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  • 1.
    Abirifard, Mahmoud
    et al.
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Raeisi, Ezzat
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Zarei, Mehdi
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Zare, Mohammad
    Shiraz Univ, Coll Sci, Dept Earth Sci, Shiraz, Iran..
    Filippi, Michal
    Czech Acad Sci, Inst Geol, Vvi, Rozvojova 269, Prague 6, Czech Republic..
    Bruthans, Jiri
    Charles Univ Prague, Fac Sci, Albertov 6, Prague 12843 2, Czech Republic..
    Talbot, Christopher J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jahani Salt Diapir, Iran: hydrogeology, karst features and effect on surroundings environment2017Ingår i: International Journal of Speleology, ISSN 0392-6672, E-ISSN 1827-806X, Vol. 46, nr 3, s. 445-457Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Jahani Salt Diapir (JSD), with an area of 54 km(2), is an active diapir in the Simply Folded Belt of the Zagros Orogeny, in the south of Iran. Most of the available studies on this diapir are focused on tectonics. The hydrogeology, schematic model of flow direction and hydrochemical effects of the JSD on the adjacent water resources are lacking, and thus, are the focus of this study. The morphology of the JSD was reevaluated by fieldwork and using available maps. The physicochemical characteristics of the springs and hydrometric stations were also measured. The vent of the diapir is located 250 m higher than the surrounding glaciers, and covered by small polygonal sinkholes (dolines). The glacier is covered by cap soils, sparse trees and pastures, and contains large sinkholes, numerous shafts, several caves, and 30 brine springs. Two main groups of caves were distinguished. Sub-horizontal or inclined stream passages following the surface valleys and vertical shafts (with short inlet caves) at the bottoms of nearly circular blind valleys. Salt exposure is limited to steep slopes. The controlling variables of flow route within salt diapirs are the negligible porosity of the salt rocks at depth more than about ten meters below the ground surface and the rapid halite saturation along the flow route. These mechanisms prevent deep cave development and enforce the emergence points of brine springs with low flow rates and small catchment area throughout the JSD and above the local base of erosion. Tectonics do not affect karst development, because the distributions of sinkholes and brine springs show no preferential directions. The type of spring water is sodium chloride, with a TDS of 320 g/l, and saturated with halite, gypsum, calcite and dolomite. The water balance budget of the JSD indicates that the total recharge water is 1.46 MCM (million cubic meter)/a, emerges from 30 brine springs, two springs from the adjacent karstic limestone, and flows into the Firoozabad River (FR) and the adjacent alluvium aquifer. The FR cuts through the northern margin of the salt diapir, dissolving the glacier salts at the contact with JSD, increasing the halite concentration of the 17.7 MCM/a of the FR from 100 mg/l to 12,000 mg/l. This is a permanent process because the active glacier flows rapidly down the steep slopes into the river gorge from the nearby vent. The possible relocation of the FR channel would enhance the FR water quality, but disrupt the natural beauty of the diapir.

  • 2.
    Ahmadi, Omid
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Koyi, Hemin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Juhlin, Christopher
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Gessner, Klaus
    Geol Survey Western Australia, 100 Plain St, East Perth, WA 6004, Australia.
    Seismic signatures of complex geological structures in the Cue-Weld range area, Murchison domain, Yilgarn Craton, Western Australia2016Ingår i: Tectonophysics, Vol. 689, s. 56-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Murchison domain forms the northwest part of the Youanmi Terrane, a tectonic unit within the Neoarchean Yilgarn Craton in Western Australia. In the Cue-Weld Range area the Murchison domain has experienced a complex magmatic and deformation history that resulted in a transposed array of greenstone belts that host significant iron, gold, and base metal deposits. In this study, we interpret the upper 2 s (about 6 km) of a deep crustal seismic profile TOGA-YU1, near the town of Cue, and correlate rock units and structures in outcrop with corresponding reflections. We performed 3D constant velocity ray-tracing and calculate the corresponding travel times for the reflectionsfor time domain pre-stack and post-stack seismic data. This allows us to link shallow reflections with mafic volcanic rocks of the Glen Group and basaltic rocks of the Polelle Group in outcrop. Based on our interpretation and published geological maps and data, we propose a model in which the local stratigraphy represents a refolded thrust system. To test our hypothesis, we applied 2D acoustic finite difference forward modeling. The corresponding synthetic data were processed in the same way as the acquired data. Comparisons between the acquired and the synthetic data show that the model is consistent with observations. We propose a new model for the subsurface of the Cue-Weld Range area and argue that some of the lithologies in the area are repeated structurally at different levels. Our approach highlights the benefit of imaging and modeling of deep seismic transects to resolve local structural complexity in Archean granite-greenstone terrains.

