310 research outputs found
Encapsulation of vitamin E in yogurt-based beverage emulsions : Influence of bulk pasteurization and chilled storage on physicochemical stability and starter culture viability
No full textThis research was funded by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS). Author Contributions Conceptualization, V.R.; methodology, V.R., H.E.H., L.P.P. and S.G.; formal analysis, H.E.H.; data curation, H.E.H. and V.R.; writing—original draft preparation, V.R. and H.E.H.; supervision, V.R. and H.E.H.; funding acquisition, V.R. All authors have read and agreed to the published version of the manuscript.Peer reviewe
Strontium isotope systematics of experimentally produced melts: understanding magma-carbonate interaction at Merapi volcano, Indonesia
No full textThere is considerable evidence for ongoing, late-stage interaction between the magmatic system at Merapi volcano, Indonesia, and local crustal carbonate. In order to resolve the interaction processes in detail, we have performed a series of time-variable carbonate dissolution experiments in silicate melt using Merapi basaltic-andesite and local limestone as starting materials, at magmatic pressure and temperature. Major element profiling of the experimental products has identified strongly contrasting compositional domains of glass: a Ca-enriched zone containing up to 36 wt% CaO, and an unaffected, Ca-normal zone containing 8 to 10 wt% CaO.
To investigate the systematics of strontium isotopes and trace elements (TE) during carbonate assimilation, we have used micro-sampling and high-precision analytical techniques to measure 87Sr/86Sr ratios and TE concentrations over the magma-carbonate and intra-melt interfaces in two of our experimental products. The isotope variation between the different glass compositions is distinct, with 87Sr/86Sr ranging from 0.705641 in the Ca-normal glass to 0.706532 in the Ca-enriched glass. The upper end of this range is considerably more radiogenic than the range reported for Merapi whole rock volcanic products (0.70501 to 0.70583, Gertisser & Keller, 2003 J Pet, 44, 457-489). Our data hence support a model of assimilation of crustal carbonate with highly radiogenic 87Sr/86Sr (0.708799) at Merapi volcano. Given that the starting materials used in the experiments have markedly distinct 87Sr/86Sr values we here present new and detailed insights about the behaviour of Sr isotopes during carbonate assimilation, with a focus on the processes that operate across the carbonate-melt interface and the intra-melt transitions. Strontium is a reliable tracer of magma-crust interaction and so we anticipate that our results will significantly help to quantify our comprehension of magma-carbonate interaction processes occurring at Merapi volcano.PublishedDavos, Switzerland2.3. TTC - Laboratori di chimica e fisica delle rocceope
Strontium isotope systematics of experimentally produced melts: understanding magma-carbonate interaction at Merapi volcano, Indonesia
No full textThere is considerable evidence for ongoing, late-stage interaction between the magmatic system at Merapi volcano, Indonesia, and local crustal carbonate. In order to resolve the interaction processes in detail, we have performed a series of time-variable carbonate dissolution experiments in silicate melt using Merapi basaltic-andesite and local limestone as starting materials, at magmatic pressure and temperature. Major element profiling of the experimental products has identified strongly contrasting compositional domains of glass: a Ca-enriched zone containing up to 36 wt% CaO, and an unaffected, Ca-normal zone containing 8 to 10 wt% CaO.
