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Troll, Valentin R.
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Publications (10 of 161) Show all publications
Troll, V. R., Emeleus, C. H., Nicoll, G. R., Mattsson, T., Ellam, R. M., Donaldson, C. H. & Harris, C. (2019). A large explosive silicic eruption in the British Palaeogene Igneous Province. Scientific Reports, 9, Article ID 494.
Open this publication in new window or tab >>A large explosive silicic eruption in the British Palaeogene Igneous Province
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 494Article in journal (Refereed) Published
Abstract [en]

Large-volume pyroclastic eruptions are not known from the basalt-dominated British Palaeogene Igneous Province (BPIP), although silicic magmatism is documented from intra-caldera successions in central volcanoes and from small-volume ash-layers in the associated lava fields. Exceptions are the Sgùrr of Eigg (58.7 Ma) and Òigh-sgeir pitchstones in the Inner Hebrides (>30 km apart), which have been conjectured to represent remnants of a single large silicic event. Currently available major element data from these outcrops differ, however, creating a need to test if the two pitchstones are really related. We employ a systematic array of methods ranging from mineralogy to isotope geochemistry and find that samples from the two outcrops display identical mineral textures and compositions, major- and trace elements, and Sr-Nd-Pb-O isotope ratios, supporting that the two outcrops represent a single, formerly extensive, pyroclastic deposit. Available isotope constraints suggest a vent in the Hebridean Terrane and available radiometric ages point to Skye, ~40 km to the North. A reconstructed eruption volume of ≥5km3 DRE is derived, suggesting a VEI 5 event or larger. We therefore argue, contrary to long-held perception, that large-volume silicic volcanism and its associated climatic effects were likely integral to the BPIP during the opening of the North Atlantic.

National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-366704 (URN)10.1038/s41598-018-35855-w (DOI)000456553400060 ()30679443 (PubMedID)
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-02-12Bibliographically approved
Walter, T. R., Haghighi, M. H., Schneider, F. M., Coppola, D., Motagh, M., Saul, J., . . . Gaebler, P. (2019). Complex hazard cascade culminating in the Anak Krakatau sector collapse. Nature Communications, 10, Article ID 4339.
Open this publication in new window or tab >>Complex hazard cascade culminating in the Anak Krakatau sector collapse
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 4339Article in journal (Refereed) Published
Abstract [en]

Flank instability and sector collapses, which pose major threats, are common on volcanic islands. On 22 Dec 2018, a sector collapse event occurred at Anak Krakatau volcano in the Sunda Strait, triggering a deadly tsunami. Here we use multiparametric ground-based and space-borne data to show that prior to its collapse, the volcano exhibited an elevated state of activity, including precursory thermal anomalies, an increase in the island's surface area, and a gradual seaward motion of its southwestern flank on a dipping decollement. Two minutes after a small earthquake, seismic signals characterize the collapse of the volcano's flank at 13:55 UTC. This sector collapse decapitated the cone-shaped edifice and triggered a tsunami that caused 430 fatalities. We discuss the nature of the precursor processes underpinning the collapse that culminated in a complex hazard cascade with important implications for the early detection of potential flank instability at other volcanoes.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-395724 (URN)10.1038/s41467-019-12284-5 (DOI)000488484200001 ()31575866 (PubMedID)
Funder
EU, Horizon 2020, ERC-CoG 646858
Available from: 2019-10-24 Created: 2019-10-24 Last updated: 2019-10-24Bibliographically approved
Whitley, S., Gertisser, R., Halama, R., Preece, K., Troll, V. R. & Deegan, F. (2019). Crustal CO2 contribution to subduction zone degassing recorded through calc-silicate xenoliths in arc lavas. Scientific Reports, 9, Article ID 8803.
Open this publication in new window or tab >>Crustal CO2 contribution to subduction zone degassing recorded through calc-silicate xenoliths in arc lavas
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 8803Article in journal (Refereed) Published
Abstract [en]

