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  • 1.
    Andersson Sundén, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Gustavsson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Hjalmarsson, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacewicz, Marek
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, FREIA.
    Lantz, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Marciniewski, Pawel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Ziemann, Volker
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, FREIA.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Lundén, Karl
    SLU.
    Citizen Science and Radioactivity2019Inngår i: Nuclear Physics News, ISSN 1050-6896, Vol. 29, nr 2, s. 25-28Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Fulltekst (pdf)
    fulltext
  • 2. Barker, Abigail
    et al.
    Baker, Joel
    Peate, David
    Interaction of the rifting East Greenland margin with a zoned ancestral Iceland plume.2006Inngår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 34, nr 6, s. 481-484Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neodymium and high-precision lead isotopic data are presented for Paleogene East Greenland flood basalts that erupted during an early phase of magmatic activity associated with the Iceland hotspot. The 6-km-thick volcanic sequence shows marked chemostratigraphic variations: lavas in the lower half of the sequence (Milne Land and Geikie Plateau Formations) have low 206Pb/204Pb values (17.8–18.4), abruptly changing to high 206Pb/ 204Pb values (18.8–19.3) in the overlying Rømer Fjord Formation, followed by intermediate 206Pb/204Pb values (18.6–18.8) in the uppermost Skrænterne Formation. These three isotopic groups of crustally uncontaminated lavas are broadly similar to spatially distinct isotopic domains found in present-day Iceland. The East Greenland data indicate that the same mantle domains present beneath Iceland today were present in the ancestral Iceland hotspot at 55 Ma, and were sequentially tapped during continental break-up as the spatially zoned mantle interacted with the rifting continental margin. The compositional domains within the Iceland hotspot appear to be long-lived features that, given estimates of Icelandic mantle-upwelling velocities, have vertical length-scales of at least ∼500 km.

  • 3.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Coogan, L. A.
    Gillis, K. M.
    Hayman, N. W.
    Weis, D.
    Direct observation of a fossil high-temperature, fault-hosted, hydrothermal upflow zone in crust formed at the East Pacific Rise2010Inngår i: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 38, nr 4, s. 379-382Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fault zones in the ocean crust are commonly hypothesized to act as high-permeability conduits that focus fluid flow in oceanic hydrothermal systems. However, there has been little direct study of faults in crust formed at fast-spreading ridges. Here we describe the geology and geochemistry of an ∼40-m-wide fault zone within the uppermost sheeted dike complex exposed at Pito Deep (northeastern Easter microplate). Titanium in quartz thermometry gives temperatures of 392 ± 33 °C for quartz precipitation, indicating that this fault zone focused upwelling fluids at temperatures similar to those of black-smoker vent fluids. Correlated enrichment in 87Sr/86Sr and MgO in fault breccias, along with 87Sr/86Sr ratios higher than in average vent fluids, provide evidence for mixing between high-temperature upwelling fluids and a seawater-like fluid within the fault zone. Large high-temperature fluid fluxes are required to maintain high temperatures during mixing. If this fault zone is representative of upflow zones beneath hydrothermal vents on the East Pacific Rise, then it is possible that vent fluids evolve thermally and chemically during their ascent and may not record the precise conditions at the base of the hydrothermal system.

  • 4.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Coogan, L.A.
    Gillis, K.M., K.M.
    Insights into the behaviour of sulphur in mid-ocean ridge axial hydrothermal systems from the composition of the sheeted dyke complex at Pito Deep2010Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 275, nr 1-2, s. 105-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behaviour of seawater sulphate in hydrothermal systems at intermediate- to fast-spreading ridges is investigated using new analyses of the δ34S, sulphur concentration and Fe2O3/Fe2O3total, combined with existing 87Sr/86Sr, of sheeted dykes from the Pito Deep tectonic window. The Pito Deep sheeted dyke complex has a similar composition to the sheeted dykes drilled at ODP Hole 504B suggesting that the measured compositions are representative of sheeted dyke complexes at intermediate- to fast-spreading ridges. The dykes show only small increases in δ34S which, combined with the rock dominated δ34S of vent fluids, requires the majority of seawater sulphate to be precipitated as anhydrite before the fluid reacts with the sheeted dyke complex. This loss of sulphate from the fluid means that a much higher Fe2O3 in the sheeted dyke complex than in fresh MORB glasses cannot be explained by oxidation due to seawater sulphate reduction during fluid-rock reaction. Instead, oxidation probably occurs due to degassing of reduced species, largely H2, during dyke emplacement and solidification. A mass balance model that accounts for anhydrite precipitation and Sr partitioning into the anhydrite, as well as fitting the concentration and isotopic ratios of S and Sr in the sheeted dykes and vent fluids, suggests water/rock ratios of -1. For a 1km thick sheeted dyke complex this is equivalent to a fluid flux of ~3×106kgm-2, sufficient to remove ~60% of the latent heat of crystallization from the lower crust.

  • 5. Barker, Abigail
    et al.
    Coogan, L.A.
    Gillis, K.M.
    Weis, D
    Strontium isotopic constraints on fluid flow in the sheeted dyke complex of fast spreading crust: Pervasive fluid flow at Pito Deep.2008Inngår i: Geochemistry Geophysics Geosystems, E-ISSN 1525-2027, Vol. 9, nr 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fluid flow through the axial hydrothermal system at fast spreading ridges is investigated using the Sr-isotopic composition of upper crustal samples recovered from a tectonic window at Pito Deep (NE Easter microplate). Samples from the sheeted dike complex collected away from macroscopic evidence of channelized fluid flow, such as faults and centimeter-scale hydrothermal veins, show a range of 87Sr/86Sr from 0.7025 to 0.7030 averaging 0.70276 relative to a protolith with 87Sr/86Sr of ∼0.7024. There is no systematic variation in 87Sr/86Sr with depth in the sheeted dike complex. Comparison of these new data with the two other localities that similar data sets exist for (ODP Hole 504B and the Hess Deep tectonic window) reveals that the extent of Sr-isotope exchange is similar in all of these locations. Models that assume that fluid-rock reaction occurs during one-dimensional (recharge) flow lead to significant decreases in the predicted extent of isotopic modification of the rock with depth in the crust. These model results show systematic misfits when compared with the data that can only be avoided if the fluid flow is assumed to be focused in isolated channels with very slow fluid-rock exchange. In this scenario the fluid at the base of the crust is little modified in 87Sr/86Sr from seawater and thus unlike vent fluids. Additionally, this model predicts that some rocks should show no change from the fresh-rock 87Sr/86Sr, but this is not observed. Alternatively, models in which fluid-rock reaction occurs during upflow (discharge) as well as downflow, or in which fluids are recirculated within the hydrothermal system, can reproduce the observed lack of variation in 87Sr/86Sr with depth in the crust. Minimum time-integrated fluid fluxes, calculated from mass balance, are between 1.5 and 2.6 × 106 kg m−2 for all areas studied to date. However, new evidence from both the rocks and a compilation of vent fluid compositions demonstrates that some Sr is leached from the crust. Because this leaching lowers the fluid 87Sr/86Sr without changing the rock 87Sr/86Sr, these mass balance models must underestimate the time-integrated fluid flux. Additionally, these values do not account for fluid flow that is channelized within the crust.

  • 6.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Ctr Nat Hazards & Disaster Sci CNDS, Villavagen 16, SE-75236 Uppsala, Sweden.
    Hansteen, Thor H.
    GEOMAR Helmholtz Ctr Ocean Res Kiel, Wischhofstr 1-3, D-24148 Kiel, Germany.
    Nilsson, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Unravelling the Crustal Architecture of Cape Verde from the Seamount Xenolith Record2019Inngår i: Minerals, E-ISSN 2075-163X, Vol. 9, nr 2, artikkel-id 90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cape Verde oceanic plateau hosts 10 islands and 11 seamounts and provides an extensive suite of alkaline lavas and pyroclastic rocks. The volcanic rocks host a range of crustal and mantle xenoliths. These xenoliths provide a spectrum of lithologies available to interact with magma during transport through the lithospheric mantle and crust. We explore the origin and depth of formation of crustal xenoliths to develop a framework of magma-crust interaction and a model for the crustal architecture beneath the Cape Verde oceanic plateau. The host lavas are phononephelinites to phonolites and the crustal xenoliths are mostly mafic plutonic assemblages with one sedimentary xenolith. REE profiles of clinopyroxene in the host lavas are light rare-earth element (LREE) enriched whereas clinopyoxene from the plutonic xenoliths are LREE depleted. Modelling of REE melt compositions indicates the plutonic xenoliths are derived from mid-ocean ridge basalt (MORB)-type ocean crust. Thermobarometry indicates that clinopyroxene in the host lavas formed at depths of 17 to 46 km, whereas those in the xenoliths formed at 5 to 20 km. This places the depth of origin of the plutonic xenoliths in the oceanic crust. Therefore, the xenoliths trace magma-crust interaction to the MORB oceanic crust and overlying sediments located beneath the Cape Verde oceanic plateau.

