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  • 1
    Artikel
    Artikel
    Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands, (2005)
    Dazugehörige Bände
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    In: Bulletin of volcanology, Berlin : Springer, 1986, 67(2005), Seite 281-291, 0258-8900
    In: volume:67
    In: year:2005
    In: pages:281-291
    Materialart: Artikel
    ISSN: 0258-8900
    Sprache: Englisch
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  • 2
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    Petrology and geochemistry of igneous inclusions in recent Merapi deposits: a window into the sub-volcanic plumbing system (2013)
    Springer
    In:  Contributions to Mineralogy and Petrology, 165 (2). pp. 259-282.
    Details
    Publikationsdatum: 2016-09-21
    Beschreibung: Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, geochemistry and geobarometric calculations. The inclusions may be classified into four main suites: (1) highly crystalline basaltic-andesite inclusions, (2) co-magmatic enclaves, (3) plutonic crystalline inclusions and (4) amphibole megacrysts. Highly crystalline basaltic-andesite inclusions and co-magmatic enclaves typically display liquid–liquid relationships with their host rocks, indicating mixing and mingling of distinct magmas. Co-magmatic enclaves are basaltic in composition and occasionally display chilled margins, whereas highly crystalline basaltic-andesite inclusions usually lack chilling. Plutonic inclusions have variable grain sizes and occasionally possess crystal layering with a spectrum of compositions spanning from gabbro to diorite. Plagioclase, pyroxene and amphibole are the dominant phases present in both the inclusions and the host lavas. Mineral compositions of the inclusions largely overlap with compositions of minerals in recent and historic basaltic-andesites and the enclaves they contain, indicating a cognate or ‘antelithic’ nature for most of the plutonic inclusions. Many of the plutonic inclusions plot together with the host basaltic-andesites along fractional crystallisation trends from parental basalt to andesite compositions. Results for mineral geobarometry on the inclusions suggest a crystallisation history for the plutonic inclusions and the recent and historic Merapi magmas that spans the full depth of the crust, indicating a multi-chamber magma system with high amounts of semi-molten crystalline mush. There, crystallisation, crystal accumulation, magma mixing and mafic recharge take place. Comparison of the barometric results with whole rock Sr, Nd, and Pb isotope data for the inclusions suggests input of crustal material as magma ascends from depth, with a significant late addition of sedimentary material from the uppermost crust. The type of multi-chamber plumbing system envisaged contains large portions of crystal mush and provides ample opportunity to recycle the magmatic crystalline roots as well as interact with the surrounding host lithologies.
    Materialart: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1007/s00410-012-0808-7
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  • 3
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    Corrigendum to "Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption" published in Solid Earth, 3, 97–110, 2012 (2012)
    Copernicus Publications (EGU)
    In:  Solid Earth, 3 (2). p. 189.
    Details
    Publikationsdatum: 2016-09-05
    Materialart: Article , NonPeerReviewed
    Format: text
    DOI: 10.5194/se-3-189-2012
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  • 4
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    The problem of caldera ellipticity (2005)
    In:  [Other] In: EGU General Assembly 2005, 24.-29.04, Vienna, Austria .
    Details
    Publikationsdatum: 2012-02-23
    Materialart: Conference or Workshop Item , NonPeerReviewed
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  • 5
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    Ultramafic volcanism associated with the El Golfo giant lateral collapse, El Hierro, Canary Islands (2006)
    In:  [Poster] In: AGU Fall Meeting 2006, 11.-15.12, San Francisco, USA .
    Details
    Publikationsdatum: 2012-02-23
    Materialart: Conference or Workshop Item , NonPeerReviewed
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  • 6
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    The REE-Ti mineral chevkinite in comenditic magmas from Gran Canaria, Spain: a SYXRF-probe study (2003)
    Springer
    In:  Contributions to Mineralogy and Petrology, 145 (6). pp. 730-741.