  • 3.
    Almqvist, Bjarne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Biedermann, Andrea
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Misra, Santanu
    Petrofabric development during experimental partial melting and recrystallization of a mica-schist analogue2015Ingår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 16, nr 10, s. 3472-3483Artikel i tidskrift (Refereegranskat)
  • 4.
    Almqvist, Bjarne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Koyi, Hemin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Bulk strain in orogenic wedges based on insights from magnetic fabrics in sandbox models2018Ingår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 46, nr 6, s. 483-486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anisotropy of magnetic susceptibility (AMS) analysis is used as a petrofabric indicator for a set of four identical-setup sandbox models that were shortened by different amounts and simulate contraction in a fold-and-thrust belt. During model shortening, a progressive reorientation of the initial magnetic fabric occurs due to horizontal compaction of the sand layers. At the early stages of shortening, magnetic lineation (k(1) axis) rotates parallel to the model backstop with subhorizontal orientation, whereas the minimum susceptibility (k(3) axis) is subvertical, which indicates a partial tectonic overprint of the initial fabric. With further shortening, the k(3) axis rotates to subhorizontal orientation, parallel to shortening direction, marking the development of a dominant tectonic magnetic fabric. A near-linear transition in magnetic fabric is observed from the initial bedding to tectonic fabric in all four models, which reflects a progressive transition in deformation from foreland toward hinterland. Model results confirm a long-held hypothesis where the AMS pattern and degree of anisotropy have been suggested to reflect the amount of layer-parallel shortening, based on field observations in many mountain belts. Results furthermore indicate that grain rotation may play a significant role in low-grade compressive tectonic regimes. The combination of analogue models with AMS enables the possibility to predict magnetic fabrics in different tectonic settings and to develop quantitative links between AMS and strain.

  • 5.
    Almqvist, Bjarne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Misra, Santanu
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Mainprice, David
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Ultrasonic velocity drops and anisotropy reduction in mica-schist analogues due to melting with implications for seismic imaging of continental crust2015Ingår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 425, s. 24-33Artikel i tidskrift (Refereegranskat)
  • 6.
    Andersson, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Almqvist, Bjarne S. G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Malehmir, Alireza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Snowball, Ian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling.
    Kubler, Lutz
    Geol Survey Sweden, Uppsala, Sweden..
    Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 27635Artikel i tidskrift (Refereegranskat)
    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.

  • 7.
    Andersson, Stefan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Helsinki, Dept Geosci & Geog, FI-00014 Helsinki, Finland.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, Uppsala, Sweden.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Metamorphism and deformation of a Palaeoproterozoic polymetallic sulphide-oxide mineralisation: Hornkullen, Bergslagen, Sweden2016Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, nr 3, s. 410-423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Hornkullen mineralisation is situated in the westernmost part of the Bergslagen ore province, south-central Sweden. Here, polymetallic sulphides and oxides are hosted by an inlier of Svecofennian, c. 1.9Ga skarn-bearing metavolcanic units, enclosed in the c. 1.8Ga Filipstad granite belonging to the Transscandinavian Igneous Belt. The Ag- and Au-bearing mineralisation is dominated by veins and impregnations of magnetite, pyrrhotite, galena, chalcopyrite and arsenopyrite with subordinate pyrite, sphalerite, ilmenite, lollingite, Pb-Fe-Ag-Cu-Sb sulphosalts and rare gudmundite, pentlandite and molybdenite. Overall, a detailed textural and mineralogical study of the ore assemblages suggests significant deformation and remobilisation at high temperature, which is corroborated by sulphide geothermobarometry. The arsenopyrite geothermometer yields an average temperature of c. 525 degrees C, which is likely to be the result of metamorphic re-equilibration. Sphalerite geobarometry gives peak pressures of c. 300-400MPa, albeit with caveats. The combined observations suggest that the present mineralogical and textural nature of the ore assemblages at Hornkullen is primarily related to remobilisation during Svecokarelian regional metamorphism of a pre-existing, most likely syn-volcanic mineralisation. This scenario is likely to be applicable to many other Svecofennian metasupracrustal-hosted deposits in the Bergslagen ore province.