To investigate the systematics of strontium isotopes and trace elements (TE) during carbonate assimilation, we have used micro-sampling and high-precision analytical techniques to measure 87Sr/86Sr ratios and TE concentrations over the magma-carbonate and intra-melt interfaces in two of our experimental products. The isotope variation between the different glass compositions is distinct, with 87Sr/86Sr ranging from 0.705641 in the Ca-normal glass to 0.706532 in the Ca-enriched glass. The upper end of this range is considerably more radiogenic than the range reported for Merapi whole rock volcanic products (0.70501 to 0.70583, Gertisser & Keller, 2003 J Pet, 44, 457-489). Our data hence support a model of assimilation of crustal carbonate with highly radiogenic 87Sr/86Sr (0.708799) at Merapi volcano. Given that the starting materials used in the experiments have markedly distinct 87Sr/86Sr values we here present new and detailed insights about the behaviour of Sr isotopes during carbonate assimilation, with a focus on the processes that operate across the carbonate-melt interface and the intra-melt transitions. Strontium is a reliable tracer of magma-crust interaction and so we anticipate that our results will significantly help to quantify our comprehension of magma-carbonate interaction processes occurring at Merapi volcano.PublishedDavos, Switzerland2.3. TTC - Laboratori di chimica e fisica delle rocceope
An overview of the large-magnitude (VEI 4) eruption of Merapi in 2010
No full textThe VEI 4 eruption in 2010 was the worst volcanic disaster at Merapi in 80 years.The unusual size and dynamics of the eruption, the rapid acceleration of events and the large number of evacuees posed significant challenges for the management of the volcanic crisis and post-eruption recovery. The first indications of Merapi’s reawakening were observed in the seismic monitoring record about one year before the eruption. The eruption commenced on 26 October 2010, with initial explosions and associated pyroclastic density currents (PDCs) directed towards the south flank of Merapi. Subsequently, the intensity of the eruption accelerated with rapid lava dome growth and increasing PDC runout, culminating in a climactic eruption phase on 5 November, where blast-like, high-energy PDCs destroyed areas on Merapi’s south flank and PDCs reached ~16 km in the Gendol valley. After 5 November, the eruption waned, leading to reductions of the exclusion zone from mid-November 2010 and successive lowering of the alert level from early December 2010. The 2010 eruption was fed by basaltic andesite magma similar to other recent Merapi eruptions, but was driven by a larger than normal influx of deep, volatile-rich magma that replenished the shallower magma system within the carbonate-dominated upper crust beneath Merapi at relatively short timescales. During and after the eruption, lahars swept down almost all major valleys, causing considerably larger impact than after previous eruptions. As a result of the eruption, nearly 400,000 people were displaced from their homes and accommodated in temporary or permanent residences. Tourist activities and sand quarrying of PDC and lahar deposits facilitated post-eruption recovery. Mitigation measures, including strengthening of the volcano monitoring system, establishment of a disaster risk reduction forum, strengthening of community capacity, and preparation of contingency plans for local governments based on hazard scenarios, were all part of the disaster risk reduction strategy that saved many lives during the 2010 eruption crisis.</p
Oxygen isotope composition of xenoliths from the oceanic crust and volcanic edifice beneath Gran Canaria (Canary Islands): consequences for crustal contamination of ascending magmas
No full textXenolith samples of marine terrigenous sediments and altered Jurassic MORB from Gran Canaria (Canary Islands) represent samples of sub-island oceanic crust. These samples are postulated to define end-members for crustal contamination of basaltic and felsic ocean island magmas. The meta-igneous rocks show great heterogeneity in oxygen isotope compositions (δ18O 3.3–8.6‰), broadly correlating with their stratigraphic position in the oceanic crust. Gabbros interpreted as fragments of oceanic crust layer 3 have δ18O values of 3.3–5.1‰, which is lower than MORB (5.7–6.0‰). Layer 2 lavas and dykes show a broader range of δ18O of 4.1–8.6‰. Therefore, high-temperature metamorphism seems to have been the dominant process in layer 3, while both high- and low-temperature alteration have variably affected layer 2 rocks. Siliciclastic sediments have high δ18O values (14.1–16.4‰), indicating diagenesis and low-temperature interaction with seawater. The oxygen isotope stratigraphy of the crust beneath Gran Canaria is typical for old oceanic crust and resembles that in ophiolites. The lithologic boundary between older oceanic crust and the igneous core complex at 8–10 km depth—as postulated from geophysical data—probably coincides with a main magma stagnation level. There, the Miocene shield phase magmas interacted with preexisting oceanic crust. We suggest that the range in δ18O values (5.2–6.8‰) [Chem. Geol. 135 (1997) 233] found for shield basalts on Gran Canaria, and those in some Miocene felsic units (6.0–8.5‰), are best explained by assimilation of various amounts and combinations of oceanic and island crustal rocks and do not necessarily reflect mantle source characteristics
Trace element and isotope constraints on crustal anatexis by upwelling mantle melts in the North Atlantic Igneous Province: an example form the Isle of Rum, NW Scotland
No full textSr and Nd isotope ratios, together with lithophile trace elements, have been measured in a representative set of igneous rocks and Lewisian gneisses from the Isle of Rum in order to unravel the petrogenesis of the felsic rocks that erupted in the early stages of Palaeogene magmatism in the North Atlantic Igneous Province (NAIP). The Rum rhyodacites appear to be the products of large amounts of melting of Lewisian amphibolite gneiss. The Sr and Nd isotopic composition of the magmas can be explained without invoking an additional granulitic crustal component. Concentrations of the trace element Cs in the rhyodacites strongly suggests that the gneiss parent rock had experienced Cs and Rb loss prior to Palaeogene times, possibly during a Caledonian event. This depletion caused heterogeneity with respect to 87Sr/86Sr in the crustal source of silicic melts. Other igneous rock types on Rum (dacites, early gabbros) are mixtures of crustalmelts and and primarymantle melts. Forward Rare Earth Element modelling shows that late stage picritic melts on Rum are close analogues for the parent melts of the Rum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss.
