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  • 101.
    Longpré, Marc-Antoine
    et al.
    Department of Geology, Trinity College Dublin, Dublin, Ireland.
    Troll, Valentin
    Hansteen, Thor H.
    IFM-GEOMAR, Wischhofstrasse 1-3, D-24148 Kiel, Germany.
    Upper mantle magma storage and transport under a Canarian shield-volcano, Teno, Tenerife (Spain)2008Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, artikel-id B08203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use clinopyroxene-liquid thermobarometry, aided by petrography and mineral major element chemistry, to reconstruct the magma plumbing system of the late Miocene, largely mafic Teno shield-volcano on the island of Tenerife. Outer rims of clinopyroxene and olivine phenocrysts show patterns best explained by decompression-induced crystallization upon rapid ascent of magmas from depth. The last equilibrium crystallization of clinopyroxene occurred in the uppermost mantle, from ∼20 to 45 km depth. We propose that flexural stresses or, alternatively, thermomechanical contrasts create a magma trap that largely confines magma storage to an interval roughly coinciding with the Moho at ∼15 km and the base of the long-term elastic lithosphere at ∼40 km below sea level. Evidence for shallow magma storage is restricted to the occurrence of a thick vitric tuff of trachytic composition emplaced before the Teno shield-volcano suffered large-scale flank collapses. The scenario developed in this study may help shed light on some unresolved issues of magma supply to intraplate oceanic volcanoes characterized by relatively low magma fluxes, such as those of the Canary, Madeira and Cape Verde archipelagoes, as well as Hawaiian volcanoes in their postshield stage. The data presented also support the importance of progressive magmatic underplating in the Canary Islands.

  • 102. Longpré, Marc-Antoine
    et al.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Walter, Thomas R.
    Hansteen, Thor H.
    Volcanic and geochemical evolution of the Teno massif, Tenerife, Canary Islands: Some repercussions of giant landslides on ocean island magmatism2009Ingår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 10, nr 12, s. 31-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Large-scale, catastrophic mass wasting is a major process contributing to the dismantling of oceanic intraplate volcanoes. Recent studies, however, have highlighted a possible feedback relationship between flank collapse, or incipient instability, and subsequent episodes of structural rearrangement and/or renewed volcano growth. The Teno massif, located in northwestern Tenerife (Canary Islands), is a deeply eroded Miocene shield volcano that was built in four major eruptive phases punctuated by two lateral collapses, each removing >20–25 km3 of the volcano's north flank. In this paper, we use detailed field observations and petrological and geochemical data to evaluate possible links between large-scale landslides and subsequent volcanism/magmatism during Teno's evolution. Inspection of key stratigraphic sequences reveals that steep angular unconformities, relics of paleolandslide scars, are marked by polymict breccias. Near their base, these deposits typically include abundant juvenile pyroclastic material, otherwise scarce in the region. While some of Teno's most evolved, low-density magmas were produced just before flank collapses, early postlandslide lava sequences are characterized by anomalously high proportions of dense ankaramite flows, extremely rich in clinopyroxene and olivine crystals. A detailed sampling profile shows transitions from low-Mg # lavas relatively rich in SiO2 to lavas with low silica content and comparatively high Mg # after both landslides. Long-term variations in Zr/Nb, normative nepheline, and La/Lu are coupled but do not show a systematic correlation with stratigraphic boundaries. We propose that whereas loading of the growing precollapse volcano promoted magma stagnation and differentiation, the successive giant landslides modified the shallow volcano-tectonic stress field at Teno, resulting in widespread pyroclastic eruptions and shallow magma reservoir drainage. This rapid unloading of several tens of km3 of near-surface rocks appears to have upset magma differentiation processes, while facilitating the remobilization and tapping of denser ankaramite magmas that were stored in the uppermost mantle. Degrees of mantle melting coincidently reached a maximum in the short time interval between the two landslides and declined shortly after, probably reflecting intrinsic plume processes rather than a collapse-induced influence on mantle melting. Our study of Teno volcano bears implications for other oceanic volcanoes where short-term compositional variations may also directly relate to major flank collapse events.

  • 103.
    Majka, Jaroslaw
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harlov, D.
    Nilsson, K.P.
    Textural relations and mineral chemistry of REE in the Grängesberg apatite-iron oxide deposit, Sweden: the role of fluids2013Ingår i: Mineral deposit research for a high-tech world, s. 1728-1731Artikel i tidskrift (Refereegranskat)
  • 104. Manconi, Andrea
    et al.
    Longpré, Marc-Antoine
    Walter, Thomas R.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Hansteen, Thor H.
    The effects of flank collapses on volcano plumbing systems2009Ingår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 37, nr 12, s. 1099-1102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growth of large volcanoes is commonly interrupted by episodes of flank collapse that may be accompanied by catastrophic debris avalanches, explosive eruptions, and tsunamis. El Hierro, the youngest island of the Canary Archipelago, has been repeatedly affected by such mass-wasting events in the last 1 Ma. Our field observations and petrological data suggest that the largest and most recent of these flank collapses—the El Golfo landslide—likely influenced the magma plumbing system of the island, leading to the eruption of higher proportions of denser and less evolved magmas. The results of our numerical simulations indicate that the El Golfo landslide generated pressure changes exceeding 1 MPa down to upper-mantle depths, with local amplification in the surroundings and within the modeled magma plumbing system. Stress perturbations of that order might drastically alter feeding system processes, such as degassing, transport, differentiation, and mixing of magma batches.

  • 105. Masotta, Matteo
    et al.
    Freda, Carmela
    Paul, Tracy A.
    Moore, Gordon M.
    Gaeta, Mario
    Scarlato, Piergiorgio
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Low pressure experiments in piston cylinder apparatus: Calibration of newly designed 25 mm furnace assemblies to P=150 MPa2012Ingår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 312, s. 74-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present new pressure calibration experiments demonstrating that the piston cylinder apparatus is suitable for experiments at pressure as low as 150 MPa. Two newly designed 25 mm furnace assembly have been developed and calibrated using two different calibration methods: the NaCl melting curve and the solubility of H2O in albitic and rhyolitic melts. The NaCl calibration experiments performed in the pressure range 150-500 MPa yield the pressure correction that has to be applied to the nominal pressure in order to have the equivalent (real) pressure on the sample. This correction varies as a function of the experimental pressure as follows: P-correction(MPa) = -0.115xP(nominal)(MPa) + 78.23 The H2O solubility experiments in albitic and rhyolitic melts confirm the corrections determined using the NaCl calibration method. Moreover, because these experiments are performed at temperatures higher than those used for NaCl calibration, they demonstrate that the pressure correction is not affected by temperature in the range 800-1000 degrees C. The accuracy of the pressure estimate associated with the calibration methods is +/- 25 MPa. The major advantage of using the new assemblies is that low pressure experiments, which require rapid heating and quenching rates (e.g. volcanic and hydrothermal systems), can be performed with the same ease and precision as standard high pressure experiments for which piston cylinder is routinely used. 

  • 106.
    Mathieu, Lucie
    et al.
    Univ Quebec Chicoutimi, CONSOREM, Chicoutimi, PQ G7H 2B1, Canada.;Uppsala Univ, Dept Earth Sci, CEMPEG, S-75236 Uppsala, Sweden..
    Burchardt, Steffi
    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.
    Krumbholz, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Delcamp, Audray
    Vrije Univ Brussel, Fac Sci, Dept Geog, B-1050 Brussels, Belgium..
    Geological constraints on the dynamic emplacement of cone-sheets - The Ardnamurchan cone-sheet swarm, NW Scotland2015Ingår i: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 80, s. 133-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cone-sheets are a significant constituent of many central volcanoes, where they contribute to volcano growth by intrusion and through flank eruptions, although the exact emplacement mechanisms are still controversially discussed. In particular, it is not yet fully resolved whether cone-sheets propagate as magma-driven, opening-mode fractures or as shear fractures, and to what extent pre-existing host-rock structures and different stress fields influence cone-sheet emplacement. To shed further light on the role of these parameters in cone-sheet emplacement, we use detailed field and remote sensing data of the classic Ardnamurchan cone-sheet swarm in NW-Scotland, and we show that the cone-sheets primarily propagated as opening-mode fractures in the sigma(1)-sigma(2) plane of the volcanic stress field. In addition, more than one third of the Ardnamurchan cone-sheet segments are parallel to lineaments that form a conjugate set of NNW and WNW striking fractures and probably reflect the regional NW SE orientation of sigma(1) during emplacement in the Palaeogene. Cone-sheets exploit these lineaments within the NE and SW sectors of the Ardnamurchan central complex, which indicates that the local volcanic stress field dominated during sheet propagation and only allowed exploitation of host-rock discontinuities that were approximately parallel to the sheet propagation path. In addition, outcrop-scale deflections of cone-sheets into sills and back into cone-sheets (also referred to as "staircase" geometry) are explained by the interaction of stresses at the propagating sheet tip with variations in host-rock strength, as well as the influence of sheet-induced strain. As a consequence, cone-sheets associated with sill-like segments propagate as mixed-mode I/II fractures. Hence, cone-sheet emplacement requires a dynamic model that takes into account stress fields at various scales and the way propagating magma interacts with the host rock and its inherent variations in rock strength.