  • 8.
    Andersson, Stefan S.
    et al.
    Univ Helsinki, Dept Geosci & Geog, POB 64,Gustaf Hallstromin Katu 2a, FI-00014 Helsinki, Finland..
    Wagner, Thomas
    Rhein Westfal TH Aachen, Inst Appl Mineral & Econ Geol, Wullnerstr 2, D-52062 Aachen, Germany..
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, Uppsala, Sweden.;Uppsala Univ, Dept Earth Sci, Villavagen 16, SE-75266 Uppsala, Sweden..
    Michallik, Radoslaw M.
    Univ Helsinki, Dept Geosci & Geog,Gustaf Hallstromin Katu 2a, FI-00014 Helsinki, Finland..
    Mineralogy, paragenesis, and mineral chemistry of REEs in the Olserum-Djupedal REE-phosphate mineralization, SE Sweden2018Ingår i: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 103, nr 1, s. 125-142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rapidly growing use of rare earth elements and yttrium (REE) in modern-day technologies, not least within the fields of green and carbon-free energy applications, requires exploitation of new REE deposits and deposit types. In this perspective, it is vital to develop a fundamental understanding of the behavior of REE in natural hydrothermal systems and the formation of hydrothermal REE deposits. In this study, we establish a mineralogical, textural, and mineral-chemical framework for a new type of deposit, the hydrothermal Olserum-Djupedal REE-phosphate mineralization in SE Sweden. An early, high-temperature REE stage is characterized by abundant monazite-(Ce) and xenotime-(Y) coexisting with fluorapatite and subordinate amounts of (Y,REE,U,Fe)-(Nb,Ta) oxides. During a subsequent stage, allanite-(Ce) and ferriallanite-(Ce) formed locally, partly resulting from the breakdown of primary monazite-(Ce). Alteration of allanite-(Ce) or ferriallanite-(Ce) to bastnasite-(Ce) and minor synchysite-(Ce) at lower temperatures represents the latest stage of REE mineral formation. The paragenetic sequence and mineral chemistry of the allanites record an increase in Ca content in the fluid. We suggest that this local increase in Ca, in conjunction with changes in oxidation state, were the key factors controlling the stability of monazite-(Ce) in the assemblages of the Olserum-Djupedal deposit. We interpret the alteration and replacement of primary monazite-(Ce), xenotime-(Y), fluorapatite, and minor (Y,REE,U,Fe)-(Nb, Ta) oxide phase(s), to be the consequence of coupled dissolution-reprecipitation processes. These processes mobilized REE,Th,U, and Nb-Ta, which caused the formation of secondary monazite-(Ce), xenotime-(Y), fluorapatite, and minor amounts of allanite-(Ce) and ferriallanite-(Ce). In addition, these alteration processes produced uraninite, thorite, columbite-(Fe), and uncharacterized (Th,U,Y,Ca)-silicates. Textural relations show that the dissolution-reprecipitation processes affecting fluorapatite preceded those affecting monazite-(Ce), xenotime-(Y), and the (Y, REE, U, Fe)-(Nb, Ta) oxide phase(s). The mineralogy of the primary ore mineralization and the subsequently formed alteration assemblages demonstrate the combined mobility of REE and HFSE in a natural F-bearing high-temperature hydrothermal system. The observed coprecipitation of monazite-(Ce), xenotime-(Y), and fluorapatite during the primary REE mineralization stage highlights the need for further research on the potentially important role of the phosphate ligand in hydrothermal REE transporting systems.

  • 9.
    Andrén, Margareta
    et al.
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Stockmann, Gabrielle
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Skelton, Alasdair
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Sturkell, Erik
    Univ Gothenburg, Dept Earth Sci, Gothenburg, Sweden.
    Mörth, Carl-Magnus
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Guðrúnardóttir, Helga Rakel
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Keller, Nicole Simone
    Univ Iceland, Inst Earth Sci, Reykjavik, Iceland.
    Odling, Nic
    Univ Edinburgh, Sch Geosci, Edinburgh, Midlothian, Scotland.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Broman, Curt
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Balic-Zunic, Tonci
    Univ Copenhagen, Nat Hist Museum, Copenhagen, Denmark.
    Hjartarsson, Hreinn
    Landsvirkjun, Reykjavik, Iceland.
    Siegmund, Heike
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden.
    Freund, Friedemann
    NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA.
    Kockum, Ingrid
    NASA, Ames Res Ctr, Div Earth Sci, Moffett Field, CA 94035 USA.
    Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland2016Ingår i: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 121, nr 4, s. 2315-2337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 10.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. 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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    The magma plumbing system for the 1971 Teneguía eruption on La Palma, Canary Islands2015Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 170, nr 5-6, artikel-id 54Artikel i tidskrift (Refereegranskat)
    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. 

  • 11.
    Berg, Sylvia E.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Las Palmas Gran Canaria, GEOVOL, Las Palmas Gran Canaria, Spain.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Krumbholz, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. 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 microtomography2016Ingår i: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 78, nr 12, artikel-id 85Artikel i tidskrift (Refereegranskat)
    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.

  • 12.
    Berg, Sylvia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Gústafsson, Ludvik E.
    Samband Islenskra Sveitarfélag, Borgartúni 30, pósthólf 8100, 128 Reykjavik, Iceland.
    Rapid high-silica magma generation in basalt-dominated rift settings2015Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Blythe, Lara
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi. School of Physical and Geographical Science, Keele University, Keele, UK.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Freda, C
    Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
    CO2 bubble generation and migration during magma–carbonate interaction2015Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 169, nr 4, artikel-id 42Artikel i tidskrift (Refereegranskat)
    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.

