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  • 1.
    Andersson, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Almqvist, Bjarne S. G.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Burchardt, Steffi
    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.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Snowball, Ian
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Natural Resources and Sustainable Development.
    Kubler, Lutz
    Geol Survey Sweden, Uppsala, Sweden..
    Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 27635Article in journal (Refereed)
    Abstract [en]

    Magma transport through the Earth's crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have proved elusive. Anisotropy of magnetic susceptibility (AMS) in magmatic sheets is often interpreted as primary magma flow, but magnetic fabrics can be modified by post-emplacement processes, making interpretation of AMS data ambiguous. Here we present AMS data from cone-sheets in the Alno carbonatite complex, central Sweden. We discuss six scenarios of syn- and post-emplacement processes that can modify AMS fabrics and offer a conceptual framework for systematic interpretation of magma movements in sheet intrusions. The AMS fabrics in the Alno cone-sheets are dominantly oblate with magnetic foliations parallel to sheet orientations. These fabrics may result from primary lateral flow or from sheet closure at the terminal stage of magma transport. As the cone-sheets are discontinuous along their strike direction, sheet closure is the most probable process to explain the observed AMS fabrics. We argue that these fabrics may be common to cone-sheets and an integrated geology, petrology and AMS approach can be used to distinguish them from primary flow fabrics.

  • 2.
    Andersson, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Dehghannejad, Mahdieh
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Ask, Maria
    Carbonatite ring-complexes explained by caldera-style volcanism2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, p. 1677-Article in journal (Refereed)
    Abstract [en]

    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alno carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at similar to 3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas.

  • 3.
    Barker, Abigail
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Holm, Paul Martin
    Unniversity of Copenhagen.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    The role of eclogite in the mantle heterogeneity at Cape Verde2014In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 168, no 3, p. 1052-Article in journal (Refereed)
    Abstract [en]

    The Cape Verde hotspot, like many other Ocean Island Basalt provinces, demonstrates isotopic heterogeneity on a 100–200 km scale. The heterogeneity is represented by the appearance of an EM1-like component at several of the southern islands and with a HIMU-like component present throughout the archipelago. Where the EM1-like component is absent, a local DMM-like component replaces the EM1-like component. Various source lithologies, including peridotite, pyroxenite and eclogite have been suggested to contribute to generation of these heterogeneities; however, attempts to quantify such contributions have been limited. We apply the minor elements in olivine approach (Sobolev et al. in Nature 434:590–597, 2005; Science, doi:10.1126/science.1138113,2007), to determine and quantify the contributions of peridotite, pyroxenite and eclogite melts to the mantle heterogeneity observed at Cape Verde. Cores of olivine phenocrysts of the Cape Verde volcanics have low Mn/FeO and low Ni*FeO/MgO that deviate from the negative trend of the global array. The global array is defined by mixing between peridotite and pyroxenite, whereas the Cape Verde volcanics indicate contribution of an additional eclogite source. Eclogite melts escape reaction with peridotite either by efficient extraction in an area of poor mantle flow or by reaction of eclogite melts with peridotite, whereby an abundance of eclogite can seal off the melt from further reaction. Temporal trends of decreasing Mn/FeO indicate that the supply of eclogite melts is increasing. Modelling suggests the local DMM-like end-member is formed from a relatively peridotite-rich melt, while the EM1-like end-member has a closer affinity to a mixed peridotite–pyroxenite–eclogite melt. Notably the HIMU-like component ranges from pyroxenite–peridotite-rich melt to one with up to 77 % eclogite melt as a function of time, implying that sealing of melt pathways is becoming more effective.

  • 4.
    Barker, Abigail K.
    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.
    Ellam, R.M.
    Hansteen, T.H.
    Haris, C.
    Stillman, C.J.
    Andersson, A.
    Magmatic evolution of the Cadamosto Seamount, Cape Verde: Beyond the spatial extent of EM12012In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 163, no 6, p. 949-965Article in journal (Refereed)
    Abstract [en]

    The Cadamosto Seamount is an unusual volcanic centre from Cape Verde, characterised by dominantly evolved volcanics, in contrast to the typically mafic volcanic centres at Cape Verde that exhibit only minor volumes of evolved volcanics. The magmatic evolution of Cadamosto Seamount is investigated to quantify the role of magma-crust interaction and thus provide a perspective on evolved end-member volcanism of Cape Verde. The preservation of mantle source signatures by Nd-Pb isotopes despite extensive magmatic differentiation provides new insights into the spatial distribution of mantle heterogeneity in the Cape Verde archipelago. Magmatic differentiation from nephelinite to phonolite involves fractional crystallisation of clinopyroxene, titanite, apatite, biotite and feldspathoids, with extensive feldspathoid accumulation being recorded in some evolved samples. Clinopyroxene crystallisation pressures of 0.38-0.17 GPa for the nephelinites constrain this extensive fractional crystallisation to the oceanic lithosphere, where no crustal assimilants or rafts of subcontinental lithospheric mantle are available. In turn, magma-crust interaction has influenced the Sr, O and S isotopes of the groundmass and late crystallising feldspathoids, which formed at shallow crustal depths reflecting the availability of oceanic sediments and anhydrite precipitated in the ocean crust. The Nd-Pb isotopes have not been affected by these processes of magma-crust interaction and hence preserve the mantle source signature. The Cadamosto Seamount samples have high Pb-206/Pb-204 (> 19.5), high epsilon Nd (+6 to +7) and negative Delta 8/4Pb, showing affinity with the northern Cape Verde islands as opposed to the adjacent southern islands. Hence, the Cadamosto Seamount in the west is located spatially beyond the EM1-like component found further east. This heterogeneity is not encountered in the oceanic lithosphere beneath the Cadamosto Seamount despite greater extents of fractional crystallisation at oceanic lithospheric depths than the islands of Fogo and Santiago. Our data provide new evidence for the complex geometry of the chemically zoned Cape Verde mantle source.

  • 5.
    Barker, Abigail
    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. Univ Las Palmas, GEOVOL, La Palmas Gran Canaria 35017, Spain.
    Carracedo, Juan Carlos
    Univ Las Palmas, GEOVOL, La Palmas Gran Canaria 35017, Spain.
    Nicholls, Peter A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    The magma plumbing system for the 1971 Teneguía eruption on La Palma, Canary Islands2015In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 170, no 5-6, article id 54Article in journal (Refereed)
    Abstract [en]

    The 1971 Teneguía eruption is the most recent volcanic event of the Cumbre Vieja rift zone on La Palma. The eruption produced basanite lavas that host xenoliths, which we investigate to provide insight into the processes of differentiation, assimilation and magma storage beneath La Palma. We compare our results to the older volcanomagmatic systems of the island with the aim to reconstruct the temporal development of the magma plumbing system beneath La Palma.

    The 1971 lavas are clinopyroxene-olivine-phyric basanites that contain augite, sodic-augite and Aluminium augite. Kaersutite cumulate xenoliths host olivine, clinopyroxene including sodic-diopside, and calcic-amphibole, whereas an analysed leucogabbro xenolith hosts plagioclase, sodic-augite-diopside, calcic-amphibole and hauyne. Mineral and mineral-melt thermobarometry indicate that clinopyroxene and plagioclase in the 1971 Teneguía lavas crystallised at 20 to 45 km depth, coinciding with clinopyroxene and calcic-amphibole crystallisation in the kaersutite cumulate xenoliths at 25 to 45 km and clinopyroxene, calcic-amphibole and plagioclase crystallisation in the leucogabbro xenolith at 30 to 50 km.

    Combined mineral chemistry and thermobarometry suggest that the magmas had already crystallised, differentiated and formed multiple crystal populations in the oceanic lithospheric mantle. Notably, the magmas that supplied the 1949 and 1971 events appear to have crystallised deeper than the earlier Cumbre Vieja magmas, which suggests progressive underplating beneath the Cumbre Vieja rift zone. In addition, the lavas and xenoliths of the 1971 event crystallised at a common depth, indicating a reused plumbing system and progressive recycling of Ocean Island plutonic complexes during subsequent magmatic activity. 