  • 107. Mathieu, Lucie
    et al.
    de Vries, Benjamin van Wyk
    Holohan, Eoghan
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Trinity Coll Dublin, Dept Geol, Dublin 2, Ireland .
    Dykes, cups, saucers and sills: analogue experiments on magma intrusion into brittle rocks2008Ingår i: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 271, nr 1-4, s. 1-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magma is transported in the crust by blade-like intrusions such as dykes, sills, saucers, and also collects in thicker laccoliths, lopoliths and plutons. Recently, the importance and great number of shallow (< ;5 km) saucer-shaped intrusions has been recognized. Lopoliths and cup-shaped intrusions have also been reported in many geological contexts. Our field observations indicate that many intrusions, especially those emplaced into breccias or fractured rocks, have bulging, lobate margins and have shear faults at their bulbous terminations. Such features suggest that magma can propagate along a self-induced shear fault rather than a hydraulic tension-fracture. To investigate this we use analogue models to explore intrusion propagation in a brittle country rock. The models consist of the injection of analogue magma (honey or Golden syrup) in a granular material (sand or sieved ignimbrite) that is a good analogue for brittle or brecciated rocks. These models have the advantage (over other models that use gelatin) to well represent the properties of brittle materials by allowing both shear-faults and tension fractures to be produced at suitable stresses. In our experiments we mainly obtain vertical dykes and inverted-cone like structures that we call cup-shaped intrusions. Dykes bifurcate into cup-shaped intrusions at depths depending on their viscosity. All cup-shaped intrusions uplift a central block. By injecting against a vertical glass plate we obtain detailed observations of the intrusion propagation style. We observe that dykes commonly split and produce cup-shaped intrusions near the surface and that shear zone-related intrusions develop at the dyke tip. We conclude that many dykes propagate as a viscous indenter resulting from shear failure of host rock rather than tensional hydraulic fracturing of host rocks. The shear propagation model provides an explanation for the shape and formation of cup-shaped intrusions, saucer-sills and lopoliths.

  • 108. Mathieu, Lucie
    et al.
    de Vries, Benjamin van Wyk
    Mannessiez, Claire
    Mazzoni, Nelly
    Savry, Cecile
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    The structure and morphology of the Basse Terre Island, Lesser Antilles volcanic arc2013Ingår i: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 75, nr 3, s. 700-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Basse Terre Island is made up of a cluster of composite volcanoes that are part of the Lesser Antilles volcanic arc. The morphology of these volcanoes and the onshore continuation of the grabens and strike-slip faults that surround the island are poorly documented due to erosion and rainforest cover. Therefore, we conducted a morphological analysis of the island using Digital Elevation Model (DEM) data integrated with field observations to document erosional, constructional, and deformational processes. A DEM-based analysis of 1,249 lineaments and field structural measurements of 16 normal faults, 3,741 veins and fractures, and 46 dykes was also carried to document the structures that predominate in sub-surface rocks. The results indicate that the over 1-My-old and elongated Northern Chain volcano, which makes up the northern half of the island, was built by high eruption rates and/or a low viscosity magma injected along the N-S to NNW-SSE-striking extensional structures formed by the flexure of the lithosphere by the overall subduction regime. After 1 Ma, the southern half of the island was shaped by an alignment of conical volcanoes, likely built by a more viscous magma type that was guided by the NW-SE-striking Montserrat-Bouillante strike-slip fault system. These N to NNW and NW structural directions are however poorly expressed onshore, possibly due to slow slip motion. The sub-surface rocks mostly contain E-W-striking structures, which have likely guided the many flank instabilities documented in the studied area, and guide hydrothermal fluids and shallow magmatic intrusions. These structures are possibly part of the E-W-striking Marie-Gallante offshore graben.

  • 109. Mathieu, Lucie
    et al.
    de Vries, Benjamin van Wyk
    Pilato, Martin
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    The interaction between volcanoes and strike-slip, transtensional and transpressional fault zones: Analogue models and natural examples2011Ingår i: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 33, nr 5, s. 898-906Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Regional strike-slip faulting can control magma movements, deform volcanoes and may destabilise their flanks. The aim of this study is to address this problem by comparing two natural examples, Basse Terre Island volcanoes, Lesser Antilles and Maderas volcano, Nicaragua, with analogue experiments. The field and remote sensing analyses of their structures reveal that Guadeloupe volcanoes, which developed in a 145 degrees-striking sinistral transtensional fault zone, are dominantly fractured in a 090 degrees-120 degrees direction, which is parallel to the maximum principal horizontal stress and to the elongation direction of the summit graben of analogue models. This graben is bordered by the Sigmoid-I fault, or Y shear structure, and has facilitated the formation of the Beaugendre and Vieux-Habitants valleys by faulting, erosion or collapse. This structure has also influenced the injection of dykes and the transport of hydrothermal fluids. The comparison of Maderas volcano with the analogue models confirms that the volcano has developed parallel to a 135 degrees-striking dextral transtensional fault zone and is also gravitationally spreading over a weak substratum. This study illustrates how regional strike-slip faulting and gravitational loading combine to produce a clear set of structures within volcanic edifices, which control the location of intrusive zones, hydrothermal activity and collapse directions.

  • 110. Meade, F. C.
    et al.
    Chew, D. M.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Ellam, R. M.
    Page, L. M.
    Magma Ascent along a Major Terrane Boundary: Crustal Contamination and Magma Mixing at the Drumadoon Intrusive Complex, Isle of Arran, Scotland2009Ingår i: Journal of Petrology, ISSN 0022-3530, E-ISSN 1460-2415, Vol. 50, nr 12, s. 2345-2374Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The composite intrusions of Drumadoon and An Cumhann crop outon the SE coast of the Isle of Arran, Scotland and form partof the larger British and Irish Palaeogene Igneous Province,a subset of the North Atlantic Igneous Province. The intrusions(shallow-level dykes and sills) comprise a central quartz–feldspar-phyricrhyolite flanked by xenocryst-bearing basaltic andesite, withan intermediate zone of dark quartz–feldspar-phyric dacite.New geochemical data provide information on the evolution ofthe component magmas and their relationships with each other,as well as their interaction with the crust through which theytravelled. During shallow-crustal emplacement, the end-membermagmas mixed. Isotopic evidence shows that both magmas werecontaminated by the crust prior to mixing; the basaltic andesitemagma preserves some evidence of contamination within the lowercrust, whereas the rhyolite mainly records upper-crustal contamination.The Highland Boundary Fault divides Arran into two distinctterranes, the Neoproterozoic to Early Palaeozoic Grampian Terraneto the north and the Palaeozoic Midland Valley Terrane to thesouth. The Drumadoon Complex lies within the Midland ValleyTerrane but its isotopic signatures indicate almost exclusiveinvolvement of Grampian Terrane crust. Therefore, although themagmas originated at depth on the northern side of the HighlandBoundary Fault, they have crossed this boundary during theirevolution, probably just prior to emplacement.

  • 111.
    Meade, F. C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Ellam, R. M.
    Freda, C.
    Font, L.
    Donaldson, C. H.
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Bimodal magmatism produced by progressively inhibited crustal assimilation2014Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, s. 4199-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of bimodal (mafic-felsic) rock suites is a fundamental question in volcanology. Here we use major and trace elements, high-resolution Sr, Nd and Pb isotope analyses, experimental petrology and thermodynamic modelling to investigate bimodal magmatism at the iconic Carlingford Igneous Centre, Ireland. We show that early microgranites are the result of extensive assimilation of trace element-enriched partial melts of local metasiltstones into mafic parent magmas. Melting experiments reveal the crust is very fusible, but thermodynamic modelling indicates repeated heating events rapidly lower its melt-production capacity. Granite generation ceased once enriched partial melts could no longer form and subsequent magmatism incorporated less fertile restite compositions only, producing mafic intrusions and a pronounced compositional gap. Considering the frequency of bimodal magma suites in the North Atlantic Igneous Province, and the ubiquity of suitable crustal compositions, we propose 'progressively inhibited crustal assimilation' (PICA) as a major cause of bimodality in continental volcanism.