    Details
    Publikationsdatum: 2016-09-21
    Beschreibung: The REE-Ti silicate chevkinite has been recognised previously in Miocene ignimbrites from Gran Canaria, and in correlative offshore syn-ignimbrite turbidites. We have estimated the partition coefficients of REE, Y, Zr and Nb for chevkinite and co-existing peralkaline rhyolitic (comendite) glass using synchrotron-XRF-probe analyses (SYXRF) in order to evaluate the role of this mineral in the REE budget of felsic peralkaline magmas. The Zr/Nb ratio of the chevkinite is 1.55–1.7, strongly contrasting with Zr/Nb of 6.5 in the associated glass. Zr shows a three-fold enrichment in chevkinite relative to the residual melt, whereas Nb is enriched by a factor 〉10. The enrichment of Ce and La in chevkinite is even more significant, namely 19 wt(%) Ce and 12 wt(%) La, compared to 236 ppm Ce and 119 ppm La in the glass. Chevkinite/glass ratios are 988±30 for La, 806±30 for Ce, 626±30 for Pr, 615±40 for Nd, 392±50 for Sm, 225±30 for Eu, 142±25 for Gd, 72±20 for Dy. For trace elements, we derived KdTE of 74±25 for Y, 〉8 for Hf, 〉50 for Th, 15±5 for Nb and 3.55±0.4 for Zr. Mineral/glass ratios for co-existing titanite are 28±10 for La, 86±20 for Ce, 98±30 for Pr, 134±35 for Nd, 240±50 for Sm, 50±20 for Eu, 96±25 for Gd, 82±25 for Dy, 99±30 for Y, 45±10 for Nb and 3±0.5 for Zr. Based on these data, the removal of only 0.05 wt% of chevkinite from a magma with initially 300 ppm Ce would deplete the melt by 93 ppm to yield 207 ppm Ce in the residual liquid. Chevkinite thus appears, when present, to be the controlling mineral within the LREE budget of evolved peralkaline magmas.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00410-003-0475-9
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  • 7
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    Upper mantle magma storage and transport under a Canarian shield-volcano, Teno, Tenerife (Spain) (2008)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Solid Earth, 113 . B08203.
    Details
    Publikationsdatum: 2018-04-25
    Beschreibung: We use clinopyroxene-liquid thermobarometry, aided by petrography and mineral major element chemistry, to reconstruct the magma plumbing system of the late Miocene, largely mafic Teno shield-volcano on the island of Tenerife. Outer rims of clinopyroxene and olivine phenocrysts show patterns best explained by decompression-induced crystallization upon rapid ascent of magmas from depth. The last equilibrium crystallization of clinopyroxene occurred in the uppermost mantle, from ∼20 to 45 km depth. We propose that flexural stresses or, alternatively, thermomechanical contrasts create a magma trap that largely confines magma storage to an interval roughly coinciding with the Moho at ∼15 km and the base of the long-term elastic lithosphere at ∼40 km below sea level. Evidence for shallow magma storage is restricted to the occurrence of a thick vitric tuff of trachytic composition emplaced before the Teno shield-volcano suffered large-scale flank collapses. The scenario developed in this study may help shed light on some unresolved issues of magma supply to intraplate oceanic volcanoes characterized by relatively low magma fluxes, such as those of the Canary, Madeira and Cape Verde archipelagoes, as well as Hawaiian volcanoes in their postshield stage. The data presented also support the importance of progressive magmatic underplating in the Canary Islands.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2007JB005422
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  • 8
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    Bimodality of Lavas in the Teide-Pico Viejo Succession in Tenerife--the Role of Crustal Melting in the Origin of Recent Phonolites (2012)
    Oxford University Press
    Details
    Publikationsdatum: 2012-11-21
    Beschreibung: In Tenerife, lavas of the recent Teide–Pico Viejo central complex show a marked bimodality in composition from initially mafic lavas (200–30 ka) to highly differentiated phonolites (30–0 ka). After this abrupt change, the bimodality of the lavas continued to manifest itself between the now felsic Teide–Pico Viejo central complex and the adjacent, but exclusively mafic, rift zones. Whole-rock trace element fingerprinting distinguishes three compositional groups (mafic, transitional, felsic). Groundmass Sr–Nd–Pb–O and feldspar 18 O data demonstrate open-system behaviour for the petrogenesis of the Teide–Pico Viejo felsic lavas by high 87 Sr/ 86 Sr ratios of up to 0·7049, uniform 206 Pb/ 204 Pb (19·75–19·78), variable 207 Pb/ 204 Pb (15·53–15·62) and heterogeneous 18 O values (5·43–6·80). However, ocean sediment contamination can be excluded because of the low 206 Pb/ 204 Pb ratios of North Atlantic sediments. Isotope mixing hyperbolae reproduce the entire Teide–Pico Viejo succession and require an assimilant of predominantly felsic composition. Unsystematic and heterogeneous variation of 18 O in fresh and unaltered feldspars across the Teide–Pico Viejo succession indicates magmatic addition of diverse 18 O assimilants, altered near surface at high and low temperatures. The best fit for these requirements is provided by nepheline syenite that occurs as fresh or altered lithic blocks in voluminous pre-Teide ignimbrite deposits and is similarly heterogeneous in oxygen isotope composition. Nepheline syenite blocks are considered to represent deep remnants of associated earlier eruptions and were thus available for assimilation at depth. Rare earth element modelling indicates that nepheline syenite needs to be melted in bulk to form a suitable end-member composition. Using this assimilant, energy-constrained assimilation fractional crystallization (EC-AFC) modelling reproduces the bulk of the succession, which leads us to suggest that Teide–Pico Viejo petrogenesis is governed by assimilation and fractional crystallization. Both mixing hyperbolae and EC-AFC models indicate that assimilation is more pronounced for the more felsic lavas. The maximum assimilation is evident in the most strongly differentiated (and the most radiogenic in Sr) lava and computes to 〉97·8% of the assimilant. This most evolved eruption probably represents nepheline syenite bulk melts that formed spatially decoupled from juvenile material. This study therefore recognizes a wider variability of magmatic differentiation processes at Teide–Pico Viejo than previously thought.