  • 6.
    Berg, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, V.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Freda, C.
    Mancini, L.
    Masotta, M.
    Brun, F.
    Blythe, L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, E. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Annersten, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Barker, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Experimental simulation of crustal volatile release in magmatic conduits2012Conference paper (Other academic)
  • 7.
    Berg, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Riishuus, M. S.
    Burchardt, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Petrogenesis of Voluminous Silicic Magma in Northeast Iceland2012Conference paper (Refereed)
    Abstract [en]

    Neogene silicic volcanic complexes in the greater Borgarfjörður eystri area, NE-Iceland, are the focus of a petrological and geochemical investigation. The region contains the second-most voluminous occurrence of silicic rocks in Iceland, including caldera structures, inclined sheet swarms, extensive ignimbrite sheets, sub-volcanic rhyolites and silicic lava flows. Despite the relevance of these rocks to understand the generation of evolved magmas in Iceland, the area is geologically poorly studied [c.f. 1, 2, 3].

    The voluminous occurrence of evolved rocks in Iceland (10-12 %) is very unusual for an ocean island or a mid-oceanic ridge, with a typical signal of magmatic bimodality, often called “Bunsen-Daly” compositional gap [e.g. 4, 5, 6]. The Bunsen-Daly Gap is a long-standing and fundamental issue in petrology and difficult to reconcile with continuous fractional crystallization as a dominant process in magmatic differentiation [7]. This implies that partial melting of hydrothermally altered crust may play a significant role. Our aim is to contribute to a solution to this issue by unravelling the origin, timing and evolution of voluminous evolved rhyolites in NE-Iceland.

    We use a combined petrological, textural, experimental and in-situ isotope approach on a comprehensive sample suite of intrusive and extrusive rocks, ranging from basaltic to silicic compositions. We are performing major, trace element and Sr-Nd-Hf-Pb-He-O isotope geochemistry, as well as U-Pb geochronology and Ar/Ar geochronology on rocks and mineral separates. Zircon oxygen isotope analysis will be performed in conjuction with zircon U-Pb geochronology for further assessment of the role of processes such as partial melting of hydrated country rock and/or fractional crystallization in generating Icelandic rhyolites. In addition, high pressure-temperature partial melting experiments aim to reproduce and further constrain natural processes. Using the combined data set we intend to produce a comprehensive and quantitative analysis of rhyolite petrogenesis, and of the temporal, structural and geochemical evolution of silicic volcanism in NE-Iceland. The chosen field area serves as a good analogue for active central volcanoes in Iceland, such as Askja and Krafla, where interaction of basaltic and more evolved magma has led to explosive eruptions.

     

     

    [1] Gústafsson (1992) PhD dissertation, Berlin University. [2] Martin & Sigmarsson (2010) Lithos 116, 129–144. [3] Burchardt, Tanner, Troll, Krumbholz & Gustafsson (2011) G3 12 (7), Q0AB09. [4] Bunsen (1851) Annalen der Physik und Chemie 159 (6), 197-272. [5] Daly (1925) Proceedings of the American Academy of Arts and Sciences 60 (1), 3-80. [6] Barth, Correns & Eskola (1939) Die Entstehung der Gesteine. Springer Verlag, Berlin. [7] Bowen (1928) The evolution of the igneous rocks. Princeton University Press.

     

  • 8.
    Berg, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Riishuus, M. S.
    Burchardt, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Eroded Neogene Silicic Central Volcanoes in Northeast Iceland Revisited2012Conference paper (Refereed)
  • 9.
    Berg, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Riishuus, M. S.
    Burchardt, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Silicic Magma Genesis in Neogene Central Volcanoes in Northeast Iceland2012Conference paper (Refereed)
    Abstract [en]

    We report on a geological expedition to NE Iceland in August 2011. A comprehensive sample suite of intrusive and extrusive rocks, ranging from basaltic to silicic compositions, was collected from the Neogene silicic central volcanic complexes in the region between Borgarfjörður eystri and Loðmundarfjörður. The area contains the second-most voluminous occurrence of silicic rocks in Iceland, including caldera structures, inclined sheet swarms, extensive ignimbrite sheets, sub-volcanic rhyolites and silicic lava flows. Yet it is one of Iceland's geologically least known areas (c.f. Gústafsson, 1992; Martin & Sigmarsson, 2010; Burchardt et al., 2011). The voluminous occurrence of evolved rocks in Iceland (10-12 %) is very unusual for an ocean island or a mid-oceanic ridge, with a typical signal of magmatic bimodality, often called "Bunsen-Daly" compositional gap (e.g. Bunsen, 1851; Daly, 1925; Barth et al., 1939). The Bunsen-Daly Gap is a long-standing fundamental issue in petrology and difficult to reconcile with continuous fractional crystallization as a dominant process in magmatic differentiation (Bowen, 1928), implying that hydrothermal alteration and crustal melting may play a significant role. Our aim is to contribute to a solution of this issue by unravelling the occurrence of voluminous evolved rhyolites in NE Iceland. We will use a combined petrological, textural, experimental and in-situ isotope approach. We plan to perform major, trace element and Sr-Nd-Hf-Pb-He-O isotope geochemistry, as well as U/Pb and Ar/Ar geochronology on rocks and mineral separates. In addition, high pressure-temperature partial melting experiments aim to reproduce and further constrain natural processes. Using the combined data set we intend to produce a comprehensive and quantitative analysis of rhyolite petrogenesis, and of the temporal, structural and geochemical evolution of the silicic volcanism in NE Iceland. The chosen field area serves as a good analogue for active central volcanoes in Iceland, such as Askja and Krafla, where a close interaction of basaltic and more evolved magma has led to explosive eruptions.

  • 10.
    Berg, Sylvia E.
    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. Univ Las Palmas Gran Canaria, GEOVOL, Las Palmas Gran Canaria, Spain.
    Deegan, Frances M.
    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. Georg August Univ Gottingen, Geosci Ctr, Goldschmidtstr 1-3, D-37077 Gottingen, Germany.
    Mancini, Lucia
    SCpA, Elettra Sincrotrone Trieste, SS 14 Km 163,5 AREA Sci Pk, I-34149 Trieste, Italy.
    Polacci, Margherita
    Univ Manchester, Sch Earth & Environm Sci, Williamson Bldg,Oxford Rd, Manchester M13 9PL, Lancs, England.
    Carracedo, Juan Carlos
    Univ Las Palmas Gran Canaria, GEOVOL, Las Palmas Gran Canaria, Spain.
    Soler, Vicente
    CSIC, Estn Vulcanol Canarias, Avda Astr Fco Sanchez 3, Tenerife 38206, Spain.
    Arzilli, Fabio
    SCpA, Elettra Sincrotrone Trieste, SS 14 Km 163,5 AREA Sci Pk, I-34149 Trieste, Italy.; Univ Manchester, Sch Earth & Environm Sci, Williamson Bldg,Oxford Rd, Manchester M13 9PL, Lancs, England.
    Brun, Francesco
    SCpA, Elettra Sincrotrone Trieste, SS 14 Km 163,5 AREA Sci Pk, I-34149 Trieste, Italy.; Univ Trieste, Dept Engn & Architecture, Via A Valerio 10, I-34127 Trieste, Italy.
    Heterogeneous vesiculation of 2011 El Hierro xeno-pumice revealed by X-ray computed microtomography2016In: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 78, no 12, article id 85Article in journal (Refereed)
    Abstract [en]

    During the first week of the 2011 El Hierro submarine eruption, abundant light-coloured pumiceous, high-silica volcanic bombs coated in dark basanite were found floating on the sea. The composition of the light-coloured frothy material ('xeno-pumice') is akin to that of sedimentary rocks from the region, but the textures resemble felsic magmatic pumice, leaving their exact mode of formation unclear. To help decipher their origin, we investigated representative El Hierro xeno-pumice samples using X-ray computed microtomography for their internal vesicle shapes, volumes, and bulk porosity, as well as for the spatial arrangement and size distributions of vesicles in three dimensions (3D). We find a wide range of vesicle morphologies, which are especially variable around small fragments of rock contained in the xeno-pumice samples. Notably, these rock fragments are almost exclusively of sedimentary origin, and we therefore interpret them as relicts an the original sedimentary ocean crust protolith(s). The irregular vesiculation textures observed probably resulted from pulsatory release of volatiles from multiple sources during xeno-pumice formation, most likely by successive release of pore water and mineral water during incremental heating and decompression of the sedimentary protoliths.