Interaction between magma and crustal carbonate at active arc volcanoes has recently been proposed as a source of atmospheric CO2, in addition to CO2 released from the mantle and subducted oceanic crust. However, quantitative constraints on efficiency and timing of these processes are poorly established. Here, we present the first in situ carbon and oxygen isotope data of texturally distinct calcite in calc-silicate xenoliths from arc volcanics in a case study from Merapi volcano (Indonesia). Textures and C-O isotopic data provide unique evidence for decarbonation, magma-fluid interaction, and the generation of carbonate melts. We report extremely light delta C-13(PDB) values down to -29.3%o which are among the lowest reported in magmatic systems so far. Combined with the general paucity of relict calcite, these extremely low values demonstrate highly efficient remobilisation of crustal CO2 over geologically short timescales of thousands of years or less. This rapid release of large volumes of crustal CO2 may impact global carbon cycling.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-390198 (URN)10.1038/s41598-019-44929-2 (DOI)000472030000036 ()31217464 (PubMedID)
Available from: 2019-08-08 Created: 2019-08-08 Last updated: 2019-08-08Bibliographically approved
Deegan, F. M., Troll, V. R. & Geiger, H. (2019). Forensic Probe of Bali’s Great Volcano. EOS: Transactions, 100(4), 26-30
Open this publication in new window or tab >>Forensic Probe of Bali’s Great Volcano
2019 (English)In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 100, no 4, p. 26-30Article in journal (Refereed) Published
Abstract [en]

In November 2017, the world’s eyes were focused on the tourist island of Bali, Indonesia, as Agung erupted for the first time since 1963 [Gertisser et al., 2018] (Figure 1). Locals refer to Gunung Agung, the Bahasa Indonesian term for “great mountain,” as Bali’s “great volcano.” This latest Balinese eruption and the ensuing ashfall required some 150,000 people to evacuate the area and caused airline flight disruptions and widespread anxiety.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2019
National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-383075 (URN)10.1029/2019EO115211 (DOI)
Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2020-02-14Bibliographically approved
Troll, V. R., Weis, F. A., Jonsson, E., Andersson, U. B., Majidi, S. A., Högdahl, K., . . . Nilsson, K. P. (2019). Global Fe-O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores. Nature Communications, 10, Article ID 1712.
Open this publication in new window or tab >>Global Fe-O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 1712Article in journal (Refereed) Published
Abstract [en]

Kiruna-type apatite-iron-oxide ores are key iron sources for modern industry, yet their origin remains controversial. Diverse ore-forming processes have been discussed, comprising lowtemperature hydrothermal processes versus a high-temperature origin from magma or magmatic fluids. We present an extensive set of new and combined iron and oxygen isotope data from magnetite of Kiruna-type ores from Sweden, Chile and Iran, and compare them with new global reference data from layered intrusions, active volcanic provinces, and established low-temperature and hydrothermal iron ores. We show that approximately 80% of the magnetite from the investigated Kiruna-type ores exhibit d56Fe and d18O ratios that overlap with the volcanic and plutonic reference materials (> 800 degrees C), whereas similar to 20%, mainly vein-hosted and disseminated magnetite, match the low-temperature reference samples (<= 400 degrees C). Thus, Kiruna-type ores are dominantly magmatic in origin, but may contain latestage hydrothermal magnetite populations that can locally overprint primary hightemperature magmatic signatures.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-382552 (URN)10.1038/s41467-019-09244-4 (DOI)000464338100023 ()30979878 (PubMedID)
Funder
Swedish Research Council
Available from: 2019-05-10 Created: 2019-05-10 Last updated: 2019-05-10Bibliographically approved
Heap, M. J., Troll, V. R., Kushnir, A. R. L., Gilg, H. A., Collinson, A. S. D., Deegan, F. M., . . . Walter, T. R. (2019). Hydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour. Nature Communications, 10, Article ID 5063.
Open this publication in new window or tab >>Hydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 5063Article in journal (Refereed) Published
Abstract [en]

Dome-forming volcanoes are among the most hazardous volcanoes on Earth. Magmatic outgassing can be hindered if the permeability of a lava dome is reduced, promoting pore pressure augmentation and explosive behaviour. Laboratory data show that acid-sulphate alteration, common to volcanoes worldwide, can reduce the permeability on the sample lengthscale by up to four orders of magnitude and is the result of pore- and microfracture-filling mineral precipitation. Calculations using these data demonstrate that intense alteration can reduce the equivalent permeability of a dome by two orders of magnitude, which we show using numerical modelling to be sufficient to increase pore pressure. The fragmentation criterion shows that the predicted pore pressure increase is capable of fragmenting the majority of dome-forming materials, thus promoting explosive volcanism. It is crucial that hydrothermal alteration, which develops over months to years, is monitored at dome-forming volcanoes and is incorporated into real-time hazard assessments.

