.
    Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland2016In: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 121, no 4, p. 2315-2337Article in journal (Refereed)
    Abstract [en]

    Chemical analysis of groundwater samples collected from a borehole at Hafralækur, northernIceland, from October 2008 to June 2015 revealed (1) a long-term decrease in concentration of Si and Naand (2) an abrupt increase in concentration of Na before each of two consecutive M > 5 earthquakes whichoccurred in 2012 and 2013, both 76 km from Hafralækur. Based on a geochemical (major elements and stableisotopes), petrological, and mineralogical study of drill cuttings taken from an adjacent borehole, we areable to show that (1) the long-term decrease in concentration of Si and Na was caused by constant volumereplacement of labradorite by analcime coupled with precipitation of zeolites in vesicles and along fracturesand (2) the abrupt increase of Na concentration before the first earthquake records a switchover tononstoichiometric dissolution of analcime with preferential release of Na into groundwater. We attributedecay of the Na peaks, which followed and coincided with each earthquake to uptake of Na along fracturedor porous boundaries between labradorite and analcime crystals. Possible causes of these Na peaks are anincrease of reactive surface area caused by fracturing or a shift from chemical equilibrium caused by mixingbetween groundwater components. Both could have been triggered by preseismic dilation, which was alsoinferred in a previous study by Skelton et al. (2014). The mechanism behind preseismic dilation so far from thefocus of an earthquake remains unknown.

  • 2.
    Budd, David A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Dahren, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Persistent multitiered magma plumbing beneath Katla volcano, Iceland2016In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 17, no 3, p. 966-980Article in journal (Refereed)
    Abstract [en]

    Recent seismic unrest and a persistent Holocene eruption record at Katla volcano, Iceland indicate that a near-future eruption is possible. Previous petrological investigations suggest that Katla is supplied by a simple plumbing system that delivers magma directly from depth, while seismic and geodetic data also point toward the existence of upper-crustal magma storage. To characterize Katla's recent plumbing system, we established mineral-melt equilibrium crystallization pressures from four age-constrained Katla tephras spanning from 8 kyr BP to 1918. The results point to persistent shallow- (≤8 km depth) as well as deep-crustal (ca. 10 – 25 km depth) magma storage beneath Katla throughout the last 8 kyr. The presence of multiple magma storage regions implies that mafic magma from the deeper reservoir system may become gas-rich during ascent and storage in the shallow crust and erupt explosively. Alternatively, it might intersect evolved magma pockets in the shallow-level storage region, and so increase the potential for explosive mixed-magma ash eruptions.

  • 3.
    Budd, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Persistent shallow magma storage beneath Katla volcano2014Conference paper (Refereed)
  • 4.
    Budd, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Persistent two-tiered magma plumbing beneath Katla volcano, IcelandIn: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027Article in journal (Refereed)
  • 5.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Magma plumbing architecture in Indonesia and the North Atlantic Igneous Province2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Magma plumbing systems represent the physical framework of magma transport and storage from the source region in the mantle, through the crust, until reaching the surface in a volcanic eruption. Characterising the different aspects of magma plumbing, in particular the distribution of magma storage zones throughout the crust, is of key importance to better understand the behaviour of individual volcanoes. In particular, shallow crustal magma storage and associated magma-crust interaction processes could potentially explain some of the worlds most unpredictable and explosive volcanoes. This thesis studies magma plumbing architecture in the Sunda Arc (Indonesia), and the North Atlantic Igneous Province, based on elemental and isotope geochemistry, and derived petrological modelling.

    In this study, I have employed petrological models, so called geothermobarometers, to calculate pressures and temperatures (P-T) of crustal magma storage. Geothermobarometers are calibrated thermodynamic formulations based on the composition of magmatic minerals and their co-existing melt as a function of the P-T conditions of crystallisation. Using the calculated P-T estimates, I was able to derive the depth of magma storage, and thereby reconstruct the architecture of magma storage systems. A number of different geothermobarometers based on different mineral phases, including plagioclase, clinopyroxene and olivine, were used for this purpose,

    The geothermobarometric modelling was combined with additional elemental and isotope geochemical analyses, as well as collaborations with geophysical investigations. These additional approaches were used to corroborate the findings of the geothermobarometric modelling, and also to model and quantify magma-crust interaction processes that take place during crustal magma storage, such as assimilation of crustal lithologies into the magmatic system.