  • 11.
    Berg, Sylvia
    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.
    Burchardt, Steffi
    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.
    Riishuus, Morten S.
    Nordic Volcanological Center. Institute of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik.
    Whitehouse, Martin J.
    Dept. of Geosciences, Swedish Museum of Natural History, SE-104 05, Stockholm, Sweden.
    Harris, Chris
    Dept. of Geological Sciences, University of Cape Town, Rondebosch, South Africa,.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    Ellis, Ben S.
    Inst. f. Geochemie und Petrologie, ETH, Clausiusstrasse 25, 8092, Zurich, Switzerland.
    Krumbholz, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Gústafsson, Ludvik E.
    Samband Islenskra Sveitarfélag, Borgartúni 30, pósthólf 8100, 128 Reykjavik, Iceland.
    Rapid high-silica magma generation in basalt-dominated rift settings2015Conference paper (Other academic)
  • 12.
    Berg, Sylvia
    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.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Riishuus, M.
    Krumbholz, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Gústafsson, L.E.
    Iceland's best kept secret2014In: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 30, no 2, p. 54-60Article in journal (Refereed)
    Abstract [en]

    The ‘forgotten fjords’ and ‘deserted inlets’ of NE-Iceland, in the region between Borgarfjörður Eystri and Loðmundarfjörður, are not only prominent because of their pristine landscape, their alleged elfin settlements, and the puffins that breed in the harbour, but also for their magnificent geology. From a geological point of view, the area may hold Iceland's best kept geological secret. The greater Borgarfjörður Eystri area hosts mountain chains that consist of voluminous and colourful silicic rocks that are concentrated within a surprisingly small area (Fig. 1), and that represent the second-most voluminous occurrence of silicic rocks in the whole of Iceland. In particular, the presence of unusually large volumes of ignimbrite sheets documents extremely violent eruptions during the Neogene, which is atypical for this geotectonic setting. As a group of geoscientists from Uppsala University (Sweden) and the Nordic Volcanological Center (NordVulk, Iceland) we set out to explore this remote place, with the aim of collecting material that may allow us to unravel the petrogenesis of these large volumes of silicic rocks. This effort could provide an answer to a long-standing petrological dilemma; the question of how silicic continental crust is initially created. Here we document on our geological journey, our field strategy, and describe our field work in the remote valleys of NE-Iceland.

  • 13.
    Berg, Sylvia
    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.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Riishuus, M.S.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Harris, C.
    Whitehouse, M.J.
    Gustafsson, L.E.
    Making Earth’s earliest continental crust: an analogue from voluminous Neogene silicic volcanism in NE-Iceland2014Conference paper (Refereed)
    Abstract [en]

    Borgarfjörður Eystri in NE-Iceland represents the second-most voluminous exposure of silicic eruptive rocksin Iceland and is a superb example of bimodal volcanism (Bunsen-Daly gap), which represents a long-standingcontroversy that touches on the problem of crustal growth in early Earth. The silicic rocks in NE-Iceland approach25 % of the exposed rock mass in the region (Gústafsson et al., 1989), thus they significantly exceed the usual≤ 12 % in Iceland as a whole (e.g. Walker, 1966; Jonasson, 2007). The origin, significance, and duration of thevoluminous (> 300 km3) and dominantly explosive silicic activity in Borgarfjörður Eystri is not yet constrained(c.f. Gústafsson, 1992), leaving us unclear as to what causes silicic volcanism in otherwise basaltic provinces.Here we report SIMS zircon U-Pb ages and δ18O values from the region, which record the commencement ofsilicic igneous activity with rhyolite lavas at 13.5 to 12.8 Ma, closely followed by large caldera-forming ignimbriteeruptions from the Breiðavik and Dyrfjöll central volcanoes (12.4 Ma). Silicic activity ended abruptly with dacitelava at 12.1 Ma, defining a ≤ 1 Myr long window of silicic volcanism. Magma δ18O values estimated fromzircon range from 3.1 to 5.5 (± 0.3; n = 170) and indicate up to 45 % assimilation of a low-δ18O component (e.g.typically δ18O = 0 h Bindeman et al., 2012). A Neogene rift relocation (Martin et al., 2011) or the birth of anoff-rift zone to the east of the mature rift associated with a thermal/chemical pulse in the Iceland plume (Óskarsson& Riishuus, 2013), likely brought mantle-derived magma into contact with fertile hydrothermally-altered basalticcrust. The resulting interaction triggered large-scale crustal melting and generated mixed-origin silicic melts. Suchrapid formation of silicic magmas from sustained basaltic volcanism may serve as an analogue for generatingcontinental crust in a subduction–free early Earth (e.g. ≥ 3 Ga, Kamber et al., 2005).

    REFERENCES:Bindeman, I.N., et al., 2012. Terra Nova 24, 227–232.Gústafsson, L.E., et al., 1989. Jökull, v. 39, 75–89.Gústafsson, L.E., 1992. PhD dissertation, Freie Universität Berlin.Jonasson, K., 2007. Journal of Geodynamics, 43, 101–117.Kamber, B.S., et al., 2005. Earth Planet. Sci. Lett., Vol. 240 (2), 276-290.Martin, E., et al., 2011. Earth Planet. Sc. Lett., 311, 28–38.Óskarsson, B.V., & Riishuus, M.S., 2013. J. Volcanol. Geoth.Res., 267, 92–118.Walker, G.P.L., 1966. Bull. Volcanol., 29 (1), 375-402.

  • 14.
    Berg, Sylvia
    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.
    Riishuus, M.S.
    Burchardt, Steffi
    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.
    Harris, C.
    Voluminous outburst of silicic low d18O magma in NE-Iceland inferred from zircon d18O and U-Pb geochronology2013Conference paper (Other academic)
  • 15.
    Blythe, L. S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Misiti, V.
    Masotta, M
    Taddeucci, J.
    Freda, C.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Deegan, F. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, E. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Viscosity controlled magma-carbonate interaction: a comparison of Mt. Vesuvius (Italy) and Mt. Merapi (Indonesia)2012Conference paper (Refereed)
    Abstract [en]

    Magma-carbonate interaction is increasingly seen as a viable and extremely important cause of magma contamination, and the generation of a crustally sourced CO2 phase (Goff et al., 2001; Freda et al., 2010). Even though the process is well recognized at certain volcanoes e.g. Popocatépetl, (Mexico); Merapi, (Indonesia); and Colli Albani, (Italy) (Goff et al., 2001; Deegan et al., 2010; Freda et al., 2010), neither the kinetics of carbonate assimilation nor its consequences for controlling the explosivity of eruptions have been constrained. Here we show the results of magma-carbonate interaction experiments conducted at 1200 °C and 0.5 GPa for varying durations (0 s, 60 s, 90 s and 300 s) for the Mt. Merapi (Indonesia) and Mt. Vesuvius (Italy) volcanic systems. We performed experiments using glassy starting materials specific to each volcano (shoshonite for Mt. Vesuvius, basaltic-andesite for Mt. Merapi) with different degrees of hydration (anhydrous vs hydration with ~ 2 wt % water) and using carbonate fragments of local origin; see Deegan et al., (2010) and Jolis et al., (2011). Experimental products include a gas phase (CO2-rich) and two melt phases, one pristine (Ca-normal) and one contaminated (Ca-rich) separated by a 'contamination front' which propagates outwards from the carbonate clast. Vesicles appear to nucleate in the contaminated glass and then migrate into the pristine one. Both contamination front propagation and bubble migration away from the carbonate are slower in anhydrous basaltic-andesite (Merapi anhydrous series) than in hydrated basaltic-andesite and shoshonite (Merapi and Vesuvius hydrated series), suggesting that assimilation speed is strongly controlled by the degree of hydration and the SiO2 content, both of which influence melt viscosity and hence diffusivity. As the carbonate dissolution proceeds in our experiments, initially dissolved and eventually exsolved CO2 builds up in the contaminated Ca-rich melt phase. Once melt volatile oversaturation is achieved, the reaction can only progress further if vesicles are efficiently removed from the contaminated melt phase. Viscosity, which controls the vesicle migration efficiency, thus ultimately determines the progression and rate of the contamination reaction. Our results show that characteristics of magma-carbonate interaction at different volcanic systems are likely to differ as a result of a volcanos' individual magma properties, especially viscosity, which determines the speed at which gaseous reaction products (i.e. CO2) can be removed from the reaction site.