    Fulltekst (pdf)
    FULLTEXT01
  • 7.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Holm, Paul M.
    Peate, David W.
    Baker, Joel A.
    A 5 million year record of compositional variations in mantle sources to magmatism on Santiago, southern Cape Verde archipelago2010Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 160, nr 1, s. 133-154Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-precision Pb isotope data and Sr–Nd–Hf isotope data are presented together with major and trace element data for samples spanning the 4.6 Ma history of volcanism at Santiago, in the southern Cape Verde islands. Pb isotope data confirm the positive Δ8/4 signature of the southern islands indicating that the north–south compositional heterogeneity in the Cape Verde archipelago has persisted for at least 4.6 Ma. The Santiago volcanics show distinct compositional differences between the old, intermediate and young volcanics, and suggest greater involvement of an enriched mantle (EM1)-like source over time. Isotopic variations in the Santiago volcanics indicate convergence towards a homogeneous EM1-like end-member and distinct temporal variations in the FOZO-like end-member. Santiago and Santo Antão (a northern island, Holm et al. 2006), show a simultaneous decrease in 208Pb/204Pb of the high 206Pb/204Pb FOZO-like source with time. Such systematic archipelago-wide variations in the FOZO-like component suggest that this component is more likely to be present as a coherent package of recycled ocean crust rather than as multiple small heterogeneities dispersed in the upwelling mantle. The temporal variations in 208Pb/204Pb reflect minor lateral variations in Th/U of this recycled ocean crust package entering the melting zone beneath the islands. The location of the EM1-like component is more equivocal. A shallow lithospheric location is possible, but this would require a coincidence between spatial compositional variations in the lithosphere (EM1 is spatially restricted to the southern islands) and flow lines in the upwelling mantle revealed by seismic anisotropy. Therefore, we favour a deeper asthenospheric mantle source for the EM1-like source.

  • 8.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Holm, Paul M.
    Peate, David W.
    Baker, Joel A.
    Geochemical Stratigraphy of Submarine Lavas (3–5 Ma) from the Flamengos Valley, Santiago, Southern Cape Verde Islands2009Inngår i: Journal of Petrology, ISSN 0022-3530, E-ISSN 1460-2415, Vol. 50, nr 1, s. 169-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New high-precision Pb–Sr–Nd isotope, major and traceelement and mineral chemistry data are presented for the submarinestage of ocean island volcanism on Santiago, one of the southernislands of the Cape Verde archipelago. Pillow basalts and hyaloclastitesin the Flamengos Valley are divided into three petrographicand compositional groups; the Flamengos Formation lavas (4·6Ma) dominate the sequence, with the younger Low Si and Coastalgroups (2·8 Ma) found near the shoreline. Olivine andclinopyroxene compositions and isotopic data for minerals andtheir host melts indicate disequilibrium between some crystalsand the melt. Intra-sample disequilibrium suggests homogenisationof liquids but eruption before complete equilibration betweencrystals and melt preserves the heterogeneity. Pressures ofcrystallization for clinopyroxene (0·4–1·1GPa) indicate stalling and crystallization of the magmas overa range of depths in the lithosphere. Major element compositionsindicate melting of a carbonated eclogite source. Sr–Nd–Pbisotope data suggest the involvement of FOZO-like and EM1-likecomponents in the mantle source, which are simultaneously availableat all depths in the melting column. The Flamengos Valley lavasdisplay large compositional variations, often between stratigraphicallyadjacent flows; these frequent abrupt changes of magma compositionsuggest stalling and crystallization of discrete magma batcheson transport through the lithosphere.

  • 9.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Holm, Paul Martin
    Unniversity of Copenhagen.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    The role of eclogite in the mantle heterogeneity at Cape Verde2014Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 168, nr 3, s. 1052-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 10.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jakabová, Vanda
    Nilsson, Emma
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Andersson Sundén, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Gustavsson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Lantz, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Paatero, Jussi
    Salminen-Paatero, Susanna
    The impact of climate change on radiocesium mobility2024Rapport (Annet vitenskapelig)
    Abstract [en]

    We investigate variations in 137Cs activities, temperature and rainfall with time and predict how climate change will interact with existing 137Cs anomalies. We focus on several case-studies affected by distal fallout from Chernobyl; the Kymijoki watershed in Finland, Gävle in Sweden and Bavaria in Southeast Germany. In addition, we investigate 137Cs activities in Japan as a contrasting location proximal to the Fukushima nuclear power plant that was damaged during the tsunami in 2011. In Europe we find that 137Cs anomalies show up in moose, mushrooms and ground radiation levels in specific years that differ from place to place. There is little indication of direct relationships between weather conditions and 137Cs anomalies. However, environmental processes play critical roles in radionuclide behavior and may themselves be influenced by weather conditions and furthermore by changing climate. Erosion likely remobilizes subsurface 137Cs and transports it downstream where it may be deposited. Erosion is driven by heavy rainfall, snowmelt, and daily variations in temperature that alternatively freeze and thaw the ground. These insights have helped us interpret signs of erosion and deposition of soil contaminated with 137Cs in our case-study areas. Future variations in temperature, precipitation and extreme weather events will likely increase the occurrence of erosion and hence the redistribution of 137Cs in the environment. We have identified several areas sensitive to accumulation of and hence contamination by 137Cs in Europe. In most places the levels of 137Cs accumulation are rarely hazardous, however we recommend that local authorities assess the risks of new construction sites, agricultural practices and free-time activities such as hunting game and gathering mushrooms in areas that are sensitive to 137Cs accumulation.

    Fulltekst (pdf)
    fulltext
  • 11.
    Barker, Abigail K.
    et al.
    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.
    Ellam, R.M.
    Hansteen, T.H.
    Haris, C.
    Stillman, C.J.
    Andersson, A.
    Magmatic evolution of the Cadamosto Seamount, Cape Verde: Beyond the spatial extent of EM12012Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 163, nr 6, s. 949-965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 12.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden.
    Magnusson, E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling. Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden;Instituto de Estudios Ambientales y Recursos Naturales (iUNAT), Universidad de Las Palmas de Gran Canaria (ULPGC), Las Palmas de Gran Canaria 35017, Spain.
    Harris, C.
    Mattsson, Hannes B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Institute for Mineralogy and Petrology, ETH Zürich, Switzerland.
    Holm, P.M.
    Perez-Torrado, F.J.
    Carracedo, J.C.
    Deegan, Frances
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling. Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden.
    Disequilibrium in historic volcanic rocks from Fogo, Cape Verde traces carbonatite metasomatism of recycled ocean crust2023Inngår i: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, s. 107328-107328, artikkel-id 107328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fogo, Cape Verde, located upon thick oceanic lithosphere, provides a window into processes occurring in the mantle where recycled ocean crust in an upwelling mantle plume interacts with ambient mantle. Our objective is to investigate the nature of the lithologies of the mantle sources involved in the petrogenesis of historic volcanic rocks from Fogo. We observe enclaves and mingling textures in the lavas combined with oxygen isotope disequilibrium between olivine and clinopyroxene phenocrysts. Olivine δ18O values display positive correlations with Zr/Hf and Zr/Y and a negative correlation with U/Th, whereas clinopyroxene δ 18O values correlate positively with Ba/Nb. Heterogeneity between crystal populations and within the groundmass indicates that multiple magma batches are mixed beneath Fogo. In terms of mantle endmembers and source lithologies, a HIMU endmember was generated by melting of carbonated eclogite as indicated by low δ 18O values, Zr/Hf, Ba/Nb and high U/Th ratios. In contrast, we show the EM1 endmember has high δ 18O, Zr/Hf, Ba/Nb and low U/Th ratios, derived from melting of variably carbonated peridotite. Additionally, Ba/Th ratio are high, indicating that carbonatite melts have contributed to alkaline magma compositions at Fogo.