  • 112.
    Meade, Fiona C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    A tale of two magmasIngår i: Earth Science IrelandArtikel i tidskrift (Refereegranskat)
  • 113.
    Meade, Fiona
    et al.
    University of Glasgow.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Chew, David M.
    Department of Geology, Trinity College Dublin, Dublin 2, Ireland .
    Meighan, Ian
    Department of Geology, Trinity College Dublin, Dublin 2, Ireland .
    Cooper, Mark
    Geological Survery of N. Ireland.
    Emeleus, C. Henry
    Department of Earth Sciences, University of Durham, Durham DHI 3LE, UK.
    Caldera Controversy at the Ring of Gullion, County Down2010Ingår i: Earth Science Ireland, ISSN 1753-5271, Vol. 8, s. 12-15Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 114. Meyer, R.
    et al.
    Nicoll, G.R.
    Hertogen, J.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Ellam, R.
    Emeleus, H.
    Trace element and isotope constraints on crustal anatexis byupwelling mantle melts in the North Atlantic Igneous Province: anexample from the Isle of Rum, NW Scotland2009Ingår i: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, nr 3, s. 382-399Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sr and Nd isotope ratios, together with lithophile trace elements, have been measured in arepresentative set of igneous rocks and Lewisian gneisses from the Isle of Rum in order to unravel thepetrogenesis of the felsic rocks that erupted in the early stages of Palaeogene magmatism in the NorthAtlantic Igneous Province (NAIP). The Rum rhyodacites appear to be the products of large amountsof melting of Lewisian amphibolite gneiss. The Sr and Nd isotopic composition of the magmas canbe explained without invoking an additional granulitic crustal component. Concentrations of the traceelement Cs in the rhyodacites strongly suggests that the gneiss parent rock had experienced Cs and Rbloss prior to Palaeogene times, possibly during a Caledonian event. This depletion caused heterogeneitywith respect to 87Sr/86Sr in the crustal source of silicic melts. Other igneous rock types on Rum (dacites,early gabbros) are mixtures of crustalmelts and and primarymantle melts. Forward Rare Earth Elementmodelling shows that late stage picritic melts on Rum are close analogues for the parent melts of theRum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss.These primary mantle melts have close affinities to Mid-Oceanic Ridge Basalts (MORB), whose traceelement content varies from slightly depleted to slightly enriched. Crustal anatexis is a common processin the rift-to-drift evolution during continental break-up and the formation of Volcanic Rifted Marginssystems. The ‘early felsic–later mafic’ volcanic rock associations from Rum are compared to similarassociations recovered from the now-drowned seaward-dipping wedges on the shelf of SE Greenlandand on the Vøring Plateau (Norwegian Sea). These three regions show geochemical differences thatresult from variations in the regional crustal composition and the depth at which crustal anatexis took place.

  • 115.
    Muir, Duncan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Saunders, Kate E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Chemcial fingerprinting of crystal populations from Sekincau, Marapi and Sinabung volcanoes, Sumatra2014Konferensbidrag (Refereegranskat)
  • 116.
    Muir, Duncan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Utami, P.
    Humaida, Hanik
    Warmada, I.W.
    Ellis, B.S.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Gertisser, R.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Saunders, K.E.
    Vandani, C.P.K.
    The sub-Plinian eruption of Kelut volcano, 13th February 20142014Konferensbidrag (Refereegranskat)
  • 117. Nicoll, Graeme R.
    et al.
    Holness, Marian B.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Donaldson, Colin H.
    Holohan, Eoghan P.
    Emeleus, C. Henry
    Chew, David
    Early mafic magmatism and crustal anatexis on the Isle of Rum: evidence from the Am Mam intrusion breccia2009Ingår i: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, nr 3, s. 368-381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Rum Igneous Centre comprises two early marginal felsic complexes (the Northern Marginal Zone and the Southern Mountains Zone), along with the later central ultrabasic-basic layered intrusions. These marginal complexes represent the remnants of near-surface to eruptive felsic magmatism associated with caldera collapse, examples of which are rare in the North Atlantic Igneous Province. Rock units include intra-caldera collapse breccias, rhyolitic ignimbrite deposits and shallow-level felsic intrusions, as well the enigmatic 'Am Mam intrusion breccia'. The latter comprises a dacitic matrix enclosing lobate basaltic inclusions (similar to 1-15 cm) and a variety of clasts, ranging from millimetres to tens of metres in diameter. These clasts comprise Lewisian gneiss, Torridonian sandstone and coarse gabbro. Detailed re-mapping of the Am Mam intrusion breccia has shown its timing of emplacement as syn-caldera, rather than pre-caldera as previously thought. Textural analysis of entrained clasts and adjacent, uplifted country rocks has revealed their thermal metamorphism by early mafic intrusions at greater depth than their present structural position. These findings provide a window into the evolution of the early mafic magmas responsible for driving felsic magmatism on Rum. Our data help constrain some of the physical parameters of this early magma-crust interaction and place it within the geochemical evolution of the Rum Centre.

  • 118.
    Pedroza, Kirsten
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Cachao, Mario
    Ferreira, Jose
    Carracedo, Juan Carlos
    Soler, Vincente
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Meade, Fiona C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Canary Island volcanism: fracture induced or mantle plume related?2014Konferensbidrag (Refereegranskat)
  • 119.
    Pedroza, Kirsten
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Meade, Fiona C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carracedo, J.C.
    Klügel, A.
    Harris, C.
    Wiesmaier, S.
    Berg, Sylvia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Origin and significance of the 2011 El Hierro xeno-pumice2014Konferensbidrag (Refereegranskat)
  • 120.
    Pedroza, Kirsten
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Meade, Fiona C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Klügel, A.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carraedo, Juan C.
    Harris, Chris
    Wiesmaier, Sebastian
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Significance of 2011/201 El Hierro xeno-pumice2014Konferensbidrag (Refereegranskat)
  • 121. Perez-Torrado, F. J.
    et al.
    Carracedo, J. C.
    Rodriguez-Gonzalez, A.
    Soler, V.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Wiesmaier, S.
    La erupción submarina de La Restinga en la islade El Hierro, Canarias: Octubre 2011-Marzo 20122012Ingår i: Estudios Geológicos, ISSN 0367-0449, Vol. 68, nr 1, s. 5-27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first signs of renewed volcanic activity at El Hierro began in July 2011 with the occurrence of abundant, low-magnitude earthquakes. The increasing seismicity culminated on October 10, 2011, with the onset of a submarine eruption about 2 km offshore from La Restinga, the southernmost village on El Hierro. The analysis of seismic and deformation records prior to, and throughout, the eruption allowed the reconstruction of its main phases: 1) ascent of magma and migration of hypocentres from beneath the northern coast (El Golfo) towards the south rift zone, close to La Restinga, probably marking the hydraulic fracturing and the opening of the eruptive conduit; and 2) onset and development of a volcanic eruption indicated by sustained and prolonged harmonic tremor whose intensity varied with time. The features monitored during the eruption include location, depth and morphological evolution of the eruptive source and emission of floating volcanic bombs. These bombs initially showed white, vesiculated cores (originated by partial melting of underlying pre-volcanic sediments upon which the island of El Hierro was constructed) and black basanite rims, and later exclusively hollow basanitic lava balloons. The eruptive products have been matched with a fissural submarine eruption without ever having attained surtseyan explosiveness. The eruption has been active for about five months and ended in March 2012, thus becoming the second longest reported historical eruption in the Canary Islands after the Timanfaya eruption in Lanzarote (1730-1736). This eruption provided the first opportunity in 40 years to manage a volcanic crisis in the Canary Islands and to assess the interpretations and decisions taken, thereby gaining experience for improved management of future volcanic activity. Seismicity and deformation during the eruption were recorded and analysed by the Instituto Geografico Nacional (IGN). Unfortunately, a lack of systematic sampling of erupted pyroclasts and lavas, as well as the sporadic monitoring of the depth and growth of the submarine vent by deployment of a research vessel, hampered a comprehensive assessment of hazards posed during volcanic activity. Thus, available scientific data and advice were not as high quality as they could have been, thereby limiting the authorities in making the proper decisions at crucial points during the crisis. The response in 2011-12 to the El Hierro eruption has demonstrated that adequate infrastructure and technical means exist in the Canary Islands for the early detection of potential eruptive hazards. However, it also has taught us that having detailed emergency management plans may be of limited value without an accompanying continuous, well-integrated scientific monitoring effort (open to national and international collaboration) during all stages of an eruption.

