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Budd, David A.
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Budd, David A.
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- PublicationRestrictedTraversing nature’s danger zone: getting up close with Sumatra’s volcanoes.(2012)
; ; ; ; ; ; ;Budd, D. A.; Department of Earth Sciences, Uppsala University, Uppsala, Sweden ;Troll, V. R.; Department of Earth Sciences, Uppsala University, Uppsala, Sweden ;Hilton, D. R.; Scripps Institution of Oceanography, University of California San Diego, California, USA ;Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Jolis, E. M.; Department of Earth Sciences, Uppsala University, Uppsala, Sweden ;Halldorsson, S. A.; Scripps Institution of Oceanography, University of California San Diego, California, USA; ; ; ; ; The Indonesian island of Sumatra, located in one of the most active zones of the Pacific Ring of Fire, is characterized by a chain of subduction-zone volcanoes which extend the entire length of the island. As a group of volcanic geochemists, we embarked upon a five-week sampling expedition to these exotic, remote, and in part explosive volcanoes (SAGE 2010; Sumatran Arc Geochemical Expedition). We set out to collect rock and gas samples from 17 volcanic centres from the Sumatran segment of the Sunda arc system, with the aim of obtaining a regionally significant sample set that will allow quantification of the respective roles of mantle versus crustal sources to magma genesis along the strike of the arc. Here we document our geological journey through Sumatra’s unpredictable terrain, including the many challenges faced when working on active volcanoes in pristine tropical climes.227 16 - PublicationOpen AccessMagma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz(2017-01)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ;Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum Δcore−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.481 80 - PublicationOpen AccessFloating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption(2012)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Troll, V. R.; Dept. of Earth Sciences, Uppsala University, Sweden ;Klugel, A.; nstitute of Geosciences, University of Bremen, Germany ;Longpre, M. -A.; Dept. of Earth and Planetary Sciences, McGill University, Canada ;Burchardt, S.; Dept. of Earth Sciences, Uppsala University, Sweden ;Deegan, F. M.; Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockholm, Sweden ;Carracedo, J. C.; Dept. of Physics (Geology), GEOVOL, University of Las Palmas, Gran Canaria, Spain ;Wiesmaier, S.; Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universit¨at, Munich, Germany ;Kueppers, U.; Dept. of Earth and Environmental Sciences, Ludwig-Maximilians Universit¨at, Munich, Germany ;Dahern, B.; Dept. of Earth Sciences, Uppsala University, Sweden ;Hansteen, T. H.; Leibniz-Institute for Oceanography, IFM-GEOMAR, Kiel, Germany ;Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Budd, D.; Dept. of Earth Sciences, Uppsala University, Sweden ;Jolis, E. M.; Dept. of Earth Sciences, Uppsala University, Sweden ;Polacci, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; ; ; ; ; ; ; ; ; ; ; ; ; A submarine eruption started off the south coast of El Hierro, Canary Islands, on 10 October 2011 and continues at the time of this writing (February 2012). In the first days of the event, peculiar eruption products were found floating on the sea surface, drifting for long distances from the eruption site. These specimens, which have in the meantime been termed “restingolites” (after the close-by village of La Restinga), appeared as black volcanic “bombs” that exhibit cores of white and porous pumice-like material. Since their brief appearance, the nature and origin of these “floating stones” has been vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The “restingolites” have been proposed to be either (i) juvenile high-silica magma (e.g. rhyolite), (ii) remelted magmatic material (trachyte),(iii) altered volcanic rock, or (iv) reheated hyaloclastites or zeolite from the submarine slopes of El Hierro. Here, we provide evidence that supports yet a different conclusion. We have analysed the textures and compositions of representative “restingolites” and compared the results to previous work on similar rocks found in the Canary Islands. Based on their high-silica content, the lack of igneous trace element signatures, the presence of remnant quartz crystals, jasper fragments and carbonate as well as wollastonite (derived from thermal overprint of carbonate) and their relatively high oxygen isotope values, we conclude that “restingolites” are in fact xenoliths from pre-island sedimentary layers that were picked up and heated by the ascending magma, causing them to partially melt and vesiculate. As they are closely resem- bling pumice in appearance, but are xenolithic in origin, we refer to these rocks as “xeno-pumice”. The El Hierro xeno- pumices hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies beneath the Canary Islands as well as in similar Atlantic islands that rest on sediment-covered ocean crust (e.g. Cape Verdes, Azores). The occurrence of “restingolites” indicates that crustal recycling is a relevant process in ocean islands, too, but does not herald the arrival of potentially explosive high-silica magma in the active plumbing system beneath El Hierro. results of our textural, mineralogical, elemental and isotopic analysis lead us to conclude that the early floating stones of El Hierro are vesiculated crustal xenoliths that originate from the substantial layer of sub-volcanic pre-island sedimentary rocks (layer 1 of the oceanic crust) that is present underneath the Canary archipelago.554 201