    The findings of this thesis build upon the growing body of evidence in support of the prevalence of shallow magma storage in different volcanic settings worldwide. This realisation is relevant to volcano monitoring and hazard mitigation worldwide.

    List of papers
    1. Magma plumbing beneath Anak Krakatau volcano, Indonesia: evidence for multiple magma storage regions
    Open this publication in new window or tab >>Magma plumbing beneath Anak Krakatau volcano, Indonesia: evidence for multiple magma storage regions
    Show others...
    2012 (English)In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 163, no 4, p. 631-651Article in journal (Refereed) Published
    Abstract [en]

    Understanding magma plumbing is essential for predicting the behaviour of explosive volcanoes. We investigate magma plumbing at the highly active Anak Krakatau volcano (Indonesia), situated on the rim of the 1883 Krakatau caldera by employing a suite of thermobarometric models. These include clinopyroxene-melt thermobarometry, plagioclase-melt thermobarometry, clinopyroxene composition barometry and olivine-melt thermometry. Petrological studies have previously identified shallow magma storage in the region of 2–8 km beneath Krakatau, while existing seismic evidence points towards mid- to deep-crustal storage zone(s), at 9 and 22 km, respectively. Our results show that clinopyroxene in Anak Krakatau lavas crystallized at a depth of 7–12 km, while plagioclase records both shallow crustal (3–7 km) and sub-Moho (23–28 km) levels of crystallization. These magma storage regions coincide with well-constrained major lithological boundaries in the crust, implying that magma ascent and storage at Anak Krakatau is strongly controlled by crustal properties. A tandem seismic tomography survey independently identified a separate upper crustal (<7 km) and a lower to mid-crustal magma storage region (>7 km). Both petrological and seismic methods are sensitive in detecting magma bodies in the crust, but suffer from various limitations. Combined geophysical and petrological surveys, in turn, offer increased potential for a comprehensive characterization of magma plumbing at active volcanic complexes.

    Keywords
    Anak Krakatau, Thermobarometry, Clinopyroxene, Plagioclase, Magma plumbing, Seismic tomography
    National Category
    Earth and Related Environmental Sciences
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-159368 (URN)10.1007/s00410-011-0690-8 (DOI)000302373800004 ()
    Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
    2. Evidence for high fluid/melt content beneath Krakatau volcano (Indonesia) from local earthquake tomography
    Open this publication in new window or tab >>Evidence for high fluid/melt content beneath Krakatau volcano (Indonesia) from local earthquake tomography
    Show others...
    2011 (English)In: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 206, no 3-4, p. 96-105Article in journal (Refereed) Published
    Abstract [en]

    Within the KRAKMON project for multiparameter monitoring of Anak Krakatau volcano (Indonesia), a network of temporary stations was installed on the islands of the Krakatau complex as well as in the surrounding areas of the Sunda Strait, Sumatra and Java. The network was operated from June 2005 until January 2006. More than 700 local events were recorded during this experiment, and travel times from these events were used to perform a tomographic inversion for P and S velocities and for the Vp/Vs ratio. In this study, special attention was paid to the validation of the computed model based on different tests, such as inversion of independent data subsets and synthetic modeling. Although the network configuration and the distribution of the events are not favorable for high-quality tomographic imaging, we have obtained some important and robust features which give information about sources of volcanic activity in the Krakatau complex. The most interesting feature of this study is a zone of high Vp/Vs ratio beneath the Krakatau complex. At depths down to 4 km depth we observe anticorrelation of higher P- and lower S-velocities that leads to Vp/Vs ratio higher than 2. This is a probable indicator of the presence of partially molten and/or with high fluid content material with a composition corresponding to deeper layers. It is important that the anomaly of high Vp/Vs ratio beneath the Krakatau complex appears to be separated in two parts at a depth of 5-6 km. This fits to results of geobarometric analysis that presume the existence of several levels of magma chambers beneath Anak Krakatau.