    Fulltekst (pdf)
    fulltext
  • 13.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre of Natural Hazards and Disaster Sciences, Uppsala, Sweden.
    Rydeblad, Elin M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Imperial College London.
    Silva, Sónia M. D. M.
    University of Cape Verde.
    Magma storage at Ocean Islands: insights from Cape Verde2021Inngår i: Crustal Magmatic System Evolution: Anatomy, Architecture and Physico-Chemical Processes / [ed] Matteo Masotta, Christoph Beier & Silvio Mollo, American Geophysical Union (AGU), 2021, s. 45-78Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The Cape Verde archipelago is a group of ocean islands in the Central Atlantic that forms two chains of islands trending northwest and southwest. Several of the islands are considered to be volcanically active, with frequent eruptions on Fogo. We examine the mineral chemistry and thermobarometry of the southern islands—Santiago, Fogo, and Brava—together with the Cadamosto Seamount. Our objective is to explore the magmatic storage system and implications for volcanic eruptions and associated hazards at Cape Verde. The volcanic rocks at Cape Verde are alkaline and dominantly mafic, whereas the island of Brava and the Cadamosto Seamount are unusually felsic. Clinopyroxene compositions range from 60 to 90 Mg# at Santiago and Fogo. In contrast, at Brava and the Cadamosto Seamount, the clinopyroxene compositions are 5 to 75 Mg#. Mineral chemistry and zonation records fractional crystallization, recharge, aggregation of crystals, magma mixing, and variations in thermal conditions of the magma at temperatures from 925 to 1250 °C. Magma storage depths at Santiago, Fogo, Brava, and the Cadamosto Seamount are between 12 and 40 km, forming deep sub-Moho magma storage zones. Transient magma storage in the crust is suggested by fluid inclusion re-equilibration and pre-eruption seismicity. A global compilation of magma storage at ocean islands suggests that deep magma storage is a common feature, and volcanic eruptions are often associated with rapid magma ascent through the crust. Shallow magma storage is more variable and likely reflects local variations in crustal structure, sediment supply, and tectonics. Petrological constraints on the magma plumbing system at Cape Verde and elsewhere are vital to integrate with deformation models and seismicity in order to improve understanding and mitigation of the volcanic hazards.

  • 14.
    Barker, Abigail
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Las Palmas, GEOVOL, La Palmas Gran Canaria 35017, Spain.
    Carracedo, Juan Carlos
    Univ Las Palmas, GEOVOL, La Palmas Gran Canaria 35017, Spain.
    Nicholls, Peter A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    The magma plumbing system for the 1971 Teneguía eruption on La Palma, Canary Islands2015Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 170, nr 5-6, artikkel-id 54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

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

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

  • 15.
    Berg, S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Troll, V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Freda, C.
    Mancini, L.
    Masotta, M.
    Brun, F.
    Blythe, L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Jolis, E. M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Annersten, H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Barker, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Experimental simulation of crustal volatile release in magmatic conduits2012Konferansepaper (Annet vitenskapelig)
  • 16. Busby, CJ
    et al.
    Tamura, Y
    Blum, P
    Guerin, G
    Andrews, GDM
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Berger, Julien LR
    Bongiolo, EM
    Bordiga, Manuela
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi.
    DeBari, SM
    Gill, JB
    Hamelin, C
    Jia, Jihui
    John, EH
    Jonas, Ann-Sophie
    Jutzeler, Martin
    Kars, Myriam AC
    Kita, Zachary A
    Konrad, Kevin
    Mahony, Susan H
    Martini, Michelangelo
    Miyazaki, Takashi
    Musgrave, Robert J
    Nascimento, Debara B
    Nichols, Alexander R L
    Ribeiro, Julia M
    Sato, Tomoki
    Schindlbeck, Julie C
    Schmitt, Axel K
    Straub, Susanne M
    Mleneck-Vautravers, Maryline J
    Yang, Alexandra Yang
    The missing half of the subduction factory: shipboard results from the Izu rear arc, IODP expedition 3502017Inngår i: International Geology Review, ISSN 0020-6814, E-ISSN 1938-2839, Vol. 59, nr 13, s. 1677-1708Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

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

  • 17.
    Callegari, Riccardo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Krakow, Fac Geol Geophys & Environm Protect, Krakow, Poland..
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barnes, Christopher J.
    Polish Acad Sci, Inst Geol Sci, Krakow, Poland..
    Walczak, Katarzyna
    AGH Univ Krakow, Fac Geol Geophys & Environm Protect, Krakow, Poland..
    Ziemniak, Grzegorz
    Univ Wroclaw, Inst Geol Sci, Wroclaw, Poland..
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Kooijman, Ellen
    Swedish Museum Nat Hist, Dept Geosci, Stockholm, Sweden..
    Rousku, Sabine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Växtekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Kosminska, Karolina
    AGH Univ Krakow, Fac Geol Geophys & Environm Protect, Krakow, Poland..
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Krakow, Fac Geol Geophys & Environm Protect, Krakow, Poland..
    A depleted mantle source for Neoproterozoic continental rifting in the Seve Nappe Complex, Kebnekaise region, northern Swedish Caledonides2024Inngår i: Frontiers in Earth Science, E-ISSN 2296-6463, Vol. 12, artikkel-id 1426525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Central Iapetus Magmatic Province (CIMP) is a large igneous province (LIP) emplaced in the Baltican and Laurentian paleocontinents that marks the onset of the Caledonian Wilson Cycle. Paleozoic magmatism of the CIMP is preserved in both northeastern America and northern Europe. This study investigates rocks belonging to the hyper-extended margin of Baltica currently found in the Seve Nappe Complex of the Scandinavian Caledonides. Specifically, U-Pb zircon geochronology and whole-rock geochemistry are applied to a migmatitic variety of the Vierru & ccaron;ohkka amphibolite of the M & aring;rma Terrane, to the Aurek gabbro, and amphibolite of the Aurek Assemblage exposed in the Seve Nappe Complex in the Kebnekaise region, northern Swedish Caledonides. U-Pb zircon geochronology yields crystallization ages of 626 +/- 7 Ma for the protolith of the Vierru & ccaron;ohkka amphibolite, and 614 +/- 2 Ma and 609 +/- 1 Ma for the emplacement of the Aurek gabbro and amphibolite protolith, respectively. A younger age of 599 +/- 3 Ma is recorded in the Vierru & ccaron;ohkka amphibolite and is interpreted as the age of partial melting and migmatization. The geochemical signatures of the rocks demonstrate crustal assimilation during the emplacement of their protoliths and modification due to prograde metamorphic processes during Caledonian subduction. The Vierru & ccaron;ohkka amphibolite and the Aurek Assemblage samples display upper and lower crustal assimilation, respectively. Trace elements (Dy, Sm, Lu, and Y) record the growth of metamorphic garnet, while elevated TiO2 contents record the crystallization of metamorphic rutile. Nevertheless, high field strength elements (HSFE) and triangle Nb suggest a depleted mantle source for the magmas of the protoliths of the investigated rocks. Altogether, geochemical data indicate that the igneous activity recorded in the Vierru & ccaron;ohkka amphibolite and the Aurek Assemblage between c. 626-609 Ma is related to continental rifting processes associated with the opening of the Iapetus Ocean.

    Fulltekst (pdf)
    fulltext
  • 18.
    Callegari, Riccardo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Kośmińska, Karolina
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Barnes, Christopher J.
    Institute of Geological Sciences, Polish Academy of Sciences, Kraków, Poland.
    Klonowska, Iwona
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Barker, Abigail K.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Rousku, Sabine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Nääs, Erika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Kooijman, Ellen
    Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Witt-Nilsson, Patrik
    Rosmarus Enviro, Uppsala, Sweden.
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Early Neoproterozoic magmatism and Caledonian metamorphism recorded by the Mårma terrane, Seve Nappe Complex, northern Swedish Caledonides2023Inngår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 180, nr 5, artikkel-id jgs2022-092Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Petrology, geochronology and bulk-rock chemistry are combined to investigate the early Neoproterozoic magmatism and Cambrian–Ordovician metamorphism in the northern Swedish Caledonides. This work includes several lithologies of the Mårma terrane in the Seve Nappe Complex exposed in the Kebnekaise region. U–Pb zircon geochronology yielded crystallization ages of 835 ± 8 Ma for a mylonitic orthogneiss, 864 ± 3 Ma for the Vistas Granite and 840 ± 7 Ma for an intruded granitic dyke, whereas a gabbro and a granodiorite intrusion gave U–Pb zircon crystallization ages of 856 ± 3 Ma and 850 ± 1 Ma, respectively. U–Pb monazite dating of the mylonitic orthogneiss gave an upper intercept age of 841 ± 7 Ma and a lower intercept age of 443 ± 20 Ma. Pressure–temperature estimates derived for the mylonitic orthogneiss reveal metamorphic peak-pressure and peak-temperature of 10.5–11.75 kbar and 550–610°C and 7.4–8.1 kbar at 615–675°C, respectively. Metamorphic pressure–temperature estimates for the Vistas Granite yield 6.5–7.5 kbar at 600–625°C. Whole-rock chemistry coupled with U–Pb geochronology indicates that bimodal magmatism was related to attempted rifting of Rodinia between 870 and 840 Ma.

