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  • 151.
    Wiesmaier, Sebastian
    et al.
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Ellam, Robert M.
    Scottish Universities Environmental Research Centre (SUERC), East Kilbride, Scotland, UK.
    Bindemann, Ilya
    Department of Geological Sciences, University of Oregon, Eugene, OR, USA.
    Wolff, John A.
    Department of Geology, Washington State University, Pullman, WA, USA.
    Deegan, Frances
    Magmatic Differentiation in the Teide–Pico Viejo Succession: Isotope Analysis as a Key to Deciphering the Origin of Phonolite Magma2013Ingår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 173-190Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In Tenerife, lavas of the recent Teide–Pico Viejo central complex show a marked bimodality in composition from initially mafic lava (200–30 ka) to highly differentiated phonolite (30–0 ka). Groundmass Sr–Nd–Pb–O and feldspar 18O data demonstrate open system behaviour for the petrogenesis of Teide–Pico Viejo felsic lavas, but contamination by ocean sediment can be excluded due to the low 206Pb/204Pb ratios of North Atlantic sediment. Isotope mixing hyperbolae require an assimilant of predominantly felsic composition for the Teide–Pico Viejo succession. Unsystematic and heterogeneous variation of 18O in fresh and unaltered feldspars across the Teide–Pico Viejo succession indicates magmatic addition of diverse 18O assimilants, best matched by nepheline syenites that occur as fresh and altered lithic blocks in voluminous pre-Teide ignimbrite deposits. Rare earth element modelling indicates that nepheline syenite needs to be melted in bulk to form a suitable end-member composition. Energy-Constrained Assimilation Fractional Crystallisation (EC-AFC) modelling reproduces the bulk of the succession, which implies that the petrogenesis of Teide–Pico Viejo lavas is governed by the coupled assimilation of nepheline syenite during fractional crystallisation. The most differentiated (and most radiogenic) lava computes to >97.8 % assimilant, likely represented by a nepheline syenite bulk melt that formed by underplating with juvenile mafic material. These recent research developments therefore recognise a wider variability of magmatic differentiation processes at Teide–Pico Viejo than previously considered.

  • 152. Wiesmaier, Sebastian
    et al.
    Troll, Valentin R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Wolff, John A.
    Carlos Carracedo, Juan
    Open-system processes in the differentiation of mafic magma in the Teide-Pico Viejo succession, Tenerife2013Ingår i: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 170, nr 3, s. 557-570Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oceanic island basalts are commonly thought to differentiate by fractional crystallization, yet closed-system fractionation models have so far failed to reproduce major and trace element variations observed in mafic lavas from the Teide-Pico Viejo stratovolcano complex on Tenerife. Here, new high-precision plagioclase trace element data are fed into such a fractionation model. The results confirm that fractionation of phenocrysts found in the lavas does not reproduce trace element variations, in particular enrichment of Sr and Zr observed in the Teide-Pico Viejo mafic suite. This enrichment of Sr and Zr is tested by an energy-constrained recharge, assimilation and fractional crystallization (EC-RAFC) model at high T and low Lambda T intervals, consistent with previously determined magma storage beneath Tenerife at sub-Moho depths. Published mineral-melt equilibrium relations using the plagioclase anorthite content (0.4 < X-An < 0.8) constrain the temperature during differentiation. Gabbroic xenoliths found in Tenerife lavas are assumed as contaminant. Enrichment of Sr and Zr in the Teide mafic suite is reproduced by this combined assimilation and fractional crystallization model, as assimilation causes higher degrees of enrichment in incompatible trace elements than is possible by crystal fractionation alone. Recycling of plutonic roots may thus have significantly enriched trace elements in the primitive lavas of the Teide-Pico Viejo succession.

  • 153.
    Wiesmaier, Sebastian
    et al.
    Department of Earth and Environmental Sciences, Ludwig-Maximilians Universität (LMU), Munich, Germany.
    Troll, Valentin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Berggrundsgeologi.
    Rodríguez-Badiola, Eduardo
    Museo Nacional de Ciencias Naturales del CSIC, Madrid, Spain.
    Carracedo, Juan Carlos
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Timing, Distribution and Petrological Evolution of the Teide-Pico Viejo Volcanic Complex2013Ingår i: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, s. 155-172Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Several cycles of initially mafic to progressively felsic activity have given rise to large volume felsic deposits on Tenerife that serve as prime examples of pronounced magmatic differentiation in an ocean island setting. The Teide–Pico Viejo succession is the most recent of these cycles to show a systematic evolution from initially basanitic to phonolitic eruptions. Basanite lava flows bear olivine, pyroxene and occasionally plagioclase, while phonolites mainly display alkali feldspar with subordinate pyroxene, amphibole, biotite and oxides. Three groups of eruptives can be discerned based on their trace element composition: (1) Mafic lavas that show typical OIB signatures, (2) Transitional lavas, which are enriched in incompatible trace elements but may be depleted in Ba and Sr and (3) Phonolites, which are more enriched in incompatible trace elements, but show the strongest negative Ba and Sr anomalies. Linking the spatio-chronological distribution of eruptions with these compositional groups shows a progressive migration of mafic activity from the outskirts of the rift zones towards the central complex over the last 30 ka. The arrival of mafic activity at the central complex coincided with the onset of more evolved eruptions at Teide, thought to be triggered by mafic underplating. The distribution of mafic activity at the surface may thus be related to the volume of mafic underplating beneath the volcanic edifice at a given time.

  • 154.
    Zaczek, Kirsten
    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.
    Cachao, Mario
    Ferreira, Jorge
    Deegan, Frances
    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.
    Soler, Vincente
    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, Mineralogi, petrologi och tektonik.
    Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands2015Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, s. 7945-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

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