    Keywords
    Seismic tomography, Krakatau, Volcanism, Magma chamber
    National Category
    Earth and Related Environmental Sciences
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-160412 (URN)10.1016/j.jvolgeores.2011.06.009 (DOI)000295502900005 ()
    Available from: 2011-10-24 Created: 2011-10-24 Last updated: 2017-12-08Bibliographically approved
    3. The pre-eruptive magma plumbing system of the 2007–2008 dome-forming eruption of Kelut volcano, East Java, Indonesia
    Open this publication in new window or tab >>The pre-eruptive magma plumbing system of the 2007–2008 dome-forming eruption of Kelut volcano, East Java, Indonesia
    Show others...
    2013 (English)In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 166, no 1, p. 275-308Article in journal (Refereed) Published
    Abstract [en]

    Kelut volcano, East Java, is an active volcanic complex hosting a summit crater lake that has been the source of some of Indonesia’s most destructive lahars. In November 2007, an effusive eruption lasting approximately 7 months led to the formation of a 260-m-high and 400-m-wide lava dome that displaced most of the crater lake. The 2007–2008 Kelut dome comprises crystal-rich basaltic andesite with a texturally complex crystal cargo of strongly zoned and in part resorbed plagioclase (An47–94), orthopyroxene (En64–72, Fs24–32, Wo2–4), clinopyroxene (En40–48, Fs14–19, Wo34–46), Ti-magnetite (Usp16–34) and trace amounts of apatite, as well as ubiquitous glomerocrysts of varying magmatic mineral assemblages. In addition, the notable occurrence of magmatic and crustal xenoliths (meta-basalts, amphibole-bearing cumulates, and skarn-type calc-silicates and meta-volcaniclastic rocks) is a distinct feature of the dome. New petrographical, whole rock major and trace element data, mineral chemistry as well as oxygen isotope data for both whole rocks and minerals indicate a complex regime of magma-mixing, decompression-driven resorption, degassing and crystallisation and crustal assimilation within the Kelut plumbing system prior to extrusion of the dome. Detailed investigation of plagioclase textures alongside crystal size distribution analyses provide evidence for magma mixing as a major pre-eruptive process that blends multiple crystal cargoes together. Distinct magma storage zones are postulated, with a deeper zone at lower crustal levels or near the crust-mantle boundary (>15 km depth), a second zone at mid-crustal levels (~10 km depth) and several magma storage zones distributed throughout the uppermost crust (<10 km depth). Plagioclase-melt and amphibole hygrometry indicate magmatic H2O contents ranging from ~8.1 to 8.6 wt.% in the lower crustal system to ~1.5 to 3.3 wt.% in the mid to upper crust. Pyroxene and plagioclase δ18O values range from 5.4 to 6.7 ‰, and 6.5 to 7.6 ‰, respectively. A single whole rock analysis of the 2007–2008 dome lava gave a δ18O value of 7.6 ‰, whereas meta-basaltic and calc-silicate xenoliths are characterised by δ18O values of 6.2 and 10.3 ‰, respectively. Magmatic δ18O values calculated from individual pyroxene and plagioclase analyses range from 5.7 to 7.0 ‰, and 6.2 to 7.4 ‰, respectively. This range in O-isotopic compositions is explained by crystallisation of pyroxenes in the lower to mid-crust, where crustal contamination is either absent or masked by assimilation of material having similar δ18O values to the ascending melts. This population is mixed with isotopically distinct plagioclase and pyroxenes that crystallised from a more contaminated magma in the upper crustal system. Binary bulk mixing models suggest that shallow-level, recycled volcaniclastic sedimentary rocks together with calc-silicates and/or limestones are the most likely contaminants of the 2007–2008 Kelut magma, with the volcaniclastic sediments being dominant.