  • 19.
    Callegari, Riccardo
    et al.
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland;Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Kośmińska, Karolina
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland.
    Barnes, Christopher J.
    Institute of Geological Sciences, Polish Academy of Sciences, Kraków, Poland.
    Klonowska, Iwona
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland;Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Barker, Abigail K.
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Rousku, Sabine
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Nääs, Erika
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Kooijman, Ellen
    Naturhistoriska riksmuseet, Enheten för geovetenskap. Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden.
    Witt-Nilsson, Patrik
    Rosmarus Enviro, Uppsala, Sweden.
    Majka, Jarosław
    Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Kraków, Poland;Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Early Neoproterozoic magmatism and Caledonian metamorphism recorded by the Mårma terrane, Seve Nappe Complex, northern Swedish Caledonides2023Inngår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 180, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Petrology, geochronology and bulk-rock chemistry are combined to investigate the early Neoproterozoic magmatismand Cambrian–Ordovician metamorphism in the northern Swedish Caledonides. This work includes several lithologies of theMårma terrane in the Seve Nappe Complex exposed in the Kebnekaise region. U–Pb zircon geochronology yielded crystallizationages of 835 ± 8 Ma for a mylonitic orthogneiss, 864 ± 3 Ma for the Vistas Granite and 840 ± 7 Ma for an intruded granitic dyke,whereas a gabbro and a granodiorite intrusion gave U–Pb zircon crystallization ages of 856 ± 3 Ma and 850 ± 1 Ma, respectively.U–Pb monazite dating of the mylonitic orthogneiss gave an upper intercept age of 841 ± 7 Ma and a lower intercept age of443 ± 20 Ma. Pressure–temperature estimates derived for the mylonitic orthogneiss reveal metamorphic peak-pressure and peaktemperatureof 10.5–11.75 kbar and 550–610°C and 7.4–8.1 kbar at 615–675°C, respectively.Metamorphic pressure–temperatureestimates for the Vistas Granite yield 6.5–7.5 kbar at 600–625°C. Whole-rock chemistry coupled with U–Pb geochronologyindicates that bimodal magmatism was related to attempted rifting of Rodinia between 870 and 840 Ma.

  • 20.
    Carracedo, Juan-Carlos
    et al.
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Perez-Torrado, Francisco J.
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Rodriguez-Gonzalez, Alejandro
    University of Las Palmas de Gran Canaria, Dept. of Physics, Las Palmas de Gran Canaria, Spain.
    Paris, Raphael
    Université Blaise Pascal Clermont-Ferrand II, France.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Volcanic and structural evolution of Pico do Fogo, Cape Verde2015Inngår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, nr 4, s. 146-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 21.
    Dahrén, Börje
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Meade, Fiona C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Freda, C.
    Istituto Nazionale de Geofisica e Vulcanologia, Rome, Italy.
    Holm, Paul Martin
    University of Copenhagen, Department of Geosciences and Natural Resource Management, Øster Voldgade 10, Copenhagen DK-1350, Denmark.
    Søager, Nina
    GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany.
    Plagioclase mineral chemistry in the Faroe Islands Basalt Group2016Inngår i: Annales societatis scientiarum Færoensis. Supplementum, ISSN 0365-6772, Vol. 64, s. 45-56Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Day, James M. D.
    et al.
    Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA..
    Pearson, D. Graham
    Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3, Canada..
    Kjarsgaard, Bruce A.
    Geol Survey Canada, 601 Booth St, Ottawa, ON K1A 0E8, Canada..
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Nowell, Geoff M.
    Univ Durham, Dept Earth Sci, Durham DH1 3LE, England..
    Joyce, Nancy
    Geol Survey Canada, 601 Booth St, Ottawa, ON K1A 0E8, Canada..
    Lowry, David
    Royal Holloway Univ London, Dept Earth Sci, Egham TW20 0EX, England..
    Sarkar, Chiranjeeb
    Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3, Canada..
    Harrison, Christopher
    Geol Survey Canada, 3303-33 St NW, Calgary, AB T2L 2A7, Canada..
    Early Eocene Arctic volcanism from carbonate-metasomatized mantle2023Inngår i: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 178, nr 12, artikkel-id 91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Melilitite, nephelinite, basanite, and alkali basalt, along with phonolite differentiates, form the Freemans Cove Complex (FCC) in the south-eastern extremity of Bathurst Island (Nunavut, Canada). New Ar-40/Ar-39 chronology indicates their emplacement between similar to 56 and similar to 54 million years ago within a localized extensional structure. Melilitites and nephelinites, along with phonolite differentiates, likely relate to the beginning and end phases of extension, whereas alkali basalts were emplaced during a main extensional episode at similar to 55 Ma. The melilitites, nephelinites, and alkali basalts show no strong evidence for significant assimilation of crust, in contrast to some phonolites. Partial melting occurred within both the garnet- and spinel-facies mantle and sampled sources with He, O, Nd, Hf, and Os isotope characteristics indicative of peridotite with two distinct components. The first, expressed in higher degree partial melts, represents a relatively depleted component ("A"; He-3/He-4 similar to 8 R-A, epsilon(i)(Nd) similar to + 3 epsilon(Hf)i similar to + 7, gamma(Os)i similar to 0). The second was an enriched component ("B" He-3/He-4 < 3 R-A, epsilon(Nd)i < - 1 epsilon(Hf)i < + 3, gamma(Os)i > + 70) sampled by the lowest degree partial melts and represents carbonate-metasomatized peridotite. Magmatism in the FCC shows that rifting extended from the Labrador Sea to Bathurst Island and reached a zenith at similar to 55 Ma, during the Eurekan orogeny. The incompatible trace-element abundances and isotopic signatures of FCC rocks indicate melt generation occurred at the base of relatively thin lithosphere at the margin of a thick craton, with no mantle plume influence. FCC melt compositions are distinct from other continental rift magmatic provinces worldwide, and their metasomatized mantle source was plausibly formed synchronously with emplacement of Cretaceous kimberlites. The FCC illustrates that the range of isotopic compositions preserved in continental rift magmas are likely to be dominated by temporal changes in the extent of partial melting, as well as by the timing and degree of metasomatism recorded in the underlying continental lithosphere.

    Fulltekst (pdf)
    FULLTEXT01
  • 23.
    Deegan, Frances M.
    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.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Harris, C.
    Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa.
    Chadwick, J.P.
    Science Gallery, Trinity College Dublin, Dublin 2, Ireland.
    Carracedo, J.C.
    Departamento de Física (GEOVOL), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.
    Delcamp, A.
    Department of Geography, Vrije Universiteit Brussels, Belgium.
    Crustal versus source processes recorded in dykes from the Northeast volcanic rift zone of Tenerife, Canary Islands2012Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 334, s. 324-344Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Miocene–Pliocene Northeast Rift Zone (NERZ) on Tenerife is a well exposed example of a feeder system to a major ocean island volcanic rift. We present elemental and O–Sr–Nd–Pb isotope data for dykes of the NERZ with the aim of unravelling the petrological evolution of the rift and ultimately defining the mantle source contributions. Fractional crystallisation is found to be the principal control on major and trace element variability in the dykes. Differing degrees of low temperature alteration and assimilation of hydrothermally altered island edifice and pre-island siliciclastic sediment elevated the δ18O and the 87Sr/86Sr ratio of many of the dykes, but had little to no discernible effect on Nd and Pb isotopes. Once the data are screened for alteration and shallow level contamination, the underlying source variations of the NERZ essentially reflect derivation from a young High-μ (HIMU, where μ = 238U/204Pb)-type mantle component mixed with depleted mid-ocean ridge-type mantle (DMM). The Pb isotope data of the NERZ rocks (206Pb/204Pb and 207Pb/204Pb range from 19.591 to 19.838 and 15.603 to 15.635, respectively) support a model of initiation and growth of the rift from the Central Shield volcano (Roque del Conde), consistent with latest geochronology results. The similar isotope signature of the NERZ to both the Miocene Central Shield and the Pliocene Las Cañadas central volcano suggests that the central part of Tenerife Island was supplied from a mantle source that remained of similar composition through the Miocene to the Pliocene. This can be explained by the presence of a discrete column of young HIMU-like plume material, ≤ 100 km in vertical extent, occupying the melting zone beneath central Tenerife throughout this period. The most recent central magmatism on Tenerife appears to reflect greater entrainment of DMM material, perhaps due to waning of the HIMU-like “blob” with time.