These primary mantle melts have close affinities to Mid-Oceanic Ridge Basalts (MORB), whose trace element content varies from slightly depleted to slightly enriched. Crustal anatexis is a common process
in the rift-to-drift evolution during continental break-up and the formation of Volcanic Rifted Margins
systems. The ‘early felsic–later mafic’ volcanic rock associations from Rum are compared to similar
associations recovered from the now-drowned seaward-dipping wedges on the shelf of SE Greenland
and on the Vøring Plateau (Norwegian Sea). These three regions show geochemical differences that
result from variations in the regional crustal composition and the depth at which crustal anatexis took
place
Geological history, chronology and mMagmatic evolution of Merapi
No full textThis chapter provides a synthesis of the geological history, chronology and magmatic evolution of Merapi. Stratigraphic field and geochronological data are used to divide Merapi into three main evolutionary stages and associated volcanic edifices (Proto-, Old and New Merapi) and eight broad volcano-stratigraphic units to characterise the eruptive activity and structural evolution of the volcano through time. Complementary petrological, geochemical and isotopic data are used to characterise the eruptive products of Merapi and shed light on the geochemical evolution and petrogenetic processes. The data indicate that the eruptive products of Merapi are mainly basaltic andesite of both medium-K and high-K type and support a two-stage petrogenetic model, where primary magmas are derived from a heterogenous, Indian Ocean MORB-like mantle source metasomatised by slab-derived components. Subsequently, these magmas are modified during transfer through the crust by complex magmatic differentiation processes, including contamination by carbonate rocks of the local upper crust. The available data indicate that, since ~ 1900 14C y BP, the lavas and pyroclastic rocks of Merapi are essentially of the high-K type and that regular geochemical variations with systematic shifts in whole rock SiO2 content occurred since at least the Late Holocene, although erupted magma compositions have remained broadly uniform since the mid-twentieth century.</p
Recent research developments on the Isle of Rum, NW Scotland
No full textThe appearance in 1997 of the British Geological Survey's memoir on Rum was followed by a period of intense research, leading to upwards of 35 papers, books and other articles. The scope of these publications, and the research progress over the last 15 years since publication of the memoir, is reviewed here. Igneous activity on Rum was short lived, possibly only ca. 500 ka, and, at about 60.5 Ma. The Rum central complex thus pre-dates the nearby Skye central complex. The earliest, acidic and mixed acidic/basic magmatism on Rum involved both shallow intrusions and ignimbrite eruptions into a collapsing caldera bound by the Main Ring Fault, a structure which probably also exercised a structural influence on subsequent mafic and ultrabasic magmatism. Subsequent emplacement of gabbros and ultrabasic rocks caused only limited thermal metamorphism of the surrounding Torridonian sandstones, contrasting markedly with the intense alteration of uplifted masses of Lewisian gneiss within the ring fault. Detailed textural studies on the gabbroic and ultrabasic rocks allow distinction between intrusive peridotites and peridotite that formed as part of the classic layered units of Rum and, furthermore, this work and that on the chromite seams and veins in these rocks shows that movements of trapped magma and magma derived from later intrusions, may produce textures and structures hitherto regarded as primary features of cumulate rocks. Rare picritic dykes provide an indication of likely parent magma for the mafic and ultrabasic rocks, but these and other magmatic rocks on Rum have all undergone varying degrees of crustal contamination, involving both Lewisian granulite and amphibolite crust but, notably, not Moine rocks as at Ardnamurchan. Sulphides in the chromite seams and ultrabasic rocks show possible influences from assimilated Jurassic sediments. From recent apatite fission track studies it seems likely that Rum, in common with other Palaeogene centres, underwent a brief, but significantly younger (Mesozoic) heating event.</p
Sapogenol is a major microbial metabolite in human plasma associated with high protein soy-based diets : the relevance for functional food formulations
No full textFunding: This work was supported by The Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS). Acknowledgments: The authors are grateful to the ALPRO™ Foundation for supporting this work. Author Contributions: Conceptualization, A.M.J. and W.R.R.; methodology, M.N., Y.B., S.H.D., G.J.D., J.S.C.; data curation, M.N.; V.R.; writing—original draft preparation, M.N.; writing—review and editing, M.N.; V.R., W.R.R. All authors have read and agreed to the published version of the manuscript.Peer reviewe
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