  • 16.
    Blythe, L. S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Hilton, D.R.
    Deegan, F. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Jolis, E. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Stimac, J
    Chadwick, J. P.
    Chew, D.
    Magmatic vs crustal volatiles: a reconnaissance tool for geothermal energy2012Conference paper (Refereed)
  • 17.
    Blythe, Lara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology. School of Physical and Geographical Science, Keele University, Keele, UK.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Freda, C
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    Jolis, Ester Muños
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Masotta, M
    Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany.
    Misiti, V.
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    Taddeucci, J.
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    CO2 bubble generation and migration during magma–carbonate interaction2015In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 169, no 4, article id 42Article in journal (Refereed)
    Abstract [en]

    We conducted quantitative textural analysis of vesicles in high temperature and pressure carbonate assimilation experiments (1200 °C, 0.5 GPa) to investigate CO2 generation and subsequent bubble migration from carbonate into magma. We employed Mt. Merapi (Indonesia) and Mt. Vesuvius (Italy) compositions as magmatic starting materials and present three experimental series using (1) a dry basaltic-andesite, (2) a hydrous basaltic-andesite (2 wt% H2O), and (3) a hydrous shoshonite (2 wt% H2O). The duration of the experiments was varied from 0 to 300 s, and carbonate assimilation produced a CO2-rich fluid and CaO-enriched melts in all cases. The rate of carbonate assimilation, however, changed as a function of melt viscosity, which affected the 2D vesicle number, vesicle volume, and vesicle size distribution within each experiment. Relatively low-viscosity melts (i.e. Vesuvius experiments) facilitated efficient removal of bubbles from the reaction site. This allowed carbonate assimilation to continue unhindered and large volumes of CO2 to be liberated, a scenario thought to fuel sustained CO2-driven eruptions at the surface. Conversely, at higher viscosity (i.e. Merapi experiments), bubble migration became progressively inhibited and bubble concentration at the reaction site caused localised volatile over-pressure that can eventually trigger short-lived explosive outbursts. Melt viscosity therefore exerts a fundamental control on carbonate assimilation rates and, by consequence, the style of CO2-fuelled eruptions.

  • 18.
    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.

  • 19.
    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 R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Ist Nazl Geofis & Vulcanol, Rome, Italy.
    Deegan, Frances M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden.
    Jolis, Ester
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Smith, Victoria
    Research Laboratory for Archaeology and the History of Art, University of Oxford, Oxford, UK.
    Whitehouse, Martin
    Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, South Africa.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy.
    Hilton, David
    Scripps Institution of Oceanography, University of California, San Diego, USA.
    Halldórsson, Sæmundur
    Scripps Institution of Oceanography, University of California, San Diego, USA; Univ Iceland, Inst Earth Sci, Reykjavik, Iceland.
    Bindeman, Ilya
    Department of Geological Sciences, University of Oregon, Oregon, USA.
    Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 40624Article in journal (Refereed)
    Abstract [en]

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  • 20.
    Budd, David A.
    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.
    Hilton, D.R.
    Scripps Institution of Oceanography, University of California San Diego, California, USA.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Roma, Italy.
    Jolis, Ester M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Halldorsson, S.A.
    Scripps Institution of Oceanography, University of California San Diego, California, USA.
    Traversing nature's danger zone: getting up close with Sumatra's volcanoes2012In: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 28, no 2, p. 64-70Article in journal (Refereed)
    Abstract [en]

    The Indonesian island of Sumatra, located in one of the most active zones of the Pacific Ring of Fire, is characterized by a chain of subduction-zone volcanoes which extend the entire length of the island. As a group of volcanic geochemists, we embarked upon a five-week sampling expedition to these exotic, remote, and in part explosive volcanoes (SAGE 2010; Sumatran Arc Geochemical Expedition). We set out to collect rock and gas samples from 17 volcanic centres from the Sumatran segment of the Sunda arc system, with the aim of obtaining a regionally significant sample set that will allow quantification of the respective roles of mantle versus crustal sources to magma genesis along the strike of the arc. Here we document our geological journey through Sumatra's unpredictable terrain, including the many challenges faced when working on active volcanoes in pristine tropical climes.

  • 21.
    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)
  • 22.
    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)
  • 23.
    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.
    Jolis, Ester Muños
    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.
    Toba super-eruption fuelled by catastrophic roof disintegration2014Conference paper (Refereed)
  • 24.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Tanner, David C.
    Leibniz Institute for Applied Geophysics, Hannover, Germany.
    Troll, Valentin R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, Michael
    Geoscience Center, Georg-August University Göttingen, Göttingen, Germany.
    Gustafsson, Ludvik E.
    Association of Local Authorities in Iceland, Reykjavik, Iceland.
    Three-dimensional geometry of concentric intrusive sheet swarms in the Geitafell and the Dyrfjoll volcanoes, eastern Iceland2011In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 12, no 7, p. Q0AB09-Article in journal (Refereed)
    Abstract [en]

    Sheet intrusions (inclined sheets and dykes) in the deeply eroded volcanoes of Geitafell and Dyrfjoll, eastern Iceland, were studied at the surface to identify the location, depth, and size of their magmatic source(s). For this purpose, the measured orientations of inclined sheets were projected in three dimensions to produce models of sheet swarm geometries. For the Geitafell Volcano, the majority of sheets converge toward a common focal area with a diameter of at least 4 to 7 km, the location of which coincides with several gabbro bodies exposed at the surface. Assuming that these gabbros represent part of the magma chamber feeding the inclined sheets, a source depth of 2 to 4 km below the paleoland surface is derived. A second, younger swarm of steeply dipping sheets crosscuts this gabbro and members of the first swarm. The source of this second swarm is estimated to be located to the SE of the source of Swarm 1, below the present-day level of exposure and deeper than the source of the first swarm. For the Dyrfjoll Volcano, we show that the sheets can be divided into seven different subsets, three of which can be interpreted as swarms. The most prominent swarm, the Njardvik Sheet Swarm, converges toward a several kilometers wide area in the Njardvik Valley at a depth of 1.5 to 4 km below the paleoland surface. Two additional magmatic sources are postulated to be located to the northeast and southwest of the main source. Crosscutting relationships indicate contemporaneous, as well as successive activity of different magma chambers, but without a resolvable spatial trend. The Dyrfjoll Volcano is thus part of a complex volcanic cluster that extends far beyond the study area and can serve as fossil analog for nested volcanoes such as Askja, whereas in Geitafell, the sheet swarms seem to have originated from a single focus at one time, thus defining a single central volcanic complex, such as Krafla Volcano.

  • 25.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Tanner, David C.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, Michael
    Gustafsson, Ludvik E.
    Three-dimensional geometry of concentric intrusive sheet swarms in the Geitafell and the Dyrfjöll Volcanoes, Eastern Iceland2011In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 12, no 7, p. Q0AB09-Article in journal (Refereed)
    Abstract [en]

    Sheet intrusions (inclined sheets and dykes) in the deeply eroded volcanoes of Geitafell and Dyrfjöll,eastern Iceland, were studied at the surface to identify the location, depth, and size of their magmaticsource(s). For this purpose, the measured orientations of inclined sheets were projected in three dimensionsto produce models of sheet swarm geometries. For the Geitafell Volcano, the majority of sheetsconverge toward a common focal area with a diameter of at least 4 to 7 km, the location of which coincideswith several gabbro bodies exposed at the surface. Assuming that these gabbros represent part of the magmachamber feeding the inclined sheets, a source depth of 2 to 4 km below the paleoland surface is derived.A second, younger swarm of steeply dipping sheets crosscuts this gabbro and members of the first swarm.The source of this second swarm is estimated to be located to the SE of the source of Swarm 1, below thepresent‐day level of exposure and deeper than the source of the first swarm. For the Dyrfjöll Volcano,we show that the sheets can be divided into seven different subsets, three of which can be interpretedas swarms. The most prominent swarm, the Njardvik Sheet Swarm, converges toward a several kilometerswide area in the Njardvik Valley at a depth of 1.5 to 4 km below the paleoland surface. Two additionalmagmatic sources are postulated to be located to the northeast and southwest of the main source. Crosscuttingrelationships indicate contemporaneous, as well as successive activity of different magma chambers,but without a resolvable spatial trend. The Dyrfjöll Volcano is thus part of a complex volcanic cluster thatextends far beyond the study area and can serve as fossil analog for nested volcanoes such as Askja, whereasin Geitafell, the sheet swarms seem to have originated from a single focus at one time, thus defining a singlecentral volcanic complex, such as Krafla Volcano.