  • 14. Bosi, Ferdinando
    et al.
    Skogby, Henrik
    Lazor, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Reznitskii, Leonid
    Atomic arrangements around the O3 site in Al- and Cr-rich oxytourmalines: a combined EMP, SREF, FTIR and Raman study2015Ingår i: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, nr 6, s. 441-453Artikel i tidskrift (Refereegranskat)
  • 15.
    Boskabadi, Arman
    et al.
    Univ Texas Dallas, Dept Geosci, ROC 21,800 West Campbell Rd, Richardson, TX 75080 USA.;Stockholm Univ, Dept Geol Sci, Stockholm, Sweden..
    Pitcairn, Iain K.
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden..
    Broman, Curt
    Stockholm Univ, Dept Geol Sci, Stockholm, Sweden..
    Boyce, Adrian
    Scottish Univ Environm Res Ctr, E Kilbride, Lanark, Scotland..
    Teagle, Damon A. H.
    Univ Southampton, Natl Oceanog Ctr Southampton, Southampton, Hants, England..
    Cooper, Matthew J.
    Univ Southampton, Natl Oceanog Ctr Southampton, Southampton, Hants, England..
    Azer, Mokhles K.
    Natl Res Ctr, Dept Geol, Cairo, Egypt..
    Stern, Robert J.
    Univ Texas Dallas, Dept Geosci, ROC 21,800 West Campbell Rd, Richardson, TX 75080 USA..
    Mohamed, Fathy H.
    Univ Alexandria, Dept Geol, Fac Sci, Alexandria, Egypt..
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Krakow, Poland..
    Carbonate alteration of ophiolitic rocks in the Arabian-Nubian Shield of Egypt: sources and compositions of the carbonating fluid and implications for the formation of Au deposits2017Ingår i: International Geology Review, ISSN 0020-6814, E-ISSN 1938-2839, Vol. 59, nr 4, s. 391-419Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Ultramafic portions of ophiolitic fragments in the Arabian-Nubian Shield (ANS) show pervasive carbonate alteration forming various degrees of carbonated serpentinites and listvenitic rocks. Notwithstanding the extent of the alteration, little is known about the processes that caused it, the source of the CO2 or the conditions of alteration. This study investigates the mineralogy, stable (O, C) and radiogenic (Sr) isotope composition, and geochemistry of suites of variably carbonate altered ultramafics from the Meatiq area of the Central Eastern Desert (CED) of Egypt. The samples investigated include least-altered lizardite (Lz) serpentinites, antigorite (Atg) serpentinites and listvenitic rocks with associated carbonate and quartz veins. The C, O and Sr isotopes of the vein samples cluster between -8.1 parts per thousand and -6.8 parts per thousand for delta C-13, +6.4 parts per thousand and +10.5 parts per thousand for delta O-18, and Sr-87/Sr-86 of 0.7028-0.70344, and plot within the depleted mantle compositional field. The serpentinites isotopic compositions plot on a mixing trend between the depleted-mantle and sedimentary carbonate fields. The carbonate veins contain abundant carbonic (CO2 +/- CH4 +/- N-2) and aqueous-carbonic (H2O-NaCl-CO2 +/- CH4 +/- N-2) low salinity fluid, with trapping conditions of 270-300 degrees C and 0.7-1.1kbar. The serpentinites are enriched in Au, As, S and other fluid-mobile elements relative to primitive and depleted mantle. The extensively carbonated Atg-serpentinites contain significantly lower concentrations of these elements than the Lz-serpentinites suggesting that they were depleted during carbonate alteration. Fluid inclusion and stable isotope compositions of Au deposits in the CED are similar to those from the carbonate veins investigated in the study and we suggest that carbonation of ANS ophiolitic rocks due to influx of mantle-derived CO2-bearing fluids caused break down of Au-bearing minerals such as pentlandite, releasing Au and S to the hydrothermal fluids that later formed the Au-deposits. This is the first time that gold has been observed to be remobilized from rocks during the lizardite-antigorite transition.

  • 16.
    Budd, David A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Characterising volcanic magma plumbing systems: A tool to improve eruption forecasting at hazardous volcanoes2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis attempts to develop our understanding of volcanic magma plumbing systems and the magmatic processes that operate within them, such as fractional crystallisation, crustal partial melting, assimilation, and magma mixing. I utilise petrology, rock and mineral geochemistry, and isotope systematics to seek to improve our ability to forecast the eruptive frequency and style of active volcanoes, an aspect often lacking in current volcano monitoring efforts. In particular, magma reservoir dynamics are investigated from a mineral scale at Katla volcano in Iceland, to a sub-mineral scale at Merapi, Kelud, and Toba volcanoes in Indonesia.

    The magma plumbing architecture of Katla volcano on Iceland is explored in the first part of this thesis. Crystalline components within tephra and volcanic rock preserve a record of the physical and chemical evolution of a magma, and are analysed through oxygen isotopic and thermobarometric techniques to temporally constrain changes in reservoir depth and decode the petrogenesis of the lavas. We find both prolonged upper crustal magma storage and shallow level assimilation to be occurring at Katla. The results generated from combining these analytical strands reveal the potential for unpredictable explosive volcanism at this lively Icelandic volcano.