    Keywords
    Kelut volcano, Sunda arc, Lava dome, CSD, Oxygen isotopes, Magma mixing, Crustal contamination, Volcanic hazards
    National Category
    Geology Geochemistry
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-198047 (URN)10.1007/s00410-013-0875-4 (DOI)000320655900014 ()
    Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2017-12-06Bibliographically approved
    4. Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.
    Open this publication in new window or tab >>Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.
    Show others...
    2015 (English)In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 137-166Article in journal (Refereed) Published
    National Category
    Geosciences, Multidisciplinary
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-240752 (URN)10.1111/geoa.12099 (DOI)000350500400010 ()
    Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2017-12-05Bibliographically approved
    5. Plagioclase mineral chemistry in the Faroe Islands Basalt Group
    Open this publication in new window or tab >>Plagioclase mineral chemistry in the Faroe Islands Basalt Group
    Show others...
    2015 (English)In: Faroe Islands Exploration Conference: Proceedings of the 4th ConferenceArticle in journal (Refereed) In press
    Keywords
    plagioclase, magma plumbing, Large Igneous Province
    National Category
    Geology Geosciences, Multidisciplinary
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-267639 (URN)
    Conference
    The 4th Faroe Islands Exploration Conference, Torshavn, Faroe Islands, 1-2 May 2012
    Available from: 2015-11-25 Created: 2015-11-25 Last updated: 2016-01-13
    6. A geochemical probe into the magma plumbing system and the ancient continental crust underlying the Faroe Islands Basalt Group
    Open this publication in new window or tab >>A geochemical probe into the magma plumbing system and the ancient continental crust underlying the Faroe Islands Basalt Group
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    geobarometry, magma plumbing, AFC, crustal assimilation, isotope geochemistry, plagioclase
    National Category
    Geology
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-267703 (URN)
    Available from: 2015-11-25 Created: 2015-11-25 Last updated: 2017-07-12
    7. Magma transport through communicating vessels explains Hekla's short-fused eruptions
    Open this publication in new window or tab >>Magma transport through communicating vessels explains Hekla's short-fused eruptions
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    Thermobarometry, plagioclase, clinopyroxene, hazard mitigation, magma plumbing
    National Category
    Geology
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-267700 (URN)
    Available from: 2015-11-25 Created: 2015-11-25 Last updated: 2016-01-13
    8. Persistent two-tiered magma plumbing beneath Katla volcano, Iceland
    Open this publication in new window or tab >>Persistent two-tiered magma plumbing beneath Katla volcano, Iceland
    (English)In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027Article in journal (Refereed) Submitted
    National Category
    Geology
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-267448 (URN)
    Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2017-12-01
  • 6.
    Dahrén, Börje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Emeleus, C.H.
    Mattson, T.
    Berg, Sylvia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    3D-model of the Rum central complex2014Conference paper (Refereed)
  • 7.
    Dahrén, Börje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Barker, Abigail
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Meade, Fiona C.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Holm, Paul Martin
    University of Copenhagen, Department of Geosciences and Natural Resource Management, Øster Voldgade 10, Copenhagen DK-1350, Denmark.
    Søager, Nina
    GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany.
    Plagioclase mineral chemistry in the Faroe Islands Basalt Group2015In: Faroe Islands Exploration Conference: Proceedings of the 4th ConferenceArticle in journal (Refereed)
  • 8.
    Dahrén, Börje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Andersson, Ulf B.
    Chadwick, Jane P.
    Gardner, Mairi F.
    Jaxybulatov, Kairly
    Koulakov, Ivan
    Magma plumbing beneath Anak Krakatau volcano, Indonesia: evidence for multiple magma storage regions2012In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 163, no 4, p. 631-651Article in journal (Refereed)
    Abstract [en]