  • 24.
    Duan, Haochen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jeon, Heejin
    Swedish Museum of Natural History.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Formation of enriched mantle by serpentinite-dominated mélange beneath the Izu rear-arcManuskript (preprint) (Annet vitenskapelig)
  • 25.
    Duan, Haochen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jeon, Heejin
    Swedish Museum of Natural History.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Zhang, Chao
    Northwest University.
    Boron isotope fractionation during partial melting of oceanic rear-arc crustManuskript (preprint) (Annet vitenskapelig)
  • 26.
    Duan, Haochen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jeon, Heejin
    Swedish Museum of Natural History.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Zhang, Chao
    Northwest University.
    Continental crust genesis at intra-oceanic arcs insights from the Izu rear-arc.Manuskript (preprint) (Annet vitenskapelig)
  • 27.
    Duan, Haochen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jeon, Heejin
    Swedish Museum of Natural History.
    Zhang, Chao
    Northwest University.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Basaltic and andesitic melt inclusions record crustal assimilation in the Izu rear-arcManuskript (preprint) (Annet vitenskapelig)
  • 28.
    Duan, Haochen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Jeon, Heejin
    Swedish Museum of Natural History.
    Zhang, Chao
    Northwest University.
    Whitehouse, Martin
    Swedish Museum of Natural History.
    Generation of diverse rhyolitic magmas in the Izu rear-arc and association with continental crustManuskript (preprint) (Annet vitenskapelig)
  • 29.
    Geiger, Harri
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail K.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Univ Las Palmas Gran Canaria, Dept Phys GEOVOL, La Palmas Gran Canaria, Spain.
    Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon2016Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 6, artikkel-id 33629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano’s underlying magma supply system is sparse. To characterize Mt. Cameroon’s magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano’s two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs.

    Fulltekst (pdf)
    fulltext
  • 30.
    Goluchowska, Karolina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Czerny, Jerzy
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Manecki, Maciej
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Farajewicz, Milena
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Dwornik, Maciej
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.
    Magma storage of an alkali ultramafic igneous suite from Chamberlindalen, SW Svalbard2016Inngår i: Mineralogy and Petrology, ISSN 0930-0708, E-ISSN 1438-1168, Vol. 110, nr 5, s. 623-638Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An alkali mafic-ultramafic igneous suite of composite intrusions, lenses and associated greenstones are hosted by Neoproterozoic metasedimentary sequences in Chamberlindalen, Southwest Svalbard. This study focuses on the alkali igneous suite of Chamberlindalen with a view to determining the conditions of magma storage. The rocks from Chamberlindalen display cumulate textures, are highly magnesian and are classified as alkaline by the occurrence of kaersutite. They have textures that indicate cocrystallization of primary magmatic minerals such as diopside, kaersutite-ferrokaersutite and biotite-phlogopite in different proportions. The historic magma plumbing system for the alkaline cumulates has been reconstructed by thermobarometry. Diopside and kaersutite crystallization in the alkaline cumulates show a dominant level of magma storage between 30 and 50 km in the subcontinental lithospheric mantle.

  • 31.
    Goluchowska, Karolina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Manecki, Maciej
    Cyernz, Jeryz
    Bayarnik, Jakub
    Preservation of magmatic signals in metavolcanics from Wedel Jarlsberg Land, SW Svalbard2012Inngår i: Mineralogia, ISSN 1899-8291, E-ISSN 1899-8526, Vol. 43, s. 179-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study is to determine the role of metamorphism and thereby identify the preserved magmatic signature in metavolcanics from Wedel Jarlsberg Land in southwestern Svalbard. Samples have been collected from late Precambrian metavolcanics occurring within metasedimentary rocks of the Sofiebogen Group, as well as dikes cutting older metasedimentary rocks of the Deilegga Group. The volcanic rocks were metamorphosed under greenschist facies conditions during the Caledonian Orogeny. To investigate the role of metamorphism, we present petrography, major and trace element geochemistry, and use factor analysis as a tool to identify correlations that correspond to primary magmatic signals.

    The metavolcanics are classified as subalkaline basalt to basaltic andesite and they contain relicts of primary clinopyroxene and plagioclase. The metamorphic minerals are actinolite, secondary plagioclase, chlorite and minerals belonging to the epidote group. Major element variations are highly scattered with no obvious trends observed. The HFSE and REE show strong trends attributed to fractional crystallization. The LILE, Th and La show elevated contents in some samples.

    Factor analysis shows that the HFSE and REE are well correlated. The LILE form a separate well correlated group, while the major elements are not correlated, except for Na2O, Fe2O3 and CaO. The lack of correlation for major elements, as well as the lack of observed fractional crystallization trends between these elements suggests that they were modified by metamorphism. The strong correlation of HFSE and REE reflects the original geochemical signal generated by magmatic processes. The correlation of the LILE is consistent with their elevated composition implying the influence of crustal contamination processes, and though some variability is likely superimposed due to metamorphism, the primary magmatic record is not completely destroyed. We conclude that the HFSE and REE are not influenced by metamorphic processes and therefore provide robust records of magmatic processes.

  • 32.
    Goluchowska, Karolina
    et al.
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.;Uppsala Univ, Dept Earth Sci, Mineral Petrol Tecton, Villavagen 16, SE-75236 Uppsala, Sweden..
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Manecki, Maciej
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland.;Uppsala Univ, Dept Earth Sci, Mineral Petrol Tecton, Villavagen 16, SE-75236 Uppsala, Sweden..
    Kosminska, Karolina
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland..
    Ellam, Robert M.
    Scottish Univ Environm Res Ctr, East Kilbride G75 0QF, Scotland..
    Bazarnik, Jakub
    Polish Geol Inst, Natl Res Inst, Carpathian Branch, Skrzatow 1, PL-31560 Krakow, Poland..
    Faehnrich, Karol
    Dartmouth Coll, Dept Earth Sci, Hanover, NH 03755 USA..
    Czerny, Jerzy
    AGH Univ Sci & Technol, Fac Geol Geophys & Environm Protect, Al Mickiewicza 30, PL-30059 Krakow, Poland..
    Majka, Jaroslaw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    The role of crustal contamination in magma evolution of Neoproterozoic metaigneous rocks from Southwest Svalbard2022Inngår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 370, artikkel-id 106521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Late Neoproterozoic metavolcanic rocks occur along the Southwest coast of Svalbard. The protoliths of the metavolcanic rocks from Wedel Jarlsberg Land and Nordenskiold Land are mainly diabase, basalt and felsic tuff of tholeiitic affinity associated with continental magmatism. We investigate the magma evolution of the meta-volcanic rocks paying particular attention to processes of magma-crust interaction and assess potential sources of crustal contamination. These goals are achieved by employing trace element geochemistry, as well as Sr and Nd isotope geochemistry. Metavolcanic rocks from the South (Orvindalen and Werenskioldbreen) have higher LREE, LILE and Th compared to rocks from the North (Nordenskiold Land), which are relatively enriched in Sr. Incompatible element ratios like Th/La, Th/Nb, La/Nb, Th/Yb and Nb/Yb also decrease from South to North. The Nd-143/Nd-144(635 Ma) ranges from 0.511396 to 0.512356 and increases from South to North. For Sr isotopes, the metavolcanic rocks show a wide range, however in the South we observe Sr-87/Sr-86(635 Ma) of 0.70407-0.73043 and in the North Sr-87/Sr-86(635 Ma) of 0.70410-0.71028. Energy Constrained - Assimilation and Fractional Crystallization (EC-AFC) modelling indicates that the extent of magma contamination is highest in the South. Additionally the modelling suggests fractional crystallization and assimilation of granulite or amphibolite followed by shale for the metavolcanic rocks in the South and for the North mixtures of carbonate and shale contributed. This geographical pattern of assimilation reflects the upper crustal metasedimentary sequences, where phyllites are common in the South (Orvindalen and Werenskioldbreen) and carbonates are more common in the North (Nordenskiold Land). Density contrasts and impermeable layers within the continental crust would likely have acted as barriers to ascending magma, forcing it to stall and providing opportunities for magma-crust interaction.

    Fulltekst (pdf)
    fulltext
  • 33.
    Gustavsson, Cecilia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson-Sundén, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Hjalmarsson, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Lantz, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Lundén, Karl
    Pomp, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Citizen science in radiation research2020Inngår i: ND 2019: International Conference on Nuclear Data for Science and Technology, 2020, artikkel-id 25001Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A growing trend in science is that research institutions reach out to members of the public for participating in research. The reasons for outreach are many, spanning from the desire to collect and/or analyse large sets of data efficiently, to the idea of including the general public on a very fundamental level in science-making and ultimately decision-making. The presented project is curriculum-based and carried out in 240 lower secondary school classes (pupils of age 13-16). The task, as designed by the participating universities, is to collect mushrooms, soil and animal droppings from different parts of Sweden, do preliminary sample preparation and analyses and send the samples to the university institutions for radioactivity measurement. Behind the project is a desire to compare today’s levels of 137Cs with those deposited right after the Chernobyl accident in 1986, but also to study the exchange of caesium between organisms as well as the impacts of biological and geological processes on uptake and retention. The scientific outcome is a geodatabase with the 137Cs activity (Bq/m2) present in the Swedish environment, where radioactivity data can be linked to the species (fungi, competing species, animals foraging), forest type, land type, land use and other environmental factors. The science question is of interest to the general public as foraging for mushrooms, as well as spending recreational time in forests is widely popular in Sweden. In this article, we will discuss the current status of the project and the observations we have made about how well the public can participate in scientific research. Focus will be on organization of the project, such as logistics, preparation of supportive material, feedback and communication between researchers and schools. We will present observations about the impact the project has had on the participants, based on quantitative and qualitative evaluations.