  • 122.
    Perez-Torrado, F.J.
    et al.
    Grupo investigación GEOVOL, Dpto. de Física, Universidad de Las Palmas de Gran Canaria, España.
    Carracedo, J.C.
    Grupo investigación GEOVOL, Dpto. de Física, Universidad de Las Palmas de Gran Canaria, España.
    Rodíguez-Gonzáles, A.
    Grupo investigación GEOVOL, Dpto. de Física, Universidad de Las Palmas de Gran Canaria, España.
    Soler, V.
    Estación Volcanológica de Canarias, IPNA-CSIC, La Laguna, Tenerife, España.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Wiesmeier, S.
    Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universität, Munich, Germany.
    The submarine erupton of La Restinga (El Hierro, Canary Islands):: October 2011 - March 20122012Ingår i: Estudios Geológicos, Vol. 68, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [es]

    Los primeros indicios de una posible erupción volcánica en El Hierro se percibieron a partir de julio de 2011 en forma de sismos de baja intensidad pero anormalmente numerosos. La intensificación de la sismicidad culminó con el inicio de la erupción submarina el 10 de octubre de 2011 a unos 2 km al sur de La Restinga. La sismicidad y deformación del terreno que precedieron y acompañaron a esta erupción han permitido reconstruir las principales fases de actividad volcánica: 1) generación y ascenso del magma con migración de los hipocentros sísmicos desde el norte, en el Golfo, hasta el rift sur, en La Restinga, marcando la apertura hidráulica del conducto magmático; y 2) inicio y continuidad de la erupción volcánica evidenciada por un tremor armónico continuo de intensidad variable en el tiempo. Las características observadas a lo largo de la erupción, principalmente localización, profundidad y evolución morfológica del foco emisor, así como emisión de materiales volcánicos flotantes, inicialmente con un núcleo blanco poroso (procedentes de la fusión parcial de sedimentos de la capa superior de la corteza oceánica anteriores a la construcción del edificio insular de El Hierro) envuelto por una corteza basanítica y después huecas (lava balloons), se han correspondido con una erupción submarina fisural profunda sin que nunca hayan intervenido mecanismos más explosivos tipo surtseyano. La erupción se mantuvo activa durante unos cinco meses, dándose por finalizada en marzo del 2012, convirtiéndose de este modo en la segunda erupción histórica más longeva de Canarias después de la de Timanfaya (1730-36) en Lanzarote. Esta erupción ha supuesto la primera oportunidad en 40 años de gestionar una crisis volcánica en Canarias y de analizar las observaciones e interpretaciones y las decisiones adoptadas, con objeto de mejorar la gestión de futuras crisis volcánicas. El Instituto Geográfico Nacional (IGN) se encargó de adquirir y analizar la información sísmica y de deformación durante todo el proceso. Sin embargo, no se dispuso inicialmente de un barco oceanográfico que realizara estudios sistemáticos de la profundidad y progresión de la erupción, así como de toma de muestras de los materiales emitidos (piroclastos y lavas), elementos claves para la determinación de la peligrosidad eruptiva. Estas deficiencias en el seguimiento científico del proceso eruptivo dificultaron en algunos momentos la toma de decisiones de protección civil. El análisis de la crisis ha puesto de manifiesto que, aunque se disponga de una infraestructura técnica adecuada para la detección temprana de crisis eruptivas en el archipiélago, de poco valen las medidas administrativas planificadas sin un seguimiento científico continuo e integrador del proceso eruptivo, abierto a la colaboración científica nacional e internacional.

  • 123. Person, K.P.
    et al.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Weis, Franz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Persson, L.
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Skelton, A.
    The Grängesberg apatite-iron oxide deposit2013Rapport (Övrigt vetenskapligt)
  • 124.
    Peters, Stefan T. M.
    et al.
    Geowissenschaftliches Zentrum Georg August Univ t, Abt Isotopengeol, Goldschmidtstr 1, D-37077 Gottingen, Germany.;Vrije Univ Amsterdam, Fac Aard Levenswetenschappen, Boelelaan 1085, NL-1081 HV Amsterdam, Netherlands..
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Weis, Franz A.
    Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden..
    Dallai, Luigi
    CNR, Ist Geosci & Georisorse, Via Moruzzi 1, I-56124 Pisa, Italy..
    Chadwick, Jane P.
    Vrije Univ Amsterdam, Fac Aard Levenswetenschappen, Boelelaan 1085, NL-1081 HV Amsterdam, Netherlands.;Trin Coll Dublin, Sci Gallery, Pearse St, Dublin, Ireland..
    Schulz, Bernhard
    TU Bergakademie Freiberg, Inst Mineral, Brennhausgasse 14, D-09599 Freiberg, Saxony, Germany..
    Amphibole megacrysts as a probe into the deep plumbing system of Merapi volcano, Central Java, Indonesia2017Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 172, nr 4, artikel-id 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amphibole has been discussed to potentially represent an important phase during early chemical evolution of arc magmas, but is not commonly observed in eruptive arc rocks. Here, we present an in-depth study of metastable calcic amphibole megacrysts in basaltic andesites of Merapi volcano, Indonesia. Radiogenic Sr and Nd isotope compositions of the amphibole megacrysts overlap with the host rock range, indicating that they represent antecrysts to the host magmas rather than xenocrysts. Amphibolebased barometry suggests that the megacrysts crystallised at pressures of >500 MPa, i.e., in the mid-to lower crust beneath Merapi. Rare-earth element concentrations, in turn, require the absence of magmatic garnet in the Merapi feeding system and, therefore, place an uppermost limit for the pressure of amphibole crystallisation at ca. 800 MPa. The host magmas of the megacrysts seem to have fractionated significant amounts of amphibole and/or clinopyroxene, because of their low Dy/Yb ratios relative to the estimated compositions of the parent magmas to the megacrysts. The megacrysts' parent magmas at depth may thus have evolved by amphibole fractionation, in line with apparently coupled variations of trace element ratios in the megacrysts, such as e.g., decreasing Zr/Hf with Dy/Yb. Moreover, the Th/U ratios of the amphibole megacrysts decrease with increasing Dy/Yb and are lower than Th/U ratios in the basaltic andesite host rocks. Uranium in the megacrysts' parent magmas, therefore, may have occurred predominantly in the tetravalent state, suggesting that magmatic fO(2) in the Merapi plumbing system increased from below the FMQ buffer in the mid-to-lower crust to 0.6-2.2 log units above it in the near surface environment. In addition, some of the amphibole megacrysts experienced dehydrogenation (H-2 loss) and/or dehydration (H2O loss), as recorded by their variable H2O contents and D/H and Fe3+/Fe2+ ratios, and the release of these volatile species into the shallow plumbing system may facilitate Merapi's often erratic eruptive behaviour.

  • 125.
    Pérez-Torrado, Francisco José
    et al.
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Rodríguez González, Alejandro
    Grupo de Investigación GEOVOL, Dpto. de Física, Universidad de Las Palmas de Gran Canaria, Spain .
    Rodríguez Badiola, E.
    Dpto. Geología, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.
    Paris, Raphael
    Géolab UMR 6042 CNRS, Clermont-Ferrand, France.
    Troll, Valentin
    Clarke, Hilary
    Serengeti Resources Inc. SIR: TSX-V, Vancouver, 34S:FSE, Canada.
    Wiesmaier, Sebastian
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Eruptive Styles at the Teide Volcanic Complex2013Ingår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 213-231Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The wide variety of volcanic products composing the Teide VolcanicComplex (TVC) reflects an unusual assemblage of eruptive styles, with awide range of phenomena represented and only plinian and phreato-plinian styles truly lacking. This diversity is due to spatial and temporalvariations in magma composition (mafic magmas of the rift zones andfelsic magmas of the central edifice), variable magmatic volatile contentsand the interaction of magma with external water (snow, groundwater,etc.). Overall, strombolian eruptions are the most frequent eruptive styleat the TVC. Explosive eruptions of felsic material tend to be of lowvolume, for example, the largest explosive event during the Holocene, Montaña Blanca (ca. 2 ka), produced*0.2 km3DRE of phonoliticpumice during an eruptive sequence that reached explosivity of sub-plinian magnitude. Examples of phreatomagmatic activity (surge depos-its) have been described both on the northern flanks of Teide volcano aswell as from the summit area of Pico Viejo volcano. Until now moststudies on volcanic hazard assessment have focussed on ash fall and lavaflow hazards in the Canary Islands, but phreatomagmatic eruptions andtheir potential effects may have to be seriously considered as well.