    Understanding magma plumbing is essential for predicting the behaviour of explosive volcanoes. We investigate magma plumbing at the highly active Anak Krakatau volcano (Indonesia), situated on the rim of the 1883 Krakatau caldera by employing a suite of thermobarometric models. These include clinopyroxene-melt thermobarometry, plagioclase-melt thermobarometry, clinopyroxene composition barometry and olivine-melt thermometry. Petrological studies have previously identified shallow magma storage in the region of 2–8 km beneath Krakatau, while existing seismic evidence points towards mid- to deep-crustal storage zone(s), at 9 and 22 km, respectively. Our results show that clinopyroxene in Anak Krakatau lavas crystallized at a depth of 7–12 km, while plagioclase records both shallow crustal (3–7 km) and sub-Moho (23–28 km) levels of crystallization. These magma storage regions coincide with well-constrained major lithological boundaries in the crust, implying that magma ascent and storage at Anak Krakatau is strongly controlled by crustal properties. A tandem seismic tomography survey independently identified a separate upper crustal (<7 km) and a lower to mid-crustal magma storage region (>7 km). Both petrological and seismic methods are sensitive in detecting magma bodies in the crust, but suffer from various limitations. Combined geophysical and petrological surveys, in turn, offer increased potential for a comprehensive characterization of magma plumbing at active volcanic complexes.

  • 9.
    Dahrén, Börje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Barker, Abigail K.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Meade, Fiona C
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Millet, John M
    Volcanic Basin Petroleum Research AS, Forskningsparken, Gaustadalléen 21, N-0349 Oslo, Norway.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy.
    Holm, Paul Martin
    University of Copenhagen, Department of Geosciences and Natural Resource Management, Øster Voldgade 10, Copenhagen DK-1350, Denmark b.
    Søager, Nina
    GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany.
    Morton, Andrew C
    HM Research Associates, 2 Clive Road, Balsall Common, West Midlands CV7 7DW, UK.
    Harris, Chris H
    Department of Geological Science, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
    Hilton, David R
    Geosciences Research Division, Scripps Institution of Oceanography, UCSD La Jolla, CA 92093-0244, USA.
    Ellam, Robert
    Scottish Universities Environmental Research Centre, East Kilbride, Scotland, UK.
    A geochemical probe into the magma plumbing system and the ancient continental crust underlying the Faroe Islands Basalt GroupManuscript (preprint) (Other academic)
  • 10.
    Dahrén, Börje
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Krumbholz, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Albers, Elmar
    Petrology of the Ocean Crust, Department of Geosciences, University of Bremen, Klagenfurter Straße (GEO), Bremen, Germany.
    Barker, Abigail K.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Magma transport through communicating vessels explains Hekla's short-fused eruptionsManuscript (preprint) (Other academic)
  • 11.
    Jamshidi, K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Ghasemi, H.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Sadeghian, M.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran2015In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 6, no 1, p. 49-72Article in journal (Refereed)
    Abstract [en]

    Subduction-related adakite-type intrusive rocks emplaced into the late Cretaceous-Paleocene Sabzevar ophiolite zone, northeast Iran, range from Mg-andesite to rhyodacite in composition. Here we investigate the magma supply system to these subvolcanic intrusive rocks by applying thermobarometric mineral and mineral-melt equilibrium models, including amphibole thermobarometry, plagioclase-melt thermobarometry and clinopyroxene-melt barometry. Based on the results of these thermobarometric models, plagioclase crystallized dominantly at pressures of similar to 350 (130 to 468) MPa, while amphiboles record both low pressures (similar to 300 MPa) and very high pressures (> 700 MPa) of crystallization. The latter is supported by the calculated pressures for clinopyroxene crystallization (550 to 730 MPa). The association of amphibole with clinopyroxene and no plagioclase in the most primitive samples (Mg-andesites) is consistent with amphibole fractionation from very hydrous magmas at deep crustal levels of the plumbing system, which may have been a key process in intensifying adakite-type affinities in this rock suite. Barometry, combined with frequent disequilibrium features such as oscillatory-zoned and sieve-textured plagioclase crystals with An-rich overgrowths in more evolved samples, implies that final magma differentiation occurred in an open upper crustal magma system that developed progressively stronger compositional modifications during high-level magma storage.