    The second part of this thesis examines the magma plumbing systems of Merapi, Kelud and Toba volcanoes of the Sunda arc in Indonesia at higher temporal and petrological resolution than possible for Katla (e.g., due to the crystal poor character of the rocks). For this part of the thesis, minerals were analysed in-situ to take advantage of sub-crystal scale isotopic variations in order to investigate processes of shallow-level assimilation in the build-up to particular eruptions. We find that intra-crystal analyses reveal an otherwise hidden differentiation history at these volcanoes, and establish a better understanding as to how they may have rapidly achieved a critical explosive state.

    The outcomes of this thesis therefore deepen our knowledge of evolutionary trends in magma plumbing system dynamics, and highlight the importance of understanding the geochemical processes that can prime a volcano for eruption. Lastly, I emphasise the vital contribution petrology can make in current volcano monitoring efforts. 

    Delarbeten
    1. Persistent two-tiered magma plumbing beneath Katla volcano, Iceland
    Öppna denna publikation i ny flik eller fönster >>Persistent two-tiered magma plumbing beneath Katla volcano, Iceland
    (Engelska)Ingår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027Artikel i tidskrift (Refereegranskat) Submitted
    Nationell ämneskategori
    Geologi
    Forskningsämne
    Geovetenskap med inriktning mot mineralogi, petrologi och tektonik
    Identifikatorer
    urn:nbn:se:uu:diva-267448 (URN)
    Tillgänglig från: 2015-11-23 Skapad: 2015-11-23 Senast uppdaterad: 2017-12-01
    2. Petrogenetic constraints on the Katla rhyolites, South Iceland
    Öppna denna publikation i ny flik eller fönster >>Petrogenetic constraints on the Katla rhyolites, South Iceland
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geologi
    Identifikatorer
    urn:nbn:se:uu:diva-267451 (URN)
    Tillgänglig från: 2015-11-23 Skapad: 2015-11-23 Senast uppdaterad: 2016-01-13
    3. New augite and enstatite pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia
    Öppna denna publikation i ny flik eller fönster >>New augite and enstatite pyroxene standards for SIMS oxygen isotope analysis and their application to Merapi volcano, Sunda arc, Indonesia
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Multidisciplinär geovetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-267452 (URN)
    Tillgänglig från: 2015-11-23 Skapad: 2015-11-23 Senast uppdaterad: 2016-04-27
    4. Sudden Plinian eruption of remnant magmas at Kelud volcano, Java, Indonesia
    Öppna denna publikation i ny flik eller fönster >>Sudden Plinian eruption of remnant magmas at Kelud volcano, Java, Indonesia
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geologi
    Identifikatorer
    urn:nbn:se:uu:diva-267472 (URN)
    Tillgänglig från: 2015-11-23 Skapad: 2015-11-23 Senast uppdaterad: 2016-01-13
    5. Magma reservoir dynamics recorded by oxygen isotope zoning in quartz
    Öppna denna publikation i ny flik eller fönster >>Magma reservoir dynamics recorded by oxygen isotope zoning in quartz
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Geologi
    Identifikatorer
    urn:nbn:se:uu:diva-267454 (URN)
    Tillgänglig från: 2015-11-23 Skapad: 2015-11-23 Senast uppdaterad: 2016-01-13
    6. Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.
    Öppna denna publikation i ny flik eller fönster >>Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.
    Visa övriga...
    2015 (Engelska)Ingår i: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, nr 1, s. 137-166Artikel i tidskrift (Refereegranskat) Published
    Nationell ämneskategori
    Multidisciplinär geovetenskap
    Forskningsämne
    Geovetenskap med inriktning mot mineralogi, petrologi och tektonik
    Identifikatorer
    urn:nbn:se:uu:diva-240752 (URN)10.1111/geoa.12099 (DOI)000350500400010 ()
    Tillgänglig från: 2015-01-08 Skapad: 2015-01-08 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
    7. Traversing nature's danger zone: getting up close with Sumatra's volcanoes
    Öppna denna publikation i ny flik eller fönster >>Traversing nature's danger zone: getting up close with Sumatra's volcanoes
    Visa övriga...
    2012 (Engelska)Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 28, nr 2, s. 64-70Artikel i tidskrift (Refereegranskat) Published
    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.

    Nationell ämneskategori
    Geovetenskap och miljövetenskap
    Forskningsämne
    Geovetenskap med inriktning mot mineralogi, petrologi och tektonik
    Identifikatorer
    urn:nbn:se:uu:diva-188509 (URN)10.1111/j.1365-2451.2012.00828.x (DOI)
    Tillgänglig från: 2012-12-17 Skapad: 2012-12-17 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
  • 17.
    Budd, David A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Dahren, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Persistent multitiered magma plumbing beneath Katla volcano, Iceland2016Ingår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 17, nr 3, s. 966-980Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Budd, David A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Ist Nazl Geofis & Vulcanol, Rome, Italy.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden.
    Jolis, Ester
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    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 quartz2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 40624Artikel i tidskrift (Refereegranskat)
    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.