  • 126. Sahlström, F
    et al.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, SE-75128 Uppsala, Sweden..
    Harris, C.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    O and C isotope study of Bastnäs-type rare earth element mineralisation, Bergslagen, Sweden2015Konferensbidrag (Refereegranskat)
  • 127.
    Samrock, Lisa K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jensen, Max J.
    Burchardt, Steffi
    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.
    Mattsson, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Geiger, Harri
    3D modelling of the Tejeda Caldera cone-sheet swarm, Gran Canaria, Canary Islands, Spain2015Ingår i: Geophysical Research Abstracts, 2015, Vol. 17, artikel-id EGU2015-958Konferensbidrag (Övrigt vetenskapligt)
  • 128.
    Saunder, Kate E.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Muir, Duncan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Petrogenesis of Sumatra’s andesite volcanoes2014Konferensbidrag (Refereegranskat)
  • 129.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Blythe, Lara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harris, C.
    Berg, Sylvia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Hilton, D.R.
    Freda, C.
    Reconstructing the plumbing system of Krakatau volcano2014Konferensbidrag (Refereegranskat)
  • 130.
    Troll, Valentin
    et al.
    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.
    Burchardt, Steffi
    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.
    Carracedo, Juan-Carlos
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Meade, Fiona C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Soler, Vicente
    Estacion Volcanologica de Canarias, IPNA-CSIC, La Laguna, Tenerife, Spain.
    Cachao, Mario
    University of Lisbon, Faculty of Sciences, Instituto Dom Luiz (Geology), Portugal.
    Ferreira, Jorge
    University of Lisbon, Faculty of Sciences, Instituto Dom Luiz (Geology), Portugal.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Nannofossils: the smoking gun for the Canarian hotspot2015Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, nr 4, s. 137-145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of volcanism in the Canary Islands has been a matter of controversy for several decades. Discussions have hinged on whether the Canaries owe their origin to seafloor fractures associated with the Atlas Mountain range or to an underlying plume or hotspot of superheated mantle material. However, the debate has recently come to a conclusion following the discovery of nannofossils preserved in the products of the 2011–2012 submarine eruption at El Hierro, which tell us about the age and growth history of the western-most island of the archipelago. Light coloured, pumice-like ‘floating rocks’ were found on the sea surface during the first days of the eruption and have been shown to contain fragments of pre-island sedimentary strata. These sedimentary rock fragments were picked up by ascending magma and transported to the surface during the eruption, and remarkably retained specimens of pre-island Upper Cretaceous to Pliocene calcareous nannofossils (e.g. coccolithophores). These marine microorganisms are well known biostratigraphical markers and now provide crucial evidence that the westernmost and youngest island in the Canaries is underlain by the youngest sediment relative to the other islands in the archipelago. This finding supports an age progression for the onset of volcanism at the individual islands of the archipeligo. Importantly, as fracture-related volcanism is known to produce non-systematic age-distributions within volcanic alignments, the now-confirmed age progression corroberates to the relative motion of the African plate over an underlying mantle plume or hotspot as the cause for the present-day Canary volcanism.

  • 131.
    Troll, Valentin
    et al.
    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 Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Budd, David
    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.
    Schwarzkopf, L.M.
    Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.2015Ingår i: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, nr 1, s. 137-166Artikel i tidskrift (Refereegranskat)
  • 132.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Budd, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Schwarzkopf, L.M.
    Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia2014Konferensbidrag (Refereegranskat)
  • 133.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Blythe, Lara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harris, C.
    Berg, Sylvia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Hilton, D.R.
    Freda, C.
    Magma storage at Krakatau volcanic complex2014Konferensbidrag (Refereegranskat)
  • 134.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester Muños
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harris, C.
    Dept. of Geological Science, University of Cape Town, Rondebosch 7701, South Africa.
    Chadwick, J.P.
    Dept of Petrology (FALW), De Boelelaan 1085, Amsterdam, The Netherlands.
    Gertisser, R.
    School of Physical and Geographical Sciences, Keele University, Keele, ST5 5BG, UK.
    Scharzkopf, L.M.
    GeoDocCon, Unterpferdt 8, 95176 Konradsreuth, Germany.
    Borisova, A.Y.
    Observatoire Midi-Pyrénées, Université Toulouse, 14 Avenue E. Belin, 31400 Toulouse, France.
    Bindeman, I.N.
    Dept. of Geological Sciences, 1272 University of Oregon, Eugene, OR 97403, United States.
    Sumarti, S.
    Volcano Investigation and Technology Development Institution, Yogyakarta, Indonesia.
    Preece, K.
    School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
    Magmatic differentiation processes at Merapi Volcano: inclusion petrology and oxygen isotopes2013Ingår i: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 261, nr SI, s. 38-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Indonesian volcano Merapi is one of the most hazardous volcanoes on the planet and is characterised by periods of active dome growth and intermittent explosive events. Merapi currently degasses continuously through high temperature fumaroles and erupts basaltic-andesite dome lavas and associated block-and-ash-flows that carry a large range of magmatic, coarsely crystalline plutonic, and meta-sedimentary inclusions. These inclusions are useful in order to evaluate magmatic processes that act within Merapi's plumbing system, and to help an assessment of which phenomena could trigger explosive eruptions. With the aid of petrological, textural, and oxygen isotope analysis we record a range of processes during crustal magma storage and transport, including mafic recharge, magma mixing, crystal fractionation, and country rock assimilation. Notably, abundant calc-silicate inclusions (true xenoliths) and elevated δ18O values in feldspar phenocrysts from 1994, 1998, 2006, and 2010 Merapi lavas suggest addition of limestone and calc-silicate materials to the Merapi magmas. Together with high δ13C values in fumarole gas, crustal additions to mantle and slab-derived magma and volatile sources are likely a steady state process at Merapi. This late crustal input could well represent an eruption trigger due to sudden over-pressurisation of the shallowest parts of the magma storage system independently of magmatic recharge and crystal fractionation. Limited seismic precursors may be associated with this type of eruption trigger, offering a potential explanation for the sometimes erratic behaviour of Merapi during volcanic crises.

  • 135.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Delcamp, Audray
    Department of Geography, Vrije Universiteit Brussels, Brussels 1050, Belgium.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa.
    van Wyk de Vries, Benjamin
    Laboratoire Magmas et Volcans, Université Blaise-Pascal, 63038 Clermont-Ferrand, France.
    Petronis, Michael S.
    Environmental Geology Natural Resource Management Department, New Mexico Highlands University, Las Vegas, New Mexico 87701, U.S.A.
    Pérez-Torrado, Francisco José
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Chadwick, Jane P.
    Science Gallery, Trinity College Dublin, Dublin 2, Ireland.
    Barker, Abigail K.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Wiesmaier, Sebastian
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Pre-Teide Volcanic Activity on the Northeast Volcanic Rift Zone2013Ingår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 75-92Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The northeast rift zone of Tenerife (NERZ) presents a partially eroded volcanic rift that offers a superb opportunity to study the structure and evolution of oceanic rift zones. Field data, structural observations, isotopic dating, magnetic stratigraphy, and isotope geochemistry have recently become available for this rift and provide a reliable temporal framework for understanding the structural and petrological evolution of the entire rift zone. The NERZ appears to have formed in several major pulses of activity with a particularly high production rate in the Pleistocene (ca. 0.99 and 0.56 Ma). The rift underwent several episodes of flank creep and eventual catastrophic collapses driven by intense intrusive activity and gravitational adjustment. Petrologically, a variety of mafic rock types, including crystal-rich ankaramites, have been documented, with most samples isotopically typical of the “Tenerife signal”. Some of the NERZ magmas also bear witness to contamination by hydrothermally altered components of the island edifice and/or sediments. Isotope geochemistry furthermore points to the generation of the NERZ magmas from an upwelling column of mantle plume material mixed with upper asthenospheric mantle. Finally, persistent isotopic similarity through time between the NERZ and the older central edifices on Tenerife provides strong evidence for a genetic link between Tenerife’s principal volcanic episodes.