  • 12. Jaxybulatov, Kairly
    et al.
    Koulakov, Ivan
    Ibs-von Seht, Malte
    Klinge, Klaus
    Reichert, Christian
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Evidence for high fluid/melt content beneath Krakatau volcano (Indonesia) from local earthquake tomography2011In: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 206, no 3-4, p. 96-105Article in journal (Refereed)
    Abstract [en]

    Within the KRAKMON project for multiparameter monitoring of Anak Krakatau volcano (Indonesia), a network of temporary stations was installed on the islands of the Krakatau complex as well as in the surrounding areas of the Sunda Strait, Sumatra and Java. The network was operated from June 2005 until January 2006. More than 700 local events were recorded during this experiment, and travel times from these events were used to perform a tomographic inversion for P and S velocities and for the Vp/Vs ratio. In this study, special attention was paid to the validation of the computed model based on different tests, such as inversion of independent data subsets and synthetic modeling. Although the network configuration and the distribution of the events are not favorable for high-quality tomographic imaging, we have obtained some important and robust features which give information about sources of volcanic activity in the Krakatau complex. The most interesting feature of this study is a zone of high Vp/Vs ratio beneath the Krakatau complex. At depths down to 4 km depth we observe anticorrelation of higher P- and lower S-velocities that leads to Vp/Vs ratio higher than 2. This is a probable indicator of the presence of partially molten and/or with high fluid content material with a composition corresponding to deeper layers. It is important that the anomaly of high Vp/Vs ratio beneath the Krakatau complex appears to be separated in two parts at a depth of 5-6 km. This fits to results of geobarometric analysis that presume the existence of several levels of magma chambers beneath Anak Krakatau.

  • 13.
    Jeffery, Adam J.
    et al.
    School of Physical and Geographical Sciences, Keele University, UK.
    Gertisser, Ralf
    School of Physical and Geographical Sciences, Keele University, UK.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, Ester M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Harris, Chris
    University of Cape Town, South Africa.
    Tindle, Andrew G.
    CEPSAR (Centre for Earth, Planetary, Space and Astronomy Research), The Open University, UK.
    Preece, Katie
    University of East Anglia.
    O'Driscoll, Brain
    Humaida, Hanik
    Balai Penyelidikan dan Pengembangan Teknologi, Indonesia.
    Chadwick, Jane P.
    Science Gallery, Trinity College Dublin, Dublin.
    The pre-eruptive magma plumbing system of the 2007–2008 dome-forming eruption of Kelut volcano, East Java, Indonesia2013In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 166, no 1, p. 275-308Article in journal (Refereed)
    Abstract [en]