  • 19.
    Budd, David
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Persistent two-tiered magma plumbing beneath Katla volcano, IcelandIngår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027Artikel i tidskrift (Refereegranskat)
  • 20.
    Budd, David
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jolis, Ester
    Smith, Victoria
    Whitehouse, Martin
    Harris, Chris
    Freda, Carmela
    Hilton, David
    Halldórsson, Sæmundur
    Bindeman, Ilya
    Magma reservoir dynamics recorded by oxygen isotope zoning in quartzManuskript (preprint) (Övrigt vetenskapligt)
  • 21.
    Budd, David
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Harris, Chris
    Meyer, Romain
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Petrogenetic constraints on the Katla rhyolites, South IcelandManuskript (preprint) (Övrigt vetenskapligt)
  • 22.
    Budzyn, Bartosz
    et al.
    Polish Acad Sci, Res Ctr Krakow ING PAN, Inst Geol Sci, Senacka 1, PL-31002 Krakow, Poland..
    Harlov, Daniel E.
    Geoforschungszentrum Potsdam, D-14473 Potsdam, Germany.;Univ Johannesburg, Dept Geol, POB 524, ZA-2006 Auckland Pk, South Africa..
    Kozub-Budzyn, Gabriela A.
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al A Mickiewicza 30, PL-30059 Krakow, Poland..
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al A Mickiewicza 30, PL-30059 Krakow, Poland..
    Experimental constraints on the relative stabilities of the two systems monazite-(Ce) - allanite-(Ce) - fluorapatite and xenotime-(Y) - (Y,HREE)-rich epidote - (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200-1000 MPa and 450-750 A degrees C2017Ingår i: Mineralogy and Petrology, ISSN 0930-0708, E-ISSN 1438-1168, Vol. 111, nr 2, s. 183-217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The relative stabilities of phases within the two systems monazite-(Ce) - fluorapatite - allanite-(Ce) and xenotime-(Y) - (Y,HREE)-rich fluorapatite - (Y,HREE)-rich epidote have been tested experimentally as a function of pressure and temperature in systems roughly replicating granitic to pelitic composition with high and moderate bulk CaO/Na2O ratios over a wide range of P-T conditions from 200 to 1000 MPa and 450 to 750 A degrees C via four sets of experiments. These included (1) monazite-(Ce), labradorite, sanidine, biotite, muscovite, SiO2, CaF2, and 2 M Ca(OH)(2); (2) monazite-(Ce), albite, sanidine, biotite, muscovite, SiO2, CaF2, Na2Si2O5, and H2O; (3) xenotime-(Y), labradorite, sanidine, biotite, muscovite, garnet, SiO2, CaF2, and 2 M Ca(OH)(2); and (4) xenotime-(Y), albite, sanidine, biotite, muscovite, garnet, SiO2, CaF2, Na2Si2O5, and H2O. Monazite-(Ce) breakdown was documented in experimental sets (1) and (2). In experimental set (1), the Ca high activity (estimated bulk CaO/Na2O ratio of 13.3) promoted the formation of REE-rich epidote, allanite-(Ce), REE-rich fluorapatite, and fluorcalciobritholite at the expense of monazite-(Ce). In contrast, a bulk CaO/Na2O ratio of similar to 1.0 in runs in set (2) prevented the formation of REE-rich epidote and allanite-(Ce). The reacted monazite-(Ce) was partially replaced by REE-rich fluorapatite-fluorcalciobritholite in all runs, REE-rich steacyite in experiments at 450 A degrees C, 200-1000 MPa, and 550 A degrees C, 200-600 MPa, and minor cheralite in runs at 650-750 A degrees C, 200-1000 MPa. The experimental results support previous natural observations and thermodynamic modeling of phase equilibria, which demonstrate that an increased CaO bulk content expands the stability field of allanite-(Ce) relative to monazite-(Ce) at higher temperatures indicating that the relative stabilities of monazite-(Ce) and allanite-(Ce) depend on the bulk CaO/Na2O ratio. The experiments also provide new insights into the re-equilibration of monazite-(Ce) via fluid-aided coupled dissolution-reprecipitation, which affects the Th-U-Pb system in runs at 450 A degrees C, 200-1000 MPa, and 550 A degrees C, 200-600 MPa. A lack of compositional alteration in the Th, U, and Pb in monazite-(Ce) at 550 A degrees C, 800-1000 MPa, and in experiments at 650-750 A degrees C, 200-1000 MPa indicates the limited influence of fluid-mediated alteration on volume diffusion under high P-T conditions. Experimental sets (3) and (4) resulted in xenotime-(Y) breakdown and partial replacement by (Y,REE)-rich fluorapatite to Y-rich fluorcalciobritholite. Additionally, (Y,HREE)-rich epidote formed at the expense of xenotime-(Y) in three runs with 2 M Ca(OH)(2) fluid, at 550 A degrees C, 800 MPa; 650 A degrees C, 800 MPa; and 650 A degrees C, 1000 MPa similar to the experiments involving monazite-(Ce). These results confirm that replacement of xenotime-(Y) by (Y,HREE)-rich epidote is induced by a high Ca bulk content with a high CaO/Na2O ratio. These experiments demonstrate also that the relative stabilities of xenotime-(Y) and (Y,HREE)-rich epidote are strongly controlled by pressure.