  • 136.
    Troll, Valentin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Klügel, A
    3Institute of Geosciences, University of Bremen, Germany.
    Longpré, M.-A
    Dept. of Earth and Planetary Sciences, McGill University, Canada.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances
    Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockhom, Sweden..
    Carracedo, J.C
    Dept. of Physics (Geology), GEOVOL, University of Las Palmas, Gran Canaria, Spain.
    Wiesmaier, S
    Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Kueppers, U
    Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Blythe, Lara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Hansteen, T. H
    Leibniz-Institute for Oceanography, IFM-GEOMAR, Kiel, Germany.
    Freda, Carmela
    Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy.
    Budd, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, Ester
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jonsson, E
    Geological Survey of Sweden, Uppsala, Sweden.
    Meade, Fiona
    School of Geographical and Earth Sciences, University of Glasgow, UK.
    Harris, Chris
    Department of Geological Sciences, University of Cape Town, South Africa.
    Berg, Sylvia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Mancini, Lucia
    SYRMEP Group, Sincrotrone Trieste S.C.p.A, Basovizza, Trieste, Italy.
    Polacci, M
    Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, 56124 Pisa, Italy.
    Pedroza, Kirsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption2012Ingår i: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 3, nr 1, s. 97-110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 137. Troll, Valentin
    et al.
    Nicoll, Graeme R.
    Department of Geology, School of Natural Science, Trinity College Dublin, Dublin 2, Ireland.
    Donaldson, Colin H.
    School of Geosciences, University of St. Andrews, KY16 9AL, UK.
    Emeleus, C. Henry
    Department of Earth Sciences, University of Durham, Durham DHI 3LE, UK.
    Dating the onset of volcanism at the Rum Igneous Centre, NW Scotland2008Ingår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 165, s. 651-659Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Major volcanic activity on the Isle of Rum commenced with the eruption of thick (>100 m) intra-caldera rhyodacite ash-flow sheets fed from steep-sided feeder conduits in the proximity of the Main Ring Fault. Twenty plagioclase phenocrysts of the rhyodacite were analysed using single crystal 40Ar/39Ar laser dating, yielding a mean apparent age of 60.83 ± 0.27 Ma (MSWD=3.65). On an age v. probability plot the feldspars do not, however, show a simple Gaussian distribution, but a major peak at 60.33 ± 0.21 Ma and two smaller shoulders at c. 61.4 Ma and 63 Ma. These older ages are interpreted to represent recycled and largely re-equilibrated feldspars. The age peak at 60.33 ± 0.21 Ma is interpreted to represent the intrusion and eruption age of the rhyodacites. This new age constraint overlaps with that for the ultrabasic intrusion, implying that the latter was already forming at depth and supplying necessary heat during the early felsic activity phase, and quickly thereafter migrated upwards to shallow structural levels and intruded the volcano's earlier deposits. Combined with previously published ages, these new age data highlight an extremely rapid succession of events at the Rum centre, the whole sequence occurring in potentially <500 ka.

  • 138.
    Troll, Valentin R.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Carracedo, Juan Carlos
    Jägerup, Beatrice
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Streng, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    Barker, Abigail
    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.
    Perez-Torrado, Francisco
    Rodriguez-Gonzalez, Alejandro
    Geiger, Harri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Volcanic particles in agriculture and gardening2017Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 33, nr 4, s. 148-154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Volcanic pyroclasts of small size, such as lapilli and small pumice stones, are widely used in agriculture, gardening, and for pot plants as natural inorganic mulch. The technique of using pyroclasts to enhance topsoil stems from the eighteenth century, and specifically from the ad 1730–1736 eruption on Lanzarote. Critical observations on plant development during and after the eruption showed that the vegetation died when buried under a thick layer of lapilli, but grew vigorously when covered thinly. While the agriculture of Lanzarote was restricted to cereals before the eruption, it diversified to many kinds of fruit and vegetables afterwards, including the production of the famous Malvasía wines in the Canaries. The population of Lanzarote doubled in the years after the eruption, from about 5000 in 1730 to near 10 000 in 1768, predominantly as a result of the higher agricultural productivity. This outcome led to widespread use of lapilli and pumice fragments throughout the islands and eventually the rest of the globe. Lapilli and pumice provide vesicle space for moisture to be retained longer within the planting soil, which can create an environment for micro-bacteria to thrive in. Through this route, nutrients from volcanic matter are transported into the surrounding soil where they become available to plant life. The detailed processes that operate within the pyroclasts are less well understood, such as the breakdown of nutrients from the rock matrix and transport into the soil by biological action. Further studies promise significant potential to optimize future agricultural efforts, particularly in otherwise arid areas of the globe.

  • 139.
    Troll, Valentin R
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Chadwick, Jane P.
    Science Gallery, Trinity College Dublin, Dublin.
    Jolis, Ester M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances M.
    Dept. of Geoscience, Swedish Museum of Natural History, Stockholm.
    Hilton, David
    Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, USA .
    Schwarzkopf, Lothar M.
    GeoDocCon, Konradsreuth, Germany.
    Blythe, Lara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Zimmer, Martin
    Helmholtz – Centre Potsdam, GFZ, Potsdam, Germany.
    Crustal volatile release at Merapi volcano; the 2006 earthquake and eruption events2013Ingår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 29, nr 3, s. 96-101Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 140.
    Troll, Valentin R.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Emeleus, C. Henry
    Dept. of Earth Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
    Nicoll, Graeme R.
    Neftex Insights, Halliburton, 97 Jubilee Avenue, Milton Park, Abingdon, Oxfordshire, OX14 4RW, UK.
    Mattsson, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Ellam, Robert M.
    Scottish Universities Environmental Research Centre (SUERC), Scottish Enterprise Technology Park, Rankine Avenue, East Kilbride, G75 0QF, UK.
    Donaldson, Colin H.
    Dept. of Geography and Geosciences, University of St Andrews, North Street, St Andrews, KY16 9AL, UK.
    Harris, Chris
    Dept. of Geological Sciences, University of Cape Town, Rondebosch, 7701 South Africa.
    A large explosive silicic eruption in the British Palaeogene Igneous Province2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Large-volume pyroclastic eruptions are not known from the basalt-dominated British Palaeogene Igneous Province (BPIP), although silicic magmatism is documented from intra-caldera successions in central volcanoes and from small-volume ash-layers in the associated lava fields. Exceptions are the Sgùrr of Eigg (58.7 Ma) and Òigh-sgeir pitchstones in the Inner Hebrides (>30 km apart), which have been conjectured to represent remnants of a single large silicic event. Currently available major element data from these outcrops differ, however, creating a need to test if the two pitchstones are really related. We employ a systematic array of methods ranging from mineralogy to isotope geochemistry and find that samples from the two outcrops display identical mineral textures and compositions, major- and trace elements, and Sr-Nd-Pb-O isotope ratios, supporting that the two outcrops represent a single, formerly extensive, pyroclastic deposit. Available isotope constraints suggest a vent in the Hebridean Terrane and available radiometric ages point to Skye, ~40 km to the North. A reconstructed eruption volume of ≥5km3 DRE is derived, suggesting a VEI 5 event or larger. We therefore argue, contrary to long-held perception, that large-volume silicic volcanism and its associated climatic effects were likely integral to the BPIP during the opening of the North Atlantic.

  • 141.
    Troll, Valentin R.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Hilton, David R.
    Jolis, Ester M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Chadwick, Jane P.
    Blythe, Lara S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Deegan, Frances M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Schwarzkopf, Lothar M.
    Zimmer, Martin
    Crustal CO2 liberation during the 2006 eruption and earthquake events at Merapi volcano, Indonesia2012Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, s. L11302-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-temperature volcanic gas is widely considered to originate from ascending, mantle-derived magma. In volcanic arc systems, crustal inputs to magmatic gases mainly occur via subducted sediments in the mantle source region. Our data from Merapi volcano, Indonesia imply, however, that during the April-October 2006 eruption significant quantities of CO2 were added from shallow crustal sources. We show that prior to the 2006 events, summit fumarole gas delta C-13((CO2)) is virtually constant (delta C-13(1994-2005) = -4.1 +/- 0.3 parts per thousand), but during the 2006 eruption and after the shallow Yogyakarta earthquake of late May, 2006 (M6.4; hypocentres at 10-15 km depth), carbon isotope ratios increased to -2.4 +/- 0.2 parts per thousand. This rise in delta C-13 is consistent with considerable addition of crustal CO2 and coincided with an increase in eruptive intensity by a factor of similar to 3 to 5. We postulate that this shallow crustal volatile input supplemented the mantle-derived volatile flux at Merapi, intensifying and sustaining the 2006 eruption. Late-stage volatile additions from crustal contamination may thus provide a trigger for explosive eruptions independently of conventional magmatic processes.