    Fulltekst (pdf)
    fulltext
  • 34.
    Holm, Paul Martin
    et al.
    University of Copenhagen.
    Grandvuinet, T
    University of Copenhagen.
    Friis, J
    University of Copenhagen.
    Wilson, J.R.
    University of Aarhus.
    Barker, Abigail
    Plesner, Susanne
    An 40Ar-39Ar study of the Cape Verde hotspot: Temporal evolution in a semi-staionary plate environment.2008Inngår i: Journal of Geophysical Research: Solid Earth, ISSN 1934-8843, Vol. 113, nr B8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 40Ar-39Ar analyses of 28 groundmass separates from volcanic rocks from the islands of Santiago, Sal, and São Vicente, Cape Verde archipelago, are presented. The new age data record the volcanic evolution for Santiago from 4.6 to 0.7 Ma, for Sal from around 15 to 1.1 Ma, and for São Vicente from 6.6 to 0.3 Ma. The major submarine constructional phase of Santiago was erupted within a few hundred thousand years interval around 4.6 Ma. Most of the subaerial Santiago volcanic rocks were erupted in a second episode from 3.3 to 2.2 Ma and late volcanism occurred at 1.1-0.7 Ma. Volcanism on Sal evolved in five stages: (1) poorly constrained early Miocene activity, (2) 16-14 Ma, (3) 12-8 Ma, (4) around 5.4 Ma, and (5) 1.1-0.6 Ma. São Vicente was constructed during three active periods: (1) >6.6-5.9 Ma, (2) 4.7-4.5 Ma, and (3) ~0.3 Ma. Sr isotope analyses of carbonates from Maio confirm an Early Cretaceous age for limestones deposited on the seafloor and later uplifted. The Cape Verde Rise is indicated to have fully formed in the early Miocene around 22 Ma, accompanied by the initial alkaline volcanism. Considerable volcanism on Sal, Boa Vista, and Maio took place in the Miocene and Pliocene and extended over much larger areas than the present islands, whereas volcanism of the southwestern and northwestern island groups developed mainly during the Pliocene and Pleistocene and was mostly confined to the present island areas. The periods of volcanic activity may be broadly correlated between the northwestern and southwestern groups of islands. Young volcanism (0.3-0.1 Ma) throughout the northwestern group extends along a 150 km long NW-SE trending lineament. A relatively moderate average melting rate for the hot spot over the 22 Ma period is estimated at ~0.026 km3/a, corresponding to a total volume of 570 × 103 km3 of magma emplaced in the crust and a mantle volume flux of 28 m3/s, much lower than Iceland or Hawaii. The archipelago is situated to the south and SW of the center of the mantle plume anomaly and ahead of its relative movement. The timing and location of volcanism suggest that mantle melting takes place in three channels, an eastern one that has been active for 22 Ma and in southwestern and northwestern channels since late Miocene

  • 35.
    Lantz, Mattias
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson Sundén, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Gustavsson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Hjalmarsson, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacewicz, Marek
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, FREIA.
    Lundén, Karl
    Marciniewski, Pawel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärnfysik.
    Pomp, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Rathore, Vikram
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Ziemann, Volker
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, FREIA.
    Gamma spectroscopy methodology for large amounts of environmental samples in Sweden 30 years after the Chernobyl accident2020Inngår i: ND 2019: International Conference on Nuclear Data for Science and Technology, 2020, artikkel-id 25002Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a Swedish citizen science project, more than 200 elementary school classes participated in collecting fungi, soil samples, and droppings from deer and wild boar, from all over Sweden. The samples have been sent to a laboratory at Uppsala University where they are being analyzed through gamma spectroscopy with a shielded HPGe detector. The main objective is to scan the samples for 137Cs from the Chernobyl accident and compare the data with measurements from 1986, but uptake of naturally occuring radionuclides like 40K and radon daughters will also be determined. Together with the soil samples, transfer factors will be derived, and correlations for these factors will be sought for different species of fungi and soil types. The potential for correlating the results with different biological processes will also be investigated, in part through the collected animal droppings. This is a work in progress where the present status of the experimental setup and methodology are presented. Issues with the initial approach for corrections are discussed and preliminary results are presented.

    Fulltekst (pdf)
    fulltext
  • 36.
    Majka, Jaroslaw
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Prsek, J.
    Budzyn, B.
    Bacik, P.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Lodzinski, M.
    Fluorapatite-hingganite-(Y) coronas as products of fluid-induced xenotime-(Y) breakdown in the Skoddefjellet pegmatite, Svalbard2011Inngår i: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 75, nr 1, s. 159-167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pre-Caledonian NYF Skoddefjellet pegmatite in Wedel Jarlsberg Land, Svalbard, contains xenotime-(Y) that is partly replaced by fluorapatite-hingganite-(Y) reaction coronas. Hingganitc-(Y) contains up to 2.0 wt.% of Gd2O3, 4.7 wt.% of Dy2O3, 3.3 wt.% of Er2O3 and 5.5 wt.% of Yb2O3. Such unusual, previously undescribed, xenotime-(Y) breakdown was caused by Ca- and F-bearing fluids interacting with the pegmatite. The occurrence of hinnganite-(Y) as a breakdown product of xenotime-(Y) implies that a Be-bearing phase (beryl in this case) was also involved in the reaction. There are few Ca-bearing primary phases in the pegmatite, indicating that the source of fluid was probably located in the generally Ca-richer host rocks (metasediments), though the fluid composition was modified during metasomatism of the pegmatite (i.e. beryl dissolution).

  • 37.
    Peate, David
    et al.
    University of Iowa.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Rishuus, Morten
    University of Iceland.
    Andreasen, Rasmus
    Temporal variations in crustal assimilation of magma suites in the East Greenland flood basalt province: tracking the evolution of magmatic systems2008Inngår i: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 102, nr 1-2, s. 179-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review published radiogenic isotope data (> 350 samples in total) on various suites of magmatic rocks within the Palaeogene central East Greenland flood basalt province to evaluate the types of crustal assimilants and the extent of crustal assimilation involved in each suite. We use these observations to build a regional picture of how magmatic plumbing systems changed with time and location during the sequential development of the province as magmatism responded to the development of a volcanic rifted margin and eventual plate separation. The earliest phase of magmatic activity (c. 62–57 Ma) is characterised by highly contaminated magmas that show a temporal change in assimilant type from amphibolite to granulite. This transition has been linked to the effects of an increasing magma supply rate which allows the more refractory granulite lithologies to be melted. The voluminous break-up phase of magmatism (c. 56–54 Ma) saw a significant decrease in the extent of assimilation because of the decreasing availability of assimilant material in the mature feeder systems, and many samples have Sr–Nd–Pb isotope compositions that overlap with those of asthenospheric melts (as represented by recent Icelandic basalts and North Atlantic MORB). Detailed study has allowed us to recognise packets of lavas that ponded at different levels in the crust and assimilated material of different compositions. The later stages of break-up magmatism show more diverse and more contaminated compositions that indicate a shift from a few large robust feeder systems to numerous small new conduits as the rifting continued. The post-break-up magmatism (c. 54–13 Ma) is characterised by a return to more highly contaminated magmas, which reflects a change in the style of magmatism: the eruption of small-volume alkalic lava flows from newly established conduits through the thicker inland crust, and the intrusion of mafic and silicic alkalic magmas at shallow levels in the Archaean basement along the present coast.