    Print ISSN: 0022-3530
    Digitale ISSN: 1460-2415
    Thema: Geologie und Paläontologie
    Publiziert von Oxford University Press
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  • 9
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    Crustal Differentiation Processes at Krakatau Volcano, Indonesia (2012)
    Oxford University Press
    Details
    Publikationsdatum: 2012-12-21
    Beschreibung: Anak Krakatau is a basaltic andesite cone that has grown following the famous caldera-forming 1883 eruption of Krakatau. It breached sea level in 1927 and since the 1950s has been growing at an average rate of ~8 cm a week. We present new major and trace element data combined with whole-rock 18 O, Sr and Nd isotope data for 1883, 1993 and 2002 Krakatau eruptive products and the surrounding crust. Bombs erupted from Anak Krakatau during 2002 contain frothy metasedimentary and plutonic xenoliths that show variable degrees of thermal metamorphism, plastic deformation and partial melting. Contact-metamorphic minerals such as cordierite and tridymite in metasedimentary xenoliths are consistent with high-temperature metamorphism and incorporation at mid- to upper-crustal depth. Energy-constrained assimilation and fractional crystallization modelling of whole-rock data suggests that the Anak Krakatau magmas have a genetic relationship with the 1883 eruption products. The geochemical impact of crustal contaminants on whole-rock compositions is apparently small, and we conclude that low levels of assimilation of a quartzo-feldspathic sediment are recorded in Anak Krakatau magmas. Plagioclase phenocrysts from the 2002 eruption exhibit disequilibrium textures and complex compositional zoning, however, and are also isotopically variable with a total range in 87 Sr/ 86 Sr of 0·7043–0·7048 as determined by in situ laser ablation inductively coupled plasma mass spectrometry. This suggests that although shallow crustal assimilation appears to have had a limited effect on whole-rock chemistry, a complex late-stage differentiation history is recorded within the magma’s cargo of crystals and xenoliths.
    Print ISSN: 0022-3530
    Digitale ISSN: 1460-2415
    Thema: Geologie und Paläontologie
    Publiziert von Oxford University Press
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  • 10
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    Volatile dilution during magma injections and implications for volcano explosivity (2016)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publikationsdatum: 2016-11-19
    Beschreibung: Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H 2 O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal scale. H 2 O contents within melt inclusions range from ~0.45 to 2.27 wt% and do not correlate with melt inclusion size or distance from the crystal rim, suggesting that minimal H 2 O was lost via diffusion. Instead, inclusion H 2 O contents vary systematically with anorthite content of the host plagioclase (R 2 = 0.51), whereby high anorthite content zones are associated with low H 2 O contents and vice versa. This relationship suggests that injections of hot and H 2 O-poor magma can increase the reservoir temperature, leading to the dilution of melt H 2 O contents. In addition to recording hot and H 2 O-poor conditions after these injections, plagioclase crystals also record relatively cold and H 2 O-rich conditions such as prior to the explosive 2014 eruption. In this case, the elevated H 2 O content and increased viscosity may have contributed to the high explosivity of the eruption. The point at which an eruption occurs within such repeating hot and cool cycles may therefore have important implications for explaining alternating eruptive styles.
    Print ISSN: 0091-7613
    Digitale ISSN: 1943-2682
    Thema: Geologie und Paläontologie
    Publiziert von Geological Society of America (GSA)
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