    Kelut volcano, East Java, is an active volcanic complex hosting a summit crater lake that has been the source of some of Indonesia’s most destructive lahars. In November 2007, an effusive eruption lasting approximately 7 months led to the formation of a 260-m-high and 400-m-wide lava dome that displaced most of the crater lake. The 2007–2008 Kelut dome comprises crystal-rich basaltic andesite with a texturally complex crystal cargo of strongly zoned and in part resorbed plagioclase (An47–94), orthopyroxene (En64–72, Fs24–32, Wo2–4), clinopyroxene (En40–48, Fs14–19, Wo34–46), Ti-magnetite (Usp16–34) and trace amounts of apatite, as well as ubiquitous glomerocrysts of varying magmatic mineral assemblages. In addition, the notable occurrence of magmatic and crustal xenoliths (meta-basalts, amphibole-bearing cumulates, and skarn-type calc-silicates and meta-volcaniclastic rocks) is a distinct feature of the dome. New petrographical, whole rock major and trace element data, mineral chemistry as well as oxygen isotope data for both whole rocks and minerals indicate a complex regime of magma-mixing, decompression-driven resorption, degassing and crystallisation and crustal assimilation within the Kelut plumbing system prior to extrusion of the dome. Detailed investigation of plagioclase textures alongside crystal size distribution analyses provide evidence for magma mixing as a major pre-eruptive process that blends multiple crystal cargoes together. Distinct magma storage zones are postulated, with a deeper zone at lower crustal levels or near the crust-mantle boundary (>15 km depth), a second zone at mid-crustal levels (~10 km depth) and several magma storage zones distributed throughout the uppermost crust (<10 km depth). Plagioclase-melt and amphibole hygrometry indicate magmatic H2O contents ranging from ~8.1 to 8.6 wt.% in the lower crustal system to ~1.5 to 3.3 wt.% in the mid to upper crust. Pyroxene and plagioclase δ18O values range from 5.4 to 6.7 ‰, and 6.5 to 7.6 ‰, respectively. A single whole rock analysis of the 2007–2008 dome lava gave a δ18O value of 7.6 ‰, whereas meta-basaltic and calc-silicate xenoliths are characterised by δ18O values of 6.2 and 10.3 ‰, respectively. Magmatic δ18O values calculated from individual pyroxene and plagioclase analyses range from 5.7 to 7.0 ‰, and 6.2 to 7.4 ‰, respectively. This range in O-isotopic compositions is explained by crystallisation of pyroxenes in the lower to mid-crust, where crustal contamination is either absent or masked by assimilation of material having similar δ18O values to the ascending melts. This population is mixed with isotopically distinct plagioclase and pyroxenes that crystallised from a more contaminated magma in the upper crustal system. Binary bulk mixing models suggest that shallow-level, recycled volcaniclastic sedimentary rocks together with calc-silicates and/or limestones are the most likely contaminants of the 2007–2008 Kelut magma, with the volcaniclastic sediments being dominant.

  • 14.
    Rhodes, Emma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Centre for Natural Hazards and Disaster Science, Sweden.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Centre for Natural Hazards and Disaster Science, Sweden.
    Parker, Charles F.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Government. Centre for Natural Hazards and Disaster Science, Sweden.
    Barker, Abigail
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Centre for Natural Hazards and Disaster Science, Sweden.
    Dahrén, Börje
    Uppsala University, University Library.
    What is the role of Wiki during volcanic eruptions?2019Conference paper (Other academic)
    Abstract [en]

    A team of scientists from the Centre of Natural Hazards and Disaster Science (www.cnds.se) and Uppsala University are planning a study on the role of Wikipedia during volcanic eruptions.

    Pageview statistics show a spike of up to 200 000 views (e.g. Anak Krakatau eruption and associated tsunami in December 2018) at the onset of a volcanic event. In acknowledgement of this, the team want to explore the role of Wikipedia as a disaster response resource during such events, when accurate and readily accessible information can save lives. The poster will outline our current approach to this project, propose suitable methods and illustrate the work in progress.

  • 15.
    Troll, Valentin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, Ester Muños
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Harris, C.
    Berg, Sylvia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Hilton, D.R.
    Freda, C.
    Reconstructing the plumbing system of Krakatau volcano2014Conference paper (Refereed)
  • 16.
    Troll, Valentin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Jolis, Ester Muños
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Budd, David
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Schwarzkopf, L.M.
    Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 137-166Article in journal (Refereed)
  • 17.
    Troll, Valentin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, Ester Muños
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Harris, C.
    Berg, Sylvia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Hilton, D.R.
    Freda, C.
    Magma storage at Krakatau volcanic complex2014Conference paper (Refereed)
  • 18.
    Troll, Valentin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Klügel, A
    3Institute of Geosciences, University of Bremen, Germany.
    Longpré, M.-A
    Dept. of Earth and Planetary Sciences, McGill University, Canada.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Deegan, Frances
    Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockhom, Sweden..
    Carracedo, J.C
    Dept. of Physics (Geology), GEOVOL, University of Las Palmas, Gran Canaria, Spain.
    Wiesmaier, S
    Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Kueppers, U
    Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Hansteen, T. H
    Leibniz-Institute for Oceanography, IFM-GEOMAR, Kiel, Germany.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy.
    Budd, David
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, Ester
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jonsson, E
    Geological Survey of Sweden, Uppsala, Sweden.
    Meade, Fiona
    School of Geographical and Earth Sciences, University of Glasgow, UK.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, South Africa.
    Berg, Sylvia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mancini, Lucia
    SYRMEP Group, Sincrotrone Trieste S.C.p.A, Basovizza, Trieste, Italy.
    Polacci, M
    Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, 56124 Pisa, Italy.
    Pedroza, Kirsten
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption2012In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 3, no 1, p. 97-110Article in journal (Refereed)
    Abstract [en]