  • 26.
    Burchardt, Steffi
    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.
    Mathieu, L.
    Donaldson, C.H.
    3 or 1? 3D cone-sheet architecture provides insight into the centre(s) of Ardnamurchan2013Conference paper (Refereed)
    Abstract [en]

    The Palaeogene Ardnamurchan igneous centre, NW Scotland, was a defining place for the development of classic concepts of cone-sheet, ring-dyke, and dyke emplacement. It holds therefore an iconic status among geologists and has influenced our understanding of subvolcanic structures fundamentally. We have used historic geological maps ofArdnamurchan to project the underlying three-dimensional (3D) cone-sheet structure. The results illustrate that a single elongate magma chamber likely acted as the source of the cone-sheet swarms, instead of the traditionally accepted model of three successive centres. Our finding is moreover consistent with recent sedimentological, geochemical, geophysical, and structural investigations that all support a ridge-like morphology for the Ardnamurchan volcano. This challenges the static model of cone-sheet emplacement that involves successive but independent centres in favour of a dynamical one that involves a single, but elongate magma chamber that is progressively evolving. The latter model reduces the lifetime required for the Ardnamurchan centre considerably.

  • 27.
    Burchardt, Steffi
    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.
    Mathieu, Lucie
    Emeleus, Henry C.
    Donaldson, Colin H.
    Ardnamurchan 3D cone-sheet architecture explained by a single elongate magma chamber2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, p. 2891-Article in journal (Refereed)
    Abstract [en]

    The Palaeogene Ardnamurchan central igneous complex, NW Scotland, was a defining place for the development of the classic concepts of cone-sheet and ring-dyke emplacement and has thus fundamentally influenced our thinking on subvolcanic structures. We have used the available structural information on Ardnamurchan to project the underlying three-dimensional (3D) cone-sheet structure. Here we show that a single elongate magma chamber likely acted as the source of the cone-sheet swarm(s) instead of the traditionally accepted model of three successive centres. This proposal is supported by the ridge-like morphology of the Ardnamurchan volcano and is consistent with the depth and elongation of the gravity anomaly underlying the peninsula. Our model challenges the traditional model of cone-sheet emplacement at Ardnamurchan that involves successive but independent centres in favour of a more dynamical one that involves a single, but elongate and progressively evolving magma chamber system.

  • 28.
    Burchardt, Steffi
    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.
    Schmeling, Harro
    Goethe Univ Frankfurt, Fac Earth Sci, Altenhoferallee 1, D-60438 Frankfurt, Germany..
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Erupted frothy xenoliths may explain lack of country-rock fragments in plutons2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 34566Article in journal (Refereed)
    Abstract [en]

    Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as "xenolith graveyards", or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of stoping. Here, we present new evidence that may explain the absence of abundant country-rock fragments in plutons. We report on vesiculated crustal xenoliths in volcanic rocks that experienced devolatilisation during heating and partial melting when entrained in magma. We hypothesise that the consequential inflation and density decrease of the xenoliths allowed them to rise and become erupted instead of being preserved in the plutonic record. Our thermomechanical simulations of this process demonstrate that early-stage xenolith sinking can be followed by the rise of a heated, partially-molten xenolith towards the top of the reservoir. There, remnants may disintegrate and mix with resident magma or erupt. Shallow-crustal plutons emplaced into hydrous country rocks may therefore not necessarily contain evidence of the true amount of magmatic stoping during their emplacement. Further studies are needed to quantify the importance of frothy xenolith in removing stoped material.

  • 29.
    Burchardt, Steffi
    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.
    Schmeling, Harro
    Faculty of Earth Sciences, J. W. Goethe Universität, Altenhöferallee 1, 60438 Frankfurt am Main, Germany.
    Koyi, Hemin
    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.
    Sink or swim: The fate of crustal xenoliths in shallow magma chambersIn: Article in journal (Other academic)
  • 30. Byrne, P.
    et al.
    Holohan, E
    Kervyn, M
    van Wyk de Vries, B.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Analogue modelling of volcano flank terrace formation on Mars2015In: Volcanism and Tectonism Across the Inner Solar System / [ed] Platz, T., Massironi M., Byrne P.K. and Hisinger H., Geological Society of London, 2015Chapter in book (Refereed)
    Abstract [en]

    Of the features that characterize large shield volcanoes on Mars, flank terraces remain the most enigmatic. Several competing mechanisms have been proposed for these laterally expansive, topographically subtle landforms. Here we test the hypothesis that horizontal contraction of a volcano in response to the down-flexing of its underlying basement leads to flank terracing. We performed a series of analogue models consisting of a conical sand–plaster load emplaced on a basement comprising a layer of brittle sand–plaster atop a reservoir of viscoelastic silicone. Our experiments consistently produced a suite of structures that included a zone of concentric extension distal to the conical load, a flexural trough adjacent to the load base and convexities (terraces) on the cone's flanks. The effects of variations in the thickness of the brittle basal layer, as well as in the volume, slope and planform eccentricity of the cone, were also investigated. For a given cone geometry, we find that terrace formation is enhanced as the brittle basement thickness decreases, but that a sufficiently thick brittle layer can enhance the basement's resistance to loading such that terracing of the cone is reduced or even inhibited altogether. For a given brittle basement thickness, terracing is reduced with decreasing cone slope and/or volume. Our experimental results compare well morphologically to observations of terraced edifices on Mars, and so provide a framework with which to understand the developmental history of large shield volcanoes on the Red Planet.

  • 31. Byrne, P. K.
    et al.
    Holohan, E. P.
    Kervyn, M.
    de Vries, B. van Wyk
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Murray, J. B.
    A sagging-spreading continuum of large volcano structure2013In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 41, no 3, p. 339-342Article in journal (Refereed)
    Abstract [en]

    Gravitational deformation strongly influences the structure and eruptive behavior of large volcanoes. Using scaled analog models, we characterize a range of structural architectures produced by volcano sagging and volcano spreading. These arise from the interplay of variable basement rigidity and volcano-basement (de-)coupling. From comparison to volcanoes on Earth (La Reunion and Hawaii) and Mars (Elysium and Olympus Montes), the models highlight a structural continuum in which large volcanoes throughout the Solar System lie.

  • 32. Byrne, Paul K.
    et al.
    de Vries, Benjamin van Wyk
    Murray, John B.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    The geometry of volcano flank terraces on Mars2009In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 281, no 1-2, p. 1-13Article in journal (Refereed)
    Abstract [en]

    Flank terraces are subtle, expansive structures on the slopes of many large Martian shield volcanoes. Several terrace formation hypotheses - including self-loading, lithospheric flexure, magma chamber tumescence, volcano spreading, and shallow gravitational slumping - have been suggested. Terraces are not readily visible on photogeological data; consequently, terrace geometry has not yet been comprehensively described. Terrace provenance, therefore, is poorly understood. We used three-dimensional Mars Orbiter Laser Altimeter (MOLA) data to characterise the geometry of these elusive structures, with a view to   understanding better the role that flank terraces play in the tectonic evolution of volcanoes on Mars. Terraces have a broad, convex-upward profile in section, and a systematic "fish scale" imbricate stacking pattern in plan. They are visible at all elevations, on at least nine   disparate Martian volcanoes. Terrace-like features also occur on three shield volcanoes on Earth, an observation not recorded before. Analysis of a suite of morphometric parameters for flank terraces showed that they are scale-invariant. with similar proportions to thrust faults on Earth. We compared predicted formation geometries to our terrace observations, and found that only lithospheric flexure can fully account for the morphology, distribution, and timing of terraces. As a volcano flexes into the lithosphere beneath it, its upper surface will  experience a net reduction in area, resulting in the formation of outward verging thrusts. We conclude, therefore, that flank terraces are fundamental volcanotectonic structures, that they are the surface expressions of thrust faults, probably formed by lithospheric flexure. and that they are not restricted to Mars.