National Category
Geology
Identifiers
urn:nbn:se:uu:diva-397637 (URN)10.1038/s41467-019-13102-8 (DOI)000494938500001 ()31700076 (PubMedID)
Funder
EU, Horizon 2020
Available from: 2019-11-22 Created: 2019-11-22 Last updated: 2019-11-22Bibliographically approved
Sun, W., Yuan, F., Jowitt, S. M., Zhou, T., Liu, G., Li, X., . . . Troll, V. R. (2019). In situ LA-ICP-MS trace element analyses of magnetite: genetic implications for the Zhonggu orefield, Ningwu volcanic basin, Anhui Province, China. Mineralium Deposita, 54(8), 1243-1264
Open this publication in new window or tab >>In situ LA-ICP-MS trace element analyses of magnetite: genetic implications for the Zhonggu orefield, Ningwu volcanic basin, Anhui Province, China
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2019 (English)In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 54, no 8, p. 1243-1264Article in journal (Refereed) Published
Abstract [en]

The Zhonggu orefield is located within the southern Ningwu volcanic basin and is one of the largest iron ore districts within the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB) of eastern China. The area hosts the Gushan iron oxide-apatite (IOA) deposit and the Baixiangshan, Longshan, Hemushan, Zhongjiu, and Taipingshan skarn-type iron deposits. Here, we employ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to determine trace element concentrations in magnetite from these deposits. Combining these new data with geological information from these deposits indicates that the iron ore within the Gushan deposit has V and Ti compositions that are strongly suggestive of a Kiruna-type IOA origin. Specifically, the V and Ti chemistry of magnetite in iron ore breccias from the Gushan deposit suggests that this style of mineralization formed at a high temperature and as a result of magmatic magnetite precipitation. This was followed by precipitation of lower temperature magmatic-hydrothermal massive magnetite. Both types of magnetite host exsolved ilmenite. Elemental mapping also indicates that Gushan breccia-hosted magnetite records hydrothermal fluid activity that formed late-stage vein mineralization. In comparison, other deposits within the Zhonggu orefield all contain magnetite with compositions that are indicative of skarn mineralization. This implies that these deposits formed as a result of magmatic-hydrothermal rather than purely magmatic or purely hydrothermal activity, contrasting with the Gushan deposit. Finally, the geochemistry of magnetite within thick anhydrite units in the Longshan deposit indicates the formation by low-temperature sedimentary processes, and this magnetite was subsequently overprinted as a result of hydrothermal activity during the formation of the main Longshan deposit. Overall, this study indicates that the IOA, skarn-type, and sedimentary anhydrite-type iron mineralization in the Zhonggu iron ore field record evolving metallogenic processes from initially orthomagmatic mineralizing systems to high- to moderate-temperature magmatic-hydrothermal systems and finally to low-temperature hydrothermal mineralization.

Place, publisher, year, edition, pages
SPRINGER, 2019
Keywords
Zhonggu orefield, LA-ICP-MS, Trace elements, Kiruna, Iron oxide-apatite, Skarn
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-397796 (URN)10.1007/s00126-019-00872-w (DOI)000493612600008 ()
Available from: 2019-11-27 Created: 2019-11-27 Last updated: 2019-11-27Bibliographically approved
Sahlström, F., Jonsson, E., Högdahl, K., Troll, V. R., Harris, C., Jolis, E. M. & Weis, F. (2019). Interaction between high-temperature magmatic fluids and limestone explains 'Bastnäs-type' REE deposits in central Sweden. Scientific Reports, 9, Article ID 15203.
Open this publication in new window or tab >>Interaction between high-temperature magmatic fluids and limestone explains 'Bastnäs-type' REE deposits in central Sweden
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 15203Article in journal (Refereed) Published
Abstract [en]

The presently increasing demand for rare earth elements (REE), particularly in high-tech and "green energy" applications, has led to global interest in the distribution, origins and formation conditions of REE deposits. The World's first hard-rock REE sources, the polymetallic deposits of Bastnasfaltet in Bergslagen, central Sweden, were also the place of the original discovery of several REE and many of their host minerals. Similar deposits with high concentrations of REE occur along a >100 km corridor in the region and they share a number of geological and mineralogical features; all comprising