  • 38.
    Peate, David
    et al.
    Department of Geoscience, 121 Trowbridge Hall, University of Iowa, USA .
    Breddam, K
    Statens Institut for Strålehygiejne, Herlev, Denmark.
    Baker, Joel
    School of Geography, Environment and Earth Sciences, Victoria University of Wellington, New Zealan.
    Kurz, Mark
    Marine Chemistry & Geochemistry Department, Woods Hole Oceanographic Institution, USA .
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Prestvik, Tore
    Institute for Geology and Mineral Resources Engineering, Norwegian University of Science and Technology, Trondheim, Norway .
    Grassineau, Nathalie
    Department of Geology, Royal Holloway University of London, Egham, UK .
    Skovgaard, Anna Cecilie
    Danish Environmental Protection Agency, Copenhagen, Denmark .
    Compositional characteristics and spatial distribution of enriched Icelandic mantle components.2010Inngår i: Journal of Petrology, Vol. 51, nr 7, s. 1447-1475Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present compositional data on a suite of 18 primitive neovolcanic alkali basalts from three flank-zone regions in Iceland (Vestmannaeyjar in the south, Snæfell in the east, and Snæfellsnes in the west) that are peripheral to the main rift zones that are dominated by tholeiitic basalts. This study integrates He isotope data with radiogenic isotope data (Sr–Nd–Pb–Hf), stable isotope data (δ18O), and trace element data to characterize the compositional features of the trace element enriched components of the Icelandic mantle. We also present high-precision Pb isotope data on an additional 57 lava samples from the flank zones (including Öræfajökull in the SE) and the Northern and Eastern rift zones. Most Icelandic lavas have negative Δ207Pb (–4 to –1), with higher values (–1 to +4) found only in samples from Öræfajökull, Snæfell, and parts of the Reykjanes Peninsula. At Snæfell, this EM1-type component is characterized by a low δ18Oolivine signature (+4·1‰ to +4·6‰), moderate 206Pb/204Pb values (18·4–18·6) and mid-ocean ridge basalt (MORB)-like 3He/4He (6·9–7·5 R/RA). Samples from Vestmannaeyjar and Snæfellsnes have mantle-like δ18Oolivine (+4·9‰ to +5·0‰), and radiogenic 206Pb/204Pb values (18·9–19·3) that fall on the Northern Hemisphere Reference Line for 208Pb/204Pb (Δ208Pb –5 to +5). Compared with the Vestmannaeyjar lavas, Snæfellsnes lavas have higher La/YbN (5–11 vs 3–5), lower εNd (5·5–6·5 vs 6·8–7·6) and lower 3He/4He (6·3–8·6 R/RA vs 11·4–13·5 R/RA). Therefore, the most trace element enriched components in the Icelandic mantle are not the carriers of the high 3He/4He values (>15 R/RA) found in some lavas on Iceland and the adjacent ridges, and instead are consistent with degassed, recycled components. Even after excluding the EM1-type high Δ207Pb samples, high-precision Pb isotope data produce a kinked array on a 206Pb/204Pb vs 208Pb/204Pb plot, which is not consistent with simple binary mixing between two end-members. This requires significant lateral heterogeneity within the Icelandic mantle and the presence of more than just two compositionally distinct local mixing end-member components. Samples from each of the main axial rift zones define different trends. Despite the tectonic continuity between the Northern Volcanic Zone and the Eastern Volcanic Zone, lavas from these two rift zones define separate sub-parallel linear arrays. Lavas from the adjacent Western Volcanic Zone and the Eastern Volcanic Zone define oblique linear arrays that converge on a common local end-member that is not involved in the magmatism of the Northern Volcanic Zone. Therefore, there is a distinct NE–SW compositional heterogeneity within the Icelandic mantle.

  • 39.
    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-pumice2014Konferansepaper (Fagfellevurdert)
  • 40.
    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-pumice2014Konferansepaper (Fagfellevurdert)
  • 41.
    Rhodes, Emma
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Uppsala Univ, Ctr Nat Hazards & Disaster Sci, Uppsala, Sweden..
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Uppsala Univ, Ctr Nat Hazards & Disaster Sci, Uppsala, Sweden..
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Uppsala Univ, Ctr Nat Hazards & Disaster Sci, Uppsala, Sweden..
    Hieronymus, Christoph F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Rousku, S. N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    McGarvie, D. W.
    Univ Lancaster, Lancaster Environm Ctr, Lancaster, England..
    Mattsson, T.
    Univ St Andrews, Sch Earth & Environm Sci, St Andrews, Fife, Scotland.;Stockholm Univ, Dept Geol Sci, Stockholm, Sweden..
    Schmiedel, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Ronchin, E.
    Sapienza Univ Rome, Dept Earth Sci, Rome, Italy..
    Witcher, Taylor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Rapid Assembly and Eruption of a Shallow Silicic Magma Reservoir, Reyðarártindur Pluton, Southeast Iceland2021Inngår i: Geochemistry Geophysics Geosystems, E-ISSN 1525-2027, Vol. 22, nr 11, artikkel-id e2021GC009999Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although it is widely accepted that shallow silicic magma reservoirs exist, and can feed eruptions, their dynamics and longevity are a topic of debate. Here, we use field mapping, geochemistry, 3D pluton reconstruction and a thermal model to investigate the assembly and eruptive history of the shallow Reyoarartindur Pluton, southeast Iceland. Primarily, the exposed pluton is constructed of a single rock unit, the Main Granite (69.9-77.7 wt.% SiO2). Two further units are locally exposed as enclaves at the base of the exposure, the Granite Enclaves (67.4-70.2 wt.% SiO2), and the Quartz Monzonite Enclaves (61.8-67.3 wt.% SiO2). Geochemically, the units are related and were likely derived from the same source reservoir. In 3D, the pluton has a shape characterized by flat roof segments that are vertically offset and a volume of >2.5 km(3). The pluton roof is intruded by dikes from the pluton, and in two locations displays depressions associated with large dikes. Within these particular dikes the rock is partially to wholly tuffisitic, and rock compositions range from quartz monzonite to granite. We interpret these zones as eruption-feeding conduits from the pluton. A lack of cooling contacts throughout the pluton indicates rapid magma emplacement and a thermal model calculates the top 75 m would have rheologically locked up within 1,000 years. Hence, we argue that the Reyoarartindur Pluton was an ephemeral part of the wider plumbing system that feeds a volcano, and that timeframes from emplacement to eruption were rapid.

    Fulltekst (pdf)
    fulltext
  • 42.
    Rhodes, Emma
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Hieronymus, Christoph F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Geofysik.
    Rousku, Sabine
    McGarvie, Dave
    Mattsson, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Schmiedel, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Ronchin, Erika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Witcher, Taylor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Rapid formation and eruption of a silicic magma chamber2022Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Shallow magmatic reservoirs have been identified at many volcanoes worldwide. However, questions still remain regarding their size, dynamics and longevity. The Reyðarártindur Pluton exposed in Southeast Iceland provides a superb example to investigate the above questions. Here, we use field mapping, sampling, geochemistry, 3D pluton shape modelling and a numerical thermal model to reconstruct the assembly and eruptive history of the shallow magma body.

    In 3D, the c. 2.5 km3 pluton has a castle-like shape characterised by flat roof segments that are vertically offset along steep faults. The exposed pluton is constructed largely of a single rock unit, the Main Granite (69.9 to 77.6 wt.% SiO2). Two additional units occur only as enclaves: the Granite Enclaves (67.4 to 70.2 wt.% SiO2), and the Quartz Monzonite Enclaves (61.8 to 67.3 wt.% SiO2). However, geochemistry clearly indicates that the units are related and hence were likely derived from the same source reservoir. 

    In two locations, the pluton roof displays depressions associated with large dykes. Within these two dykes the rock is partially to wholly tuffisitic, and geochemical compositions range from quartz monzonite to granite. We interpret these dykes as eruption-feeding conduits from the pluton. Additionally, we speculate that the mingling of magmatic units with compositional ranges from quartz monzonite to granite within the conduits indicates that injection of new magma into the reservoir triggered eruption. 

    Rapid pluton construction is indicated by ductile contacts between units in the pluton and a thermal model calculates the top 75 m would have rheologically locked up within 1000 years. Hence, we argue that the pluton was a short-lived part of the wider magmatic system that fed the associated volcano, and that timeframes from emplacement to eruption were limited to 1000 years.

    Rhodes, E. Barker, A. K. Burchardt, S. et al. (2021). Rapid assembly and eruption of a shallow silicic magma reservoir, Reyðarártindur Pluton, Southeast Iceland. G-Cubed. DOI: 10.1029/2021GC009999

  • 43.
    Rhodes, Emma
    et al.
    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.
    Barker, Abigail
    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.
    Ronchin, Erika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Schmiedel, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Witcher, Taylor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Insights into the magmatic processes of a shallow, silicic storage zone: Reyðarártindur Pluton, Iceland2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Reyðarártindur is one of several felsic plutons exposed in Southeast Iceland, interpreted to be the shallow plumbing systems of late Neogene volcanic centres (Cargill et al., 1928; Furman et al., 1992; Padilla, 2015). These plutons are considered to preserve analogous plumbing systems to the central volcanoes active in Iceland today (Furman et al., 1992). Reyðarártindur is the oldest pluton in Southeast Iceland at 7.30 ± 0.06 Ma (Padilla, 2015), and has been conveniently incised by the Reyðará River, making it ideal for an in-depth study of the external and internal geometry of a shallow rift-zone magma plumbing system.