  • 23.
    Buntin, Sebastian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Malehmir, Alireza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Malinowski, Michal
    Polish Academy of Sciences.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Juhlin, Christopher
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Thybo, Hans
    University of Copenhagen, Denmark.
    Buske, Stefan
    TUBAF, Germany.
    Seismic reprocessing of the BABEL lines for improved interpretation of the whole crust – preliminary results2016Ingår i: Lithosphere 2016: Ninth Symposium On Structure, Composition And Evolution Of The Lithosphere In Fennoscandia / [ed] Ilmo Kukkonen, Suvi Heinonen, Kati Oinonen, Katriina Arhe, Olav Eklund, Fredrik Karell, Elena Kozlovskaya, Arto Luttinen, Raimo Lahtinen, Juha Lunkka, Vesa Nykänen, Markku Poutanen , Eija Tanskanen and Timo Tiira, Helsinki, Finland: University of Helsinki, Institute of Seismology , 2016, s. 9-12Konferensbidrag (Refereegranskat)
    Abstract [en]

    This ongoing study focuses on the reprocessing of the historical BABEL (Baltic and Bothnian Echoes from the Lithosphere, 1989) seismic lines in the Bay of Bothnia in preparation for the acquisition of a 400 km long onshore reflection and refraction profile in central part of Sweden. The main aim of the project is to increase the understanding of the tectonic evolution of the mineral-rich Bergslagen region both offshore and onshore. The seismic data have been recovered and currently being reprocessed using up-to-date processing methods and preliminary results show promising outcome from this work.

  • 24.
    Burchardt, Steffi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Koyi, Hemin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Schmeling, Harro
    Fuchs, Lukas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Sinking of anhydrite blocks within a Newtonian salt diapir: modelling the influence of block aspect ratio and salt stratification2012Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 188, nr 3, s. 763-778Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    2-D Finite Differences models are used to analyse the strain produced by gravity-driven sinking of dense rectangular inclusions through homogeneous and vertically stratified Newtonian salt. We systematically modelled the descent of dense blocks of different sizes and initial orientations (aspect ratios) representing the Main Anhydrite fragments documented within, for example, the Gorleben salt diapir. Model results demonstrate that size of the blocks is a governing parameter which dictates the amount of strain produced within the block and in the surrounding host salt. Initial block orientation (aspect ratio), on the other hand, causes fundamental differences in block deformation, while the resulting structures produced in the salt are principally the same in all models with homogeneous salt, covering shear zones and folding of passive markers. In models with vertically stratified salt with different viscosities, block descent takes place along complex paths. This results from greater strain accommodation by the salt formation with the lowest viscosity and an asymmetrical distribution of initial vertical shear stresses around the block. Consequently, in these models, block strain is lower compared with the models with homogeneous salt (for the same viscosity as the high-viscosity salt), and sinking is accompanied by block rotation. The latter causes diapir-scale disturbance of the pre-sinking salt stratigraphy and complex sinking paths of the blocks. In particular, vertically oriented blocks sink into high-viscosity salt and drag with them some low-viscosity salt, while horizontal blocks sink in the low-viscosity salt. The resultant sinking velocities vary strongly depending on the sinking path of the block. Based on model results and observed structural configuration within the Gorleben salt diapir, we conclude that the internal complexity of a salt diapir governs its post-ascent deformation. Salt structure and its interaction with dense blocks should hence be considered in the assessment of the long-term stability of storage sites for hazardous waste.

  • 25.
    Burchardt, Steffi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Schmeling, Harro
    Goethe Univ Frankfurt, Fac Earth Sci, Altenhoferallee 1, D-60438 Frankfurt, Germany..
    Koyi, Hemin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Blythe, Lara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Erupted frothy xenoliths may explain lack of country-rock fragments in plutons2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 34566Artikel i tidskrift (Refereegranskat)
    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.

  • 26. Busby, CJ
    et al.
    Tamura, Y
    Blum, P
    Guerin, G
    Andrews, GDM
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Berger, Julien LR
    Bongiolo, EM
    Bordiga, Manuela
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    DeBari, SM
    Gill, JB
    Hamelin, C
    Jia, Jihui
    John, EH
    Jonas, Ann-Sophie
    Jutzeler, Martin
    Kars, Myriam AC
    Kita, Zachary A
    Konrad, Kevin
    Mahony, Susan H
    Martini, Michelangelo
    Miyazaki, Takashi
    Musgrave, Robert J
    Nascimento, Debara B
    Nichols, Alexander R L
    Ribeiro, Julia M
    Sato, Tomoki
    Schindlbeck, Julie C
    Schmitt, Axel K
    Straub, Susanne M
    Mleneck-Vautravers, Maryline J
    Yang, Alexandra Yang
    The missing half of the subduction factory: shipboard results from the Izu rear arc, IODP expedition 3502017Ingår i: International Geology Review, ISSN 0020-6814, E-ISSN 1938-2839, Vol. 59, nr 13, s. 1677-1708Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although severalsites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand theevolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporalrecord (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chainsup to ~100-km long roughly perpendicular to the arc front. Dredge samples from these aregeochemically distinct from arc front rocks, and drilling was undertaken to understand this arcasymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-kmwest of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery.We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected(~60%), and the remaining fraction of the section is much finer-grained than predicted from itsposition within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size(clasts <3 cm). Volcanic blocks (>6.4 cm) are only sparsely scattered through the lowermost 25% ofthe section, and only one igneous unit was encountered, a rhyolite peperite intrusion at~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagneticdatum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zirconconcordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed tothe fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcani-clastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arcasymmetry is not recorded in rocks older than ~13 Ma.