  • 33. Byrne, P.K.
    et al.
    Holohan, E.P.
    Kervyn, M.
    van Wyk de Vries, B.
    Murray, J.B.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    A Sagging-Spreading Continuum for the Structure of Large Volcanoes on Terrestrial Planets2011Conference paper (Other academic)
  • 34. Byrne, P.K.
    et al.
    Van Wyk de Vries, B.
    Murray, J.B.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    A Volcanotectonic Survey of Ascraeus Mons, Mars2011In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117Article in journal (Refereed)
    Abstract [en]

    Ascraeus Mons is one of the largest volcanoes on Mars. It is replete with well-preserved features that can be used to understand its volcanotectonic evolution. Previous studies of this volcano focused on specific features, and were limited by the quality and coverage of contemporary data. Our objective is to review and enhance the existing developmental model for Ascraeus by considering all endogenic surface features on the volcano. We surveyed the volcano's caldera complex, flank terraces, pit structures, sinuous rilles, arcuate grabens, and small vents. We report the spatial and temporal distributions of these features, appraise their proposed formation mechanisms in light of our mapping results, and propose a detailed geological history for Ascraeus Mons. An initial shield-building phase was followed by the formation of a summit caldera complex and small parasitic cones, while compression due to flexure of the supporting basement led to extensive terracing of the shield flanks. An eruptive hiatus followed, ending with the construction of expansive rift aprons to the northeast and southwest. Against later, extensive flank resurfacing in the late Amazonian, continued flexure formed arcuate grabens concentric to the edifice. Localized eruption and surface flow of a fluid agent (lava and/or water) from within the volcano then produced a population of rilles on the lower flanks. Finally, in a change of flank tectonic regime from compression to extension, pit crater chains and troughs developed on the main shield and rift aprons, eventually coalescing to form large embayments at the northeast and southwest base of the volcano.

  • 35. Carracedo, J. C.
    et al.
    Fernandez-Turiel, J. L.
    Gimeno, D.
    Guillou, H.
    Kluegel, A.
    Krastel, S.
    Paris, R.
    Perez-Torrado, F. J.
    Rodriguez-Badiola, E.
    Rodriguez-Gonzalez, A.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Walter, T. R.
    Wiesmaier, S.
    Comment on "The distribution of basaltic volcanism on Tenerife, Canary Islands: Implications on the origin and dynamics of the rift systems" by A. Geyer and J. Marti. Tectonophysics 483 (2010) 310-3262011In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 503, no 3-4, p. 239-241Article in journal (Other academic)
  • 36. Carracedo, J. C.
    et al.
    Guillou, H.
    Nomade, S.
    Rodriguez-Badiola, E.
    Perez-Torrado, F. J.
    Rodriguez-Gonzalez, A.
    Paris, R.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, S.
    Delcamp, A.
    Fernandez-Turiel, J. L.
    Evolution of ocean-island rifts: The northeast rift zone of Tenerife, Canary Islands2011In: Geological Society of America Bulletin, ISSN 0016-7606, E-ISSN 1943-2674, Vol. 123, no 3-4, p. 562-584Article in journal (Refereed)
    Abstract [en]

    The northeast rift zone of Tenerife presents a superb opportunity to study the entire cycle of activity of an oceanic rift zone. Field geology, isotopic dating, and magnetic stratigraphy provide a reliable temporal and spatial framework for the evolution of the NE rift zone, which includes a period of very fast growth toward instability (between ca. 1.1 and 0.83 Ma) followed by three successive large landslides: the Micheque and Guimar collapses, which occurred approximately contemporaneously at ca. 830 ka and on either side of the rift, and the La Orotava landslide (between 690 +/- 10 and 566 +/- 13 ka). Our observations suggest that Canarian rift zones show similar patterns of development, which often includes overgrowth, instability, and lateral collapses. Collapses of the rift flanks disrupt established fissural feeding systems, favoring magma ascent and shallow emplacement, which in turn leads to magma differentiation and intermediate to felsic nested eruptions. Rifts and their collapses may therefore act as an important factor in providing architectural and petrological variability to oceanic volcanoes. Conversely, the presence of substantial felsic volcanism in rift settings may indicate the presence of earlier landslide scars, even if concealed by postcollapse volcanism. Comparative analysis of the main rifts in the Canary Islands outlines this general evolutionary pattern: (1) growth of an increasingly high and steep ridge by concentrated basaltic fissure eruptions; (2) flank collapse and catastrophic disruption of the established feeder system of the rift; (3) postcollapse centralized nested volcanism, commonly evolving from initially ultramafic-mafic to terminal felsic compositions (trachytes, phonolites); and (4) progressive decline of nested eruptive activity.

  • 37. Carracedo, J.C.
    et al.
    Guillou, H.
    Badiola, E. Rodriguez,
    Perez-Torrado, F.J.
    Gonzalez, A. Rodriguez
    Paris, R.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, S.
    Delcamp, A.
    Rernandez-Turiel, J.L
    The NE Rift of Tenerife: towards a model on the origin and evolution of ocean island rifts2009In: Estudios Geologicos, Vol. 65, no 1, p. 5-47Article in journal (Refereed)
    Abstract [en]

    The NE Rift of Tenerife is an excellent example of a persistent, recurrent rift, providing important evidence of the origin and dynamics   of these major volcanic features. The rift developed in three  successive, intense and relatively short eruptive stages (a few hundred   ka), separated by longer periods of quiescence or reduced activity: A  Miocene stage (7266 +/- 156 ka), apparently extending the central Miocene shield of Tenerife towards the Anaga massif; an Upper Pliocene   stage (2710 +/- 58 ka) and the latest stage, with the main eruptive   phase in the Pleistocene. Detailed geological (GIS) mapping, geomagnetic reversal mapping and stratigraphic correlation, and radioisotopic (K/Ar) dating of volcanic   formations allowed the reconstruction of the latest period of rift   activity. In the early phases of this stage the majority of the   eruptions grouped tightly along the axis of the rift and show reverse polarity (corresponding to the Matuyama chron). Dykes are of normal and   reverse polarities. In the final phase of activity, eruptions are more   disperse and lavas and dykes are consistently of normal polarity   (Brunhes chron). Volcanic units of normal polarity crossed by dykes of   normal and reverse polarities yield ages apparently compatible with   normal subchrons (M-B Precursor and Jaramillo) in the Upper Matuyama   chron. Three lateral collapses successively mass-wasted the rift: The   Micheque collapse, completely concealed by subsequent nested volcanism,   and the Guimar and La Orotava collapses, that are only partially   filled. Time occurrence of collapses in the NE rift apparently   coincides with glacial stages, suggesting that giant landslides may be   finally triggered by sea level changes during glaciations. Pre-collapse   and nested volcanism is predominantly basaltic, except in the Micheque   collapse, where magmas evolved towards intermediate and felsic   (trachytic) compositions.   Rifts in the Canary Islands are long-lasting, recurrent features,   probably related to primordial, plume-related fractures acting   throughout the entire growth of the islands. Basaltic volcanism forms   the bulk of the islands and rift zones. However, collapses of the   flanks of the rifts disrupt their established fissural feeding system,   frequently favouring magma accumulation and residence at shallow   emplacements, leading to differentiation of magmas, and intermediate to felsic nested eruptions. Rifts and their collapse may therefore act as an important factor in providing petrological variability to oceanic   volcanoes. Conversely, the possibility exists that the presence of  important felsic volcanism may indicate lateral collapses in oceanic shields and ridge-like volcanoes, even if they are concealed by post-collapse volcanism or partially mass-wasted by erosion.

  • 38.
    Carracedo, J.C.
    et al.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Pérez-Torrado, F.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Rodríguez-González, A.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Klügel, A.
    Universität Bremen, Bremen, Germany.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmeier, S.
    Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany.
    The Ongoing Volcanic Eruption of El Hierro, Canary Islands2012In: Transaction of the American Geophysical Union, EOS, Vol. 93, p. 89-90Article in journal (Other academic)
    Abstract [en]

    El Hierro, the youngest of the Canary Islands (Spain), is no stranger to hazards associated with volcanic activity or to efforts to minimize the effects of these hazards on local communities. As early as 1793, administrative records of El Hierro indicate that a swarm of earthquakes was felt by locals; fearing a greater volcanic catastrophe, the first evacuation plan of an entire island in the history of the Canaries was prepared. The 1793 eruption was probably submarine with no appreciable consequences other than that the earthquakes were felt [Carracedo, 2008]; over the next roughly 215 years the island was seismically quiet. Yet seismic and volcanic activity are expected on this youngest Canary Island due to its being directly above the presumed location of the Canary Island hot spot, a mantle plume that feeds upwelling magma just under the surface, similar to the Hawaiian Islands. Because of this known geologic activity, the Spanish Instituto Geográfco Nacional (IGN) has managed geophysical monitoring of the island since the beginning of the 1990s.