  • 142.
    Troll, Valentin R.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Weis, Franz A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Swedish Museum Nat Hist, Dept Geosci, Frescativagen 40, S-11418 Stockholm, Sweden.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Geol Survey Sweden, Dept Mineral Resources, Villavagen 18,Box 670, S-75128 Uppsala, Sweden.
    Andersson, Ulf B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Luossavaara Kiirunavaara AB, Res & Dev, FK9, S-98186 Kiruna, Sweden.
    Majidi, Seyed Afshin
    Geol Survey Iran, Meraj St,Azadi Sq, Tehran 1387835841, Iran.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Åbo Akad Univ, Geol & Mineral, Domkyrkotorget 1, SF-20500 Turku, Finland.
    Harris, Chris
    Univ Cape Town, Dept Geol Sci, ZA-7701 Rondebosch, South Africa.
    Millet, Marc-Alban
    Cardiff Univ, Sch Earth & Ocean Sci, Pk Pl, Cardiff CF10 3AT, S Glam, Wales.
    Chinnasamy, Sakthi Saravanan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. NIT Rourkela, Natl Inst Technol Rourkela, Dept Earth & Atmospher Sci, Rourkela 769008, Odisha, India;Indian Inst Technol IIT Bombay, Dept Earth Sci, Mumbai 400076, Maharashtra, India.
    Kooijman, Ellen
    Swedish Museum Nat Hist, Dept Geosci, Frescativagen 40, S-11418 Stockholm, Sweden.
    Nilsson, Katarina P.
    Geol Survey Sweden, Dept Mineral Resources, Villavagen 18,Box 670, S-75128 Uppsala, Sweden;Swedish Minist Enterprise & Innovat, Div Business, Master Samuelsgatan 70, S-10333 Stockholm, Sweden.
    Global Fe-O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores2019Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, artikel-id 1712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Kiruna-type apatite-iron-oxide ores are key iron sources for modern industry, yet their origin remains controversial. Diverse ore-forming processes have been discussed, comprising lowtemperature hydrothermal processes versus a high-temperature origin from magma or magmatic fluids. We present an extensive set of new and combined iron and oxygen isotope data from magnetite of Kiruna-type ores from Sweden, Chile and Iran, and compare them with new global reference data from layered intrusions, active volcanic provinces, and established low-temperature and hydrothermal iron ores. We show that approximately 80% of the magnetite from the investigated Kiruna-type ores exhibit d56Fe and d18O ratios that overlap with the volcanic and plutonic reference materials (> 800 degrees C), whereas similar to 20%, mainly vein-hosted and disseminated magnetite, match the low-temperature reference samples (<= 400 degrees C). Thus, Kiruna-type ores are dominantly magmatic in origin, but may contain latestage hydrothermal magnetite populations that can locally overprint primary hightemperature magmatic signatures.

  • 143. van der Zwan, Froukje M.
    et al.
    Chadwick, Jane P.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Textural history of recent basaltic-andesites and plutonic inclusions from Merapi volcano2013Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 166, nr 1, s. 43-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mt. Merapi in Central Java is one of the most active stratovolcanoes on Earth and is underlain by a multistage plumbing system. Crystal size distribution analyses (CSD) were carried out on recent Merapi basaltic-andesites and co-eruptive magmatic and plutonic inclusions to characterise the crystallisation processes that operate during storage and ascent and to obtain information on respective time scales. The basaltic-andesites exhibit log-linear, kinked-upwards CSD curves for plagioclase and clinopyroxene that can be separated into two main textural populations. Large plagioclase phenocrysts (a parts per thousand yen1.6 mm) make up one population, but correspond to crystals with variable geochemical composition and reflect a period of crystal growth at deep to mid-crustal levels. This population was subsequently influenced by crystal accumulation and the onset of crustal assimilation, including the incorporation of high-Ca skarn-derived xenocrysts. Textural re-equilibration is required for these crystals to form a single population in CSD. A second episode of crystal growth at shallower levels is represented by chemically homogenous plagioclase crystals < 1.6 mm in size. Crustal assimilation is indicated by, for example, oxygen isotopes and based on the CSD data, crystallisation combined with contamination is likely semi-continuous in these upper crustal storage chambers. The CSD data observed in the basaltic-andesite samples are remarkably consistent and require a large-volume steady state magmatic system beneath Merapi in which late textural equilibration plays a significant role. Plagioclase CSDs of co-eruptive magmatic and plutonic inclusions may contain a third crystal population (< 1 mm) not found in the lavas. This third population has probably formed from enhanced degassing of portions of basaltic-andesite magma at shallow crustal levels which resulted in increased crystallinity and basaltic-andesite mush inclusions. A suite of coarse plutonic inclusions is also present that reflects crystallisation and accumulation of crystals in the deep Merapi plumbing system, as deduced from CSD patterns and mineral assemblages.

  • 144.
    Waight, Tod E.
    et al.
    Univ Copenhagen, Geol Sect, Dept Geosci & Nat Resource Management, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark..
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Gamble, John A.
    Victoria Univ Wellington, Sch Geog Environm & Earth Sci, POB 600, Wellington, New Zealand.;Univ Coll Cork, Sch Biol Earth & Environm Sci, Cork, Ireland..
    Price, Richard C.
    Univ Waikato, Fac Sci & Engn, Private Bag 3105, Hamilton, New Zealand..
    Chadwick, Jane P.
    Trinity Coll Dublin, Sci Gallery, Pearse St, Dublin 2, Ireland..
    Hf isotope evidence for variable slab input and crustal addition in basalts and andesites of the Taupo Volcanic Zone, New Zealand2017Ingår i: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 284-285, s. 222-236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crustal contamination complicates the identification of primary mantle-derived magma compositions in continental arcs. However, when crustal processes and components are well characterised, it is possible to extrapolate through continental arc magma compositional arrays towards the Hf and Nd isotope compositions of uncontaminated primary magmas. This is because of the similar behaviour of Hf and Nd during fractional crystallisation and mantle melting, and the subsequent limited variation in Hf/Nd in mantle-derived magmas and in many crustal lithologies, resulting in linear contamination trends for Hf-Nd isotopes. Here we present new Hf isotope data for a selection of volcanic rocks and crustal lithologies from the Taupo Volcanic Zone (TVZ), New Zealand and propose that the scatter in Hf-Nd isotopes indicates heterogeneity in the parental magmas prior to interactions with crustal lithologies. The observed variations likely represent variability in primary magma compositions as a result of different degrees of sediment addition at the slab-wedge interface. Coupled variations in isotopic composition, LILE/HFSE ratios (e.g. Rb/Zr and Ba/La) and SiO2 also clearly indicate that shallower level crustal interactions have occurred. Andesites from Ruapehu Volcano have more consistent parental magma compositions, and require greater amounts of a source sediment contribution. Notably, the compositions of older Ruapehu lavas can be modelled by interactions between mantle-derived magmas and lower crustal granulites, whereas younger lavas have probably interacted more with mid- to shallow crustal meta-sedimentary greywacke-argillite lithologies of the Permian to Cretaceous composite Torlesse Terrane. Hf-Nd isotopic compositions of meta-igneous granulite xenoliths from Mt. Ruapehu are consistent with previous interpretations that they are derived from oceanic crust that underlies the Torlesse meta-sediments. The results indicate that interactions with sediments at both the slab-wedge interface and in the lithosphere must be considered when evaluating trace element and isotopic variations in continental arcs.