    In order to analyse mechanisms of magma emplacement, we have conducted detailed structural mapping of the pluton and its basaltic host rock using drone-based photogrammetry. To complement this, we have also extensively sampled and analysed the geochemistry and petrology of the pluton interior. An outline of the pluton is shown in Figure 1, highlighting that the pluton is NNW-SSE trending, which is in contrast to the NE-SW regional dyke trend. A total thickness of 500 m and a calculated volume of 1.5 km3 is exposed. While the pluton walls are steeply-dipping, the pluton roof is mostly flat. Deviations from the flat roof occur in the form of areas that are cut by steep dip-slip faults with displacements of up to 100 m. Roof faulting creates both structural highs (horsts) and lows (grabens, as well as a monoclinal structure) in the roof. Many of the faults are intruded by felsic dykes, some of them seem to have been the feeders of surface eruptions.

    An estimated 95% of the pluton volume is rhyolitic in composition, with 73-76 wt.% SiO2. Geochemically, the magma in the majority of the pluton is similar, but hand samples and thin sections show a large variety of textures. In the lower part of the exposure there is a zone of mingling and mixing between a matrix magma and several different types of silicic enclaves (Figure 1). The matrix magma is more mafic with an SiO2 content of 68-73 wt.% and the enclaves vary in nature with no systematic shape, size or aspect ratio. There are at least two types of enclaves, and the predominant type is a coarse grained trachydacite with 64-69 wt.% SiO2. These less evolved compositions are limited to a 1 km stretch of the riverbed in the centre of the pluton. Closer to the wall contacts (i.e. to the north and south of the mingling zone), the composition of the magma returns to that of the main magma body, as observed at higher elevations.

    Our poster aims to summarise our results and present interpretations of the magmatic processes preserved in the Reyðarártindur pluton. Our preliminary results indicate that the pluton was emplaced by a combination of floor subsidence and roof doming, and that the pluton structure was modified during further magma intrusion into, and eruption from, the pluton.

     Fig. 1 – Map of the Reyðarártindur Pluton, South-East Iceland.

     

    References

     

    Cargill, H., Hawkes, L., and Ledeboen, J. (1928). The major intrustions of South-Eastern Iceland. Quarterly Journal of the Geological Society of London 84, 505–539.

    Furman, T., Meyer, P. S., and Frey, F. (1992). Evolution of Icelandic central volcanoes: evidence from the Austurhorn intrusion, southeastern Iceland. Bulletin of Volcanology. 55, 45–62.

    Padilla, A. (2015). Elemental and isotopic geochemistry of crystal-melt systems: Elucidating the construction and evolution of silicic magmas in the shallow crust, using examples from southeast Iceland and southwest USA [PhD Dissertation: Vanderbilt University].

     

  • 44.
    Rhodes, Emma
    et al.
    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.
    Greiner, Sonja H. M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Mattsson, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Sigmundsson, Freysteinn
    University of Iceland.
    Schmiedel, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. TU Delft.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre for Natural Disaster Science (CNDS), Uppsala University, Villavägen 16, 75236 Uppsala, Sweden.
    Witcher, Taylor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Volcanic unrest as seen from the magmatic source: Reyðarártindur pluton, Iceland2024Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 14, artikkel-id 962Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Rhodes, Emma
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre for Natural Hazards and Disaster Science, Sweden.
    Burchardt, Steffi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre for Natural Hazards and Disaster Science, Sweden.
    Parker, Charles F.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Statsvetenskapliga institutionen. Centre for Natural Hazards and Disaster Science, Sweden.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik. Centre for Natural Hazards and Disaster Science, Sweden.
    Dahrén, Börje
    Uppsala universitet, Universitetsbiblioteket.
    What is the role of Wiki during volcanic eruptions?2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

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

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

    Fulltekst (pdf)
    Wikimania 2019 - volcanoes and wiki
  • 46. Tamura, Y.
    et al.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Busby, C.J.
    Izu-Bonin-Mariana Rear Arc - The missing half of the subduction factory, 30 March – 30 May 20142014Rapport (Fagfellevurdert)
    Abstract [en]

    International Ocean Discovery Program (IODP) Hole U1436A (proposed Site IBM-4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, 1.5 km west of Ocean Drilling Program (ODP) Site 792, and at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including distinctive black glassy mafic ash layers that may record large-volume eruptions on the Izu arc front. Because of the importance of this discovery, Site U1436 was drilled in three additional holes (U1436B, U1436C, and U1436D), as part of a contingency operation, in an attempt to get better recovery on the black glassy mafic ash layers and enclosing sediments and to better constrain the thickness of the mafic ash layers.IODP Site U1437 is located in the Izu rear arc, ~330 km west of the axis of the Izu-Bonin Trench and ~90 km west of the arc-front volcanoes Myojinsho and Myojin Knoll, at 2117 mbsl. The primary scientific objective for Site U1437 was to characterize “the missing half of the subduction factory”; this was because numerous ODP/Integrated Ocean Drilling Program sites had been drilled in the arc to fore-arc region (i.e., ODP Site 782A Leg 126), but this was the first site to be drilled in the rear part of the Izu arc. A complete view of the arc system is needed to understand the formation of oceanic arc crust and its evolution into continental crust. Site U1437 on the rear arc had excellent core recovery in Holes U1437B and U1437D, and we succeeded in hanging the longest casing ever in the history of R/V JOIDES Resolution scientific drilling (1085.6 m) in Hole U1437E and cored to 1806.5 mbsf.The stratigraphy at Site U1437 was divided into seven lithostratigraphic units (I–VII) that were distinguished from each other based on the proportions and characteristics of tuffaceous mud/mudstone and interbedded tuff, lapilli tuff, and tuff breccia. The section is much more mud rich than expected, with ~60% tuffaceous mud for the section as a whole (89% in the uppermost 433 m) and high sedimentation rates of 100–260 m/My for the upper 1320 m (Units I–V). The proportion (40%) and grain size of tephra are much smaller than expected for an intra-arc basin, composed half of ash/tuff and half of lapilli tuff of fine grain size (clasts < 3 cm). These were deposited by suspension settling through water and from density currents, in relatively distal settings. Volcanic blocks are only sparsely scattered through the lowermost 25% of thesection (Units VI and VII, 1320–1806.5 mbsf), which includes hyaloclastite, in situ quench-fragmented blocks, and a rhyolite peperite intrusion (i.e., proximal deposits). The transition from unconsolidated to lithified rocks occurred progressively; however, sediments were considered lithified from 427 mbsf (top of Hole U1437D) downward. Alteration resulted in destruction of fresh glass from ~750 mbsf downward, but minerals are less altered. Because of the alteration, the deepest biostratigraphic datum was at ~850 mbsf and the deepest paleomagnetic datum was at ~1300 mbsf. Additional age control deeper than this depth is provided by an age range of 10.97–11.85 Ma inferred from a nannofossil assemblage at ~1403 mbsf and a preliminary U-Pb zircon concordia intercept age of 13.6 +1.6/–1.7 Ma, measured postcruise on a rhyolite peperite in Unit VI at ~1390 mbsf.Based on the seismic profiles, the Miocene–Oligocene hiatus (~17–23 Ma) was predicted to lie at ~1250 mbsf, but strata at that depth (Unit V, 1120–1312 mbsf) are much younger (~9 Ma), indicating that we recovered a thicker Neogene section of volcaniclastics and associated igneous rocks than anticipated. Our preliminary interpretation of shipboard geochemistry is that arc-front versus rear-arc sources can be distinguished in the upper, relatively distal 1320 m of section (Units I–V), whereas the lower, proximal 25% of the section (Units VI–VII) may be geochemically heterogeneous, suggesting that the rear-arc magmas only fully compositionally diverged after ~13 Ma.

  • 47.
    Tamura, Yoshihiko
    et al.
    Research and Development Center for Ocean Drilling Science.
    Busby, Cathy J.
    University of California, Santa Barbara.
    Blum, Peter
    Texas A&M University.
    Barker, Abigail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Mineralogi, petrologi och tektonik.
    Proceedings of the International Ocean Discovery Program, Expedition 350: Izu-Bonin-Mariana Rear Arc2015Rapport (Annet vitenskapelig)
  • 48.
    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 hotspot2015Inngår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, nr 4, s. 137-145Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 49.
    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 Zone2013Inngår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 75-92Kapittel i bok, del av antologi (Fagfellevurdert)
    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.

  • 50.
    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 gardening2017Inngår i: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 33, nr 4, s. 148-154Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
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