  • 39.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Pérez-Torrado, Francisco José
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Rodríguez González, Alejandro
    Grupo de Investigación GEOVOL, Dpto. de Física, Universidad de Las Palmas de Gran Canaria, Spain .
    Soler, Vicente
    Estación Volcanológica de Canarias, IPNA‐CSIC, La Laguna, Tenerife, Spain.
    Fernández Turiel, José Luis
    Instituto de Ciencias de la Tierra Jaume Almera, CSIC, Barcelona, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Wiesmaier, Sebastian
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    The 2011 submarine volcanic eruption in El Hierro (Canary Islands)2012In: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 28, no 2, p. 53-58Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Forty years after the Teneguía Volcano (La Palma, 1971), a submarine eruption took place off the town of La Restinga, south of El Hierro, the smallest and youngest island of the Canarian Archipelago. Precursors allowed an early detection of the event and its approximate location, suggesting it was submarine. Uncertainties derived from insufficient scientific information available to the authorities during the eruption, leading to disproportionate civil protection measures, which had an impact on the island's economy—based primarily on tourism—while residents experienced extra fear and distress.

  • 40.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Rodriguez-Gonzalez, Alejandro
    Pérez-Torrado, Francisco José
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Fernandez-Turiel, J-L.
    Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Barcelona, Spain.
    Paris, Raphaël
    Université Blaise Pascal, UMR 6524, Clermont-Ferrand & CNRS, France.
    Rodríguez-Badiola, E.
    Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.
    Pestana-Pérez, G.
    Consejería de Agricultura, Ganadería, Pesca y Alimentación, Gobierno de Canarias, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, Sebastian
    Departamento de Física (GEOVOL), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary, Islands, Spain.
    Geological Hazards in the Teide Volcanic Complex2013In: Teide Volcano: Geology and Eruptions of a Highly Differentiated Oceanic Stratovolcano, Springer Berlin/Heidelberg, 2013, p. 249-272Chapter in book (Refereed)
    Abstract [en]

    The island of Tenerife displays contrasted densities of population, from the densely occupied coastal zones (including tourist resorts, airport, energy facilities, etc.) to the sparsely populated forests and mountainous highlands, where most of the recent volcanic events are located. Considering the low frequency of historical eruptions (compared to Hawaii or Reunion Island for example), the assessment of geological hazards must also rely on the analysis and interpretation of prehistorical events, going back to at least the Late Quaternary. In this chapter, we review the hazards related to Teide’s volcanism, but also those from increased seismicity and from slope instability. We discuss the origin of low magnitude earthquakes, and particularly the 2004 episode of unrest. New estimates on cumulative volumes for resurfacing by lava flows during the last few thousand years are provided to serve as a tool for building a lava flow hazard map of Tenerife. Hazards related to explosive activity are also considered and although possible, with phreatomagmatic eruptions being the most likely style anticipated, explosive events are of relatively low probability at Teide in the near future.

  • 41.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    From Myth to Science: The Contribution of Mount Teide to the Advancement of Volcanology2013In: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, p. 1-21Chapter in book (Refereed)
    Abstract [en]

    This chapter outlines the progress of geological research into the origin and evolution of the Teide Volcanic Complex within the framework of Tenerife Island, the Canary Islands, and oceanic volcanism in general. Initially considered to relate to either the entrance to ‘Hell’ or to mythical Atlantis, for von Buch, von Humboldt, Lyell and the other great eighteenth and nineteenth century naturalists Teide eventually helped to shape a new, and at that time revolutionary concept; the origin of volcanic rocks from solidified magma. This school of thought slowly cast aside Neptunism and removed some of the last barriers for the development of modern Geology and Volcanology as the sciences we know today. Despite the volcanic nature of the Canaries having been already recognised by the twentieth century, modern geological understanding of the archipelago progressed most significantly with the advent of plate tectonics. While some authors still maintain a link between the Canaries and the Atlas tectonic regime (see also Chap.​ 2), geological research truly advanced in the Canaries through comparison with hotspot-derived archipelagos, particularly the Hawaiian Islands. This approach, initiated in the 1970s, provided a breakthrough in the understanding of Canary volcanism, demonstrating Tenerife and Teide to be one of the world’s most interesting, complex and to many, one of the most iconic of oceanic volcanoes.

  • 42.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Structural and Geological Elements of Teide Volcanic Complex: Rift Zones and Gravitational Collapses2013In: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer, 2013, p. 57-74Chapter in book (Refereed)
    Abstract [en]

    Initially recognised in the Hawaiian Islands, volcanic rift zones and associated giant landslides have been extensively studied in the Canaries, where several of their more significant structural and genetic elements have been established. Almost 3,000 km of water tunnels (galerías) that exist in the western Canaries provide a unique possibility to access the deep structure of the island edifices. Recent work shows that rift zones to control the construction of the islands, possibly from the initial stages of island development, form the main relief features (shape and topography), and concentrate eruptive activity, making them crucial elements in defining the distribution of volcanic hazards on ocean islands.

  • 43.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, ValentinUppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Teide Volcano: Geology and Eruptions of a Highly Differentiated Oceanic Stratovolcano2013Collection (editor) (Other academic)
    Abstract [en]

    Teide Volcano has many different meanings: For the Guanche aborigines, who endured several of its eruptions, it was Echeide (Hell). Early navigators had in Teide, a lifesaving widely visible landmark that was towering over the clouds. For the first explorers, Teide was a challenging and dangerous climb, since it was thought that Teide's peak was so high that from its summit the sun was too close and far too hot to survive. Teide was considered the highest mountain in the world at that time and measuring its height precisely was a great undertaking and at the time of global scientific significance. For von Buch, von Humboldt, Lyell and other great 18th and19th century naturalists, Teide helped to shape a new and now increasingly 'volcanic' picture, where the origin of volcanic rocks (from solidified magma) slowly casted aside Neptunism and removed some of the last barriers for the development of modern Geology and Volcanology as the sciences we know today. For the present day population of Tenerife, living on top of the world's third tallest volcanic structure on the planet, Teide has actually become "Padre Teide", a fatherly protector and an emblematic icon of Tenerife, not to say of the Canaries as a whole. The UNESCO acknowledged this iconic and complex volcano, as "of global importance in providing evidence of the geological processes that underpin the evolution of oceanic islands". Today, 'Teide National Park' boasts 4 Million annual visitors including many 'volcano spotters' and is a spectacular natural environment which most keep as an impression to treasure and to never forget. For us, the editors of this book, Teide is all of the above; a 'hell of a job', a navigation point on cloudy days, a challenge beyond imagination, a breakthrough in our understanding of oceanic volcanism that has shaped our way of thinking about volcanoes, and lastly, Teide provides us with a reference point from where to start exploring other oceanic volcanoes in the Canaries and beyond. Here we have compiled the different aspects and the current understanding of this natural wonder.

  • 44.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    The Geology of the Canary Islands2016Book (Other academic)
  • 45.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Department of Geology, Trinity College, Dublin.
    Pérez-Torrado, Francisco José
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Hansen, Alex
    Departamento Geología, Universidad de Las Palmas de Gran Canaria, Spain.
    Rodriguez-Badiola, Eduardo
    Museo Nacional de Ciencias Naturales, CSIC, Madrid.
    Paris, Raphael
    Maison de la Recherche, CNRS, Clermont-Ferrand, France.
    Guillou, Hervé
    Laboratoire des Sciences du Climat et de l'Environnement, CNRS, Gif-sur-Yvette, France.
    Scaillet, Stéphane
    Laboratoire des Sciences du Climat et de l'Environnement, CNRS, Gif-sur-Yvette, France.
    Reply to Comment on “Recent unrest at Canary Islands' Teide Volcano?”2007In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 88, no 46, p. 488-Article in journal (Other academic)
    Abstract [en]

    Small-magnitude seismic episodes unrelated to a volcanic eruption have been a relatively frequent feature in all the Canaries without causing any significant public alarm. Conversely, great alarm was raised in May 2004 in Tenerife, when apparently numerous low-magnitude seismic signals were recorded, although only a few of them were actually felt in nearby villages.