  • 145.
    Weis, Franz A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Skogby, Henrik
    Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden..
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Department of Physics (GEOVOL), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Department of Geological Science, Stockholm University, Stockholm, Sweden.
    Dahrén, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Magmatic water contents determined through clinopyroxene: Examples from the Western Canary Islands, Spain2015Ingår i: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 16, nr 7, s. 2127-2146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 146.
    Weis, Franz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jonsson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Högdahl, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harris, C.
    Millet, M.-A.
    Nilsson, K.P.
    Iron and oxygen isotope characteristics of apatite-iron-oxide ores from central Sweden2013Ingår i: Mineral deposit research for a high-tech world, s. 1675-1678Artikel i tidskrift (Refereegranskat)
  • 147.
    Whitley, Sean
    et al.
    Keele Univ, Sch Geog Geol & Environm, Keele ST5 5BG, Staffs, England.
    Gertisser, Ralf
    Keele Univ, Sch Geog Geol & Environm, Keele ST5 5BG, Staffs, England.
    Halama, Ralf
    Keele Univ, Sch Geog Geol & Environm, Keele ST5 5BG, Staffs, England.
    Preece, Katie
    Swansea Univ, Coll Sci, Dept Geog, Swansea SA2 8PP, W Glam, Wales.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Padjajaran UNPAD, Fac Geol Engn, Bandung, Indonesia.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Crustal CO2 contribution to subduction zone degassing recorded through calc-silicate xenoliths in arc lavas2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 8803Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Interaction between magma and crustal carbonate at active arc volcanoes has recently been proposed as a source of atmospheric CO2, in addition to CO2 released from the mantle and subducted oceanic crust. However, quantitative constraints on efficiency and timing of these processes are poorly established. Here, we present the first in situ carbon and oxygen isotope data of texturally distinct calcite in calc-silicate xenoliths from arc volcanics in a case study from Merapi volcano (Indonesia). Textures and C-O isotopic data provide unique evidence for decarbonation, magma-fluid interaction, and the generation of carbonate melts. We report extremely light delta C-13(PDB) values down to -29.3%o which are among the lowest reported in magmatic systems so far. Combined with the general paucity of relict calcite, these extremely low values demonstrate highly efficient remobilisation of crustal CO2 over geologically short timescales of thousands of years or less. This rapid release of large volumes of crustal CO2 may impact global carbon cycling.

  • 148. Wiesmaier, S.
    et al.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carracedo, J. C.
    Ellam, R. M.
    Bindeman, I.
    Wolff, J. A.
    Bimodality of lavas in the teide-pico viejo succession in tenerife-the role of crustal melting in the origin of recent phonolites2012Ingår i: Journal of Petrology, ISSN 0022-3530, E-ISSN 1460-2415, Vol. 53, nr 12, s. 2465-2495Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Tenerife, lavas of the recent Teide-Pico Viejo central complex show a marked bimodality in composition from initially mafic lavas (200-30 ka) to highly differentiated phonolites (30-0 ka). After this abrupt change, the bimodality of the lavas continued to manifest itself between the now felsic Teide-Pico Viejo central complex and the adjacent, but exclusively mafic, rift zones. Whole-rock trace element fingerprinting distinguishes three compositional groups (mafic, transitional, felsic). Groundmass Sr-Nd-Pb-O and feldspar δ. 18O data demonstrate open-system behaviour for the petrogenesis of the Teide-Pico Viejo felsic lavas by high. 87Sr/. 86Sr ratios of up to 0·7049, uniform. 206Pb/. 204Pb (19·75-19·78), variable. 207Pb/. 204Pb (15·53-15·62) and heterogeneous δ. 18O values (5·43-6·80‰). However, ocean sediment contamination can be excluded because of the low. 206Pb/. 204Pb ratios of North Atlantic sediments. Isotope mixing hyperbolae reproduce the entire Teide-Pico Viejo succession and require an assimilant of predominantly felsic composition. Unsystematic and heterogeneous variation of δ. 18O in fresh and unaltered feldspars across the Teide-Pico Viejo succession indicates magmatic addition of diverse δ. 18O assimilants, altered near surface at high and low temperatures. The best fit for these requirements is provided by nepheline syenite that occurs as fresh or altered lithic blocks in voluminous pre-Teide ignimbrite deposits and is similarly heterogeneous in oxygen isotope composition. Nepheline syenite blocks are considered to represent deep remnants of associated earlier eruptions and were thus available for assimilation at depth. Rare earth element modelling indicates that nepheline syenite needs to be melted in bulk to form a suitable end-member composition. Using this assimilant, energy-constrained assimilation fractional crystallization (EC-AFC) modelling reproduces the bulk of the succession, which leads us to suggest that Teide-Pico Viejo petrogenesis is governed by assimilation and fractional crystallization. Both mixing hyperbolae and EC-AFC models indicate that assimilation is more pronounced for the more felsic lavas. The maximum assimilation is evident in the most strongly differentiated (and the most radiogenic in Sr) lava and computes to &gt;97·8% of the assimilant. This most evolved eruption probably represents nepheline syenite bulk melts that formed spatially decoupled from juvenile material. This study therefore recognizes a wider variability of magmatic differentiation processes at Teide-Pico Viejo than previously thought.

  • 149.
    Wiesmaier, Sebastian
    et al.
    Department of Geology, Trinity College Dublin, 2 College Green, Dublin 2, Ireland.
    Deegan, Frances M
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, Valentin R
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-CSIC, Av. Astrofísica Francisco Sanchez 3, 38206 La Laguna, Tenerife, Spain.
    Chadwick, Jane P
    Department of Petrology (FALW), Vrjie Universiteit, 1081 HV Amsterdam, The Netherlands.
    Chew, David M
    Department of Geology, Trinity College Dublin, 2 College Green, Dublin 2, Ireland.
    Magma mixing in the 1100 AD Montaña Reventada composite lava flow, Tenerife, Canary Islands: Interaction between rift zone and central volcano plumbing systems2011Ingår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 162, nr 3, s. 651-669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zoned eruption deposits commonly show a lower felsic and an upper mafic member, thought to reflect eruption from large, stratified magma chambers. In contrast, the Montaña Reventada composite flow (Tenerife) consists of a lower basanite and a much thicker upper phonolite. A sharp interface separates basanite and phonolite, and chilled margins at this contact indicate the basanite was still hot upon emplacement of the phonolite, i.e. the two magmas erupted in quick succession. Four types of mafic to intermediate inclusions are found in the phonolite. Inclusion textures comprise foamy quenched ones, others with chilled margins and yet others that are physically mingled, reflecting progressive mixing with a decreasing temperature contrast between the end-members. Analysis of basanite, phonolite and inclusions for majors, traces and Sr, Nd and Pb isotopes show the inclusions to be derived from binary mixing of basanite and phonolite end-members in ratios of 2:1 to 4:1. Although, basanite and phonolite magmas were in direct contact, contrasting 206Pb/204Pb ratios show that they are genetically distinct (19.7193(21)–19.7418(31) vs. 19.7671(18)–19.7807(23), respectively). We argue that the Montaña Reventada basanite and phonolite first met just prior to eruption and had limited interaction time only. Montaña Reventada erupted from the transition zone between two plumbing systems, the phonolitic Teide-Pico Viejo complex and the basanitic Northwest rift zone. A rift zone basanite dyke most likely intersected the previously emplaced phonolite magma chamber. This led to eruption of geochemically and texturally unaffected basanite, with the inclusion-rich phonolite subsequently following into the established conduit.

  • 150.
    Wiesmaier, Sebastian
    et al.
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Deegan, Frances
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Chadwick, Jane P.
    Department of Petrology (Falw), Vrije Universiteit, 1081 Hv Amsterdam, The Netherlands.
    Magma Mixing in the 1100 AD Montaña Reventada Composite Lava Flow: Interaction of Rift Zone and Central Complex Magmatism2013Ingår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 191-211Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Zoned eruption deposits frequently show a lower felsic and an upper maficmember, thought to reflect eruption from a large, stratified magmachambers. In contrast, however, the Montaña Reventada composite flow inTenerife consists of a lower basanite and a much thicker upper phonolite. Asharp interface separates the basanite and phonolite, and a chilled margin atthis contact indicates the basanite was still hot upon emplacement of thephonolite, i.e. the two magmas erupted in very quick succession. Threetypes of mafic to intermediate inclusions are found in the phonolite, whichcomprise foamy quenched ones, inclusions with chilled margins and thosethat are physically mingled, reflecting progressive mixing with adecreasing temperature contrast between the end-member magmasinvolved. Analysis of basanite, phonolite and inclusions for majors, tracesand Sr, Nd and Pb isotopes show the inclusions to be derived from binarymixing of basanite and phonolite end-members in ratios of 2:1–4:1.Although basanite and phonolite magmas were erupted in quick succession, contrasting206Pb/204Pb ratios show them to be geneticallydistinct. The Montaña Reventada basanite and phonolite first came intocontact just prior to eruption and had seemingly limited interaction time.Montaña Reventada erupted from the transition zone between twoplumbing systems, the phonolitic Teide-Pico Viejo complex and thebasanitic Northwest rift zone. A rift zone basanite dyke most likelyintersected a previously emplaced phonolite magma pocket, leading toeruption of geochemically and texturally unaffected basanite, followed byinclusion-rich phonolite that exploited the already established conduit.

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