    A submarine eruption started off the south coast of El Hierro, Canary Islands, on 10 October 2011 and continues at the time of this writing (February 2012). In the first days of the event, peculiar eruption products were found floating on the sea surface, drifting for long distances from the eruption site. These specimens, which have in the meantime been termed "restingolites" (after the close-by village of La Restinga), appeared as black volcanic "bombs" that exhibit cores of white and porous pumice-like material. Since their brief appearance, the nature and origin of these "floating stones" has been vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The "restingolites" have been proposed to be either (i) juvenile high-silica magma (e. g. rhyolite), (ii) remelted magmatic material (trachyte), (iii) altered volcanic rock, or (iv) reheated hyaloclastites or zeolite from the submarine slopes of El Hierro. Here, we provide evidence that supports yet a different conclusion. We have analysed the textures and compositions of representative "restingolites" and compared the results to previous work on similar rocks found in the Canary Islands. Based on their high-silica content, the lack of igneous trace element signatures, the presence of remnant quartz crystals, jasper fragments and carbonate as well as wollastonite (derived from thermal overprint of carbonate) and their relatively high oxygen isotope values, we conclude that "restingolites" are in fact xenoliths from pre-island sedimentary layers that were picked up and heated by the ascending magma, causing them to partially melt and vesiculate. As they are closely resembling pumice in appearance, but are xenolithic in origin, we refer to these rocks as "xeno-pumice". The El Hierro xeno-pumices hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies beneath the Canary Islands as well as in similar Atlantic islands that rest on sediment-covered ocean crust (e. g. Cape Verdes, Azores). The occurrence of "restingolites" indicates that crustal recycling is a relevant process in ocean islands, too, but does not herald the arrival of potentially explosive high-silica magma in the active plumbing system beneath El Hierro.

  • 19.
    Weis, Franz A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Skogby, Henrik
    Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden..
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Department of Physics (GEOVOL), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Department of Geological Science, Stockholm University, Stockholm, Sweden.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Magmatic water contents determined through clinopyroxene: Examples from the Western Canary Islands, Spain2015In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 16, no 7, p. 2127-2146Article in journal (Refereed)
    Abstract [en]

    Water is a key parameter in magma genesis, magma evolution, and resulting eruption styles, because it controls the density, the viscosity, as well as the melting and crystallization behavior of a melt. The parental water content of a magma is usually measured through melt inclusions in minerals such as olivine, a method which may be hampered, however, by the lack of melt inclusions suitable for analysis, or postentrapment changes in their water content. An alternative way to reconstruct the water content of a magma is to use nominally anhydrous minerals (NAMs), such as pyroxene, which take up low concentrations of hydrogen as a function of the magma's water content. During magma degassing and eruption, however, NAMs may dehydrate. We therefore tested a method to reconstruct the water contents of dehydrated clinopyroxene phenocrysts from the Western Canary islands (n=28) through rehydration experiments followed by infrared and Mossbauer spectroscopy. Employing currently available crystal/melt partitioning data, the results of the experiments were used to calculate parental water contents of 0.710.07 to 1.490.15 wt % H2O for Western Canary magmas during clinopyroxene crystallization at upper mantle conditions. This H2O range is in agreement with calculated water contents using plagioclase-liquid-hygrometry, and with previously published data for mafic lavas from the Canary Islands and comparable ocean island systems elsewhere. Utilizing NAMs in combination with hydrogen treatment can therefore serve as a proxy for pre-eruptive H2O contents, which we anticipate becoming a useful method applicable to mafic rocks where pyroxene is the main phenocryst phase.

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