    Public alarm was raised by (1) the publication on a Web site of imperceptible seismic signals as low as 0.6 on the Richter scale, most of which were not even adequately localized and yet were reproduced almost daily in the local and national press without further comment or explanation; (2) a Spanish national scientific committee being replaced by a local committee that was scientifically advised by a private company; and (3) publicity given by the media to the prediction made by members of the local committee of a potentially large scale explosive eruption in October 2004 (dubbed “the October volcano” by residents). Interestingly, obvious fumarole activity was absent in autumn 2004 during an inspection of Teide summit by three of us.

  • 46. Carracedo, Juan Carlos
    et al.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Zaczek, Kirsten
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Rodriguez-Gonzales, Alejandro
    Soler, Vincente
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    The 2011-2012 submarine eruption off El Hierro, Canary Islands: New lessons in oceanic island growth and volcanic crisis management2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 150, p. 168-200Article in journal (Refereed)
    Abstract [en]

    Forty years after the eruption of the Teneguía volcano on La Palma, 1971, the last volcanic event in the Canary Islands, a submarine eruption took place in 2011 off-shore El Hierro, the smallest and youngest island of the archipelago. In this paper, we review the periods of seismic unrest leading up to the 2011–2012 El Hierro eruption, the timeline of eruptive events, the erupted products, the wider societal impacts, and the insights garnered for our understanding of ocean island growth mechanisms and hazard management. Seismic precursors allowed early detection of magmatic activity and prediction of the approximate location of the eruption. White coloured “floating stones” (“xeno-pumice”) were described within the first few days of the events, the origin of which were hotly debated because of their potential implications for the character of the eruption. Due to epistemic uncertainty derived from delayed flow of scientific information and equivocal interpretations of the “floating stones”, the El Hierro 2011–2012 events were characterised by cautious civil protection measures, which greatly impacted on the residents' lives and on the island's economy. We therefore summarise the scientific lessons learned from this most recent Canary Island eruption and discuss how emergency managers might cope with similar situations of uncertainty during future eruptive events in the region.

  • 47.
    Carracedo, Juan-Carlos
    et al.
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Perez-Torrado, Francisco J.
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Rodriguez-Gonzalez, Alejandro
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Paris, Raphael
    Université Blaise Pascal Clermont-Ferrand II, France.
    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.
    Volcanic and structural evolution of Pico do Fogo, Cape Verde2015In: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, no 4, p. 146-152Article in journal (Refereed)
    Abstract [en]

    In recent months the media have drawn attention to the Cape Verde archipelago, with particular focus on the island of Fogo, the only island presently active and with an eruption that began on 23 November 2014, finally ceasing on 7 February 2015. The Monte Amarelo conical shield forms most of the 476 km2 almost circular island of Fogo. After attaining a critical elevation of about 3500 m, the Monte Amarelo shield volcano was decapitated by a giant landslide that formed a caldera-like depression (Cha das Caldeiras), which was subsequently partially filled by basaltic nested volcanism. This younger eruptive activity culminated in the construction of the 2829 m-high Pico do Fogo stratocone, apparently entirely made of layers of basaltic lapilli. Continued growth of the Pico do Fogo summit eruptions was interrupted in 1750, most likely after the stratocone reached a critical height. Since then, at least eight eruptions have taken place inside the landslide depression at the periphery of the Pico do Fogo cone, including the 2014–2015 eruptive event. Strong geological similarities with the Canary Islands, 1400 km to the north, have been frequently noted, probably as a consequence of a common process of origin and evolution associated with a mantle hot-spot. These similarities are particularly evident when comparing Fogo with the Teide Volcanic Complex on Tenerife, where a lateral collapse of the Las Cañadas stratovolcano also formed a large depression (the Caldera de Las Cañadas), now partially filled with the 3718 m-high Teide stratocone. However, important geological differences also exist and probably relate to the contrasting evolutionary stages of both islands. The Las Cañadas volcano on Tenerife formed at a late post-erosional stage, with predominantly evolved (trachyte and phonolite) magmas, while at Fogo basaltic volcanism is still dominant.

  • 48.
    Cassidy, Mike
    et al.
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany.
    Castro, Jonathan
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Helo, Christoph
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Deegan, Frances M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Muir, Duncan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Neave, David
    Institute of Mineralogy, Leibniz University of Hannover, 30167 Hannover, Germany.
    Mueller, Sebastian
    Institute of Geosciences, University of Mainz, D-55122 Mainz, Germany .
    Volatile dilution during magma injections and implications for volcano explosivity2016In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 44, no 12, p. 1027-1030Article in journal (Refereed)
    Abstract [en]

    Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H2O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal scale. H2O contents within melt inclusions range from ∼0.45 to 2.27 wt% and do not correlate with melt inclusion size or distance from the crystal rim, suggesting that minimal H2O was lost via diffusion. Instead, inclusion H2O contents vary systematically with anorthite content of the host plagioclase (R2 = 0.51), whereby high anorthite content zones are associated with low H2O contents and vice versa. This relationship suggests that injections of hot and H2O-poor magma can increase the reservoir temperature, leading to the dilution of melt H2O contents. In addition to recording hot and H2O-poor conditions after these injections, plagioclase crystals also record relatively cold and H2O-rich conditions such as prior to the explosive 2014 eruption. In this case, the elevated H2O content and increased viscosity may have contributed to the high explosivity of the eruption. The point at which an eruption occurs within such repeating hot and cool cycles may therefore have important implications for explaining alternating eruptive styles.

  • 49.
    Chadwick, J.P.
    et al.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Waight, T.E.
    Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark.
    van der Zwan, F.M.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Schwarzkopf, L.M.
    GeoDocCon, Unterpferdt 8, 95176 Konradsreuth, Germany.
    Petrology and geochemistry of igneous inclusions in recent Merapi deposits: a window into the sub-volcanic plumbing system2013In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 165, no 2, p. 259-282Article in journal (Refereed)
    Abstract [en]

    Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, geochemistry and geobarometric calculations. The inclusions may be classified into four main suites: (1) highly crystalline basaltic-andesite inclusions, (2) co-magmatic enclaves, (3) plutonic crystalline inclusions and (4) amphibole megacrysts. Highly crystalline basaltic-andesite inclusions and co-magmatic enclaves typically display liquid–liquid relationships with their host rocks, indicating mixing and mingling of distinct magmas. Co-magmatic enclaves are basaltic in composition and occasionally display chilled margins, whereas highly crystalline basaltic-andesite inclusions usually lack chilling. Plutonic inclusions have variable grain sizes and occasionally possess crystal layering with a spectrum of compositions spanning from gabbro to diorite. Plagioclase, pyroxene and amphibole are the dominant phases present in both the inclusions and the host lavas. Mineral compositions of the inclusions largely overlap with compositions of minerals in recent and historic basaltic-andesites and the enclaves they contain, indicating a cognate or ‘antelithic’ nature for most of the plutonic inclusions. Many of the plutonic inclusions plot together with the host basaltic-andesites along fractional crystallisation trends from parental basalt to andesite compositions. Results for mineral geobarometry on the inclusions suggest a crystallisation history for the plutonic inclusions and the recent and historic Merapi magmas that spans the full depth of the crust, indicating a multi-chamber magma system with high amounts of semi-molten crystalline mush. There, crystallisation, crystal accumulation, magma mixing and mafic recharge take place. Comparison of the barometric results with whole rock Sr, Nd, and Pb isotope data for the inclusions suggests input of crustal material as magma ascends from depth, with a significant late addition of sedimentary material from the uppermost crust. The type of multi-chamber plumbing system envisaged contains large portions of crystal mush and provides ample opportunity to recycle the magmatic crystalline roots as well as interact with the surrounding host lithologies.

  • 50.
    Chew, David M.
    et al.
    Department of Geology, Trinity College Dublin, Dublin 2, Ireland .
    Ganerød, Morgan
    Geological Survey of Norway (NGU), Norway.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Corfu, Fernando
    Department of Geosciences, Un iversity of Oslo, Norway.
    Meade, Fiona
    Department of Geology, Trinity College Dublin, Ireland.
    U-Pb TIMS zircon age constraints on the Tardree Rhyolite zircon fission track standard2008In: On Track Forum, Vol. 16, no 1Article in journal (Other academic)
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