  • 27. Byrne, P.
    et al.
    Holohan, E
    Kervyn, M
    van Wyk de Vries, B.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Analogue modelling of volcano flank terrace formation on Mars2015Ingår i: Volcanism and Tectonism Across the Inner Solar System / [ed] Platz, T., Massironi M., Byrne P.K. and Hisinger H., Geological Society of London, 2015Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 28.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Wiesmaier, Sebastian
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    The 2011 submarine volcanic eruption in El Hierro (Canary Islands)2012Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 28, nr 2, s. 53-58Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    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.

  • 29.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, ValentinUppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Teide Volcano: Geology and Eruptions of a Highly Differentiated Oceanic Stratovolcano2013Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
    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.

  • 30.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    The Geology of the Canary Islands2016Bok (Övrigt vetenskapligt)
  • 31. Carracedo, Juan Carlos
    et al.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Zaczek, Kirsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Rodriguez-Gonzales, Alejandro
    Soler, Vincente
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    The 2011-2012 submarine eruption off El Hierro, Canary Islands: New lessons in oceanic island growth and volcanic crisis management2015Ingår i: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 150, s. 168-200Artikel i tidskrift (Refereegranskat)
    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.

  • 32.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Volcanic and structural evolution of Pico do Fogo, Cape Verde2015Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, nr 4, s. 146-152Artikel i tidskrift (Refereegranskat)
    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.

  • 33.
    Carrillo, Emilio
    et al.
    Univ Barcelona, Dept Geoquim Petr & Prospeccio Geol, C Marti & Franques S-N, E-08028 Barcelona, Spain.;Yachay Tech Univ, Sch Geol Sci & Engn, Hacienda San Jose S-N, San Miguel De Urcuqui, Ecuador..
    Koyi, Hemin A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Nilforoushan, Faramarz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.;Lantmateriet, Gavle, Sweden..
    Structural significance of an evaporite formation with lateral stratigraphic heterogeneities (Southeastern Pyrenean Basin, NE Spain)2017Ingår i: Marine and Petroleum Geology, ISSN 0264-8172, E-ISSN 1873-4073, Vol. 86, s. 1310-1326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We run a series of analogue models to study the effect of stratigraphic heterogeneities of an evaporite formation on thin-skinned deformation of the Southeastern Pyrenean Basin (SPB; NE Spain). This basin is characterized by the existence of evaporites, deposited during the Early-Middle Eocene with lateral variations in thickness and lithological composition. These evaporites are distributed in three lithostratigraphic units, known as Serrat Evaporites, Vallfogona and Beuda Gypsum formations and acted as decollement levels, during compressional deformation in the Lutetian. In addition to analogue modeling, we have used field data, detailed geological mapping and key cross-sections supported by seismic and well data to build a new structural interpretation for the SPB. In this interpretation, it is recognized that the basal and upper parts of the Serrat Evaporites acted as the main decollement levels of the so-called Cadi thrust sheet and Serrat unit. A balanced restoration of the basin indicates that thrust faults nucleated at the stratigraphic transition of the Serrat Evaporites (zone with lateral variations of thickness and lithological composition), characterized by a wedge of anhydrite and shale. The analogue models were setup based on information extracted from cross-sections, built in two sectors with different lithology and stratigraphy of the evaporites, and the restored section of the SPB. In these models, deformation preferentially concentrated in areas where thickness change, defined by wedges of the ductile materials, was inbuilt. Based on the structural interpretation and model results, a kinematic evolution of the SPB is proposed. The kinematic model is characterized by the generation of out-of-sequence structures developed due to lateral stratigraphic variations of the Serrat Evaporites. The present work shows a good example of the role of stratigraphic heterogeneities of an evaporite formation which acts as decollement level on structural deformation in a fold-thrust belt. The results of this work have implications for hydrocarbon exploration and are relevant for studying structural geometry and mechanics in shortened evaporite basins. (C) 2017 Elsevier Ltd. All rights reserved.

  • 34.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Muir, Duncan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    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 explosivity2016Ingår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 44, nr 12, s. 1027-1030Artikel i tidskrift (Refereegranskat)
    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.

  • 35.
    Chew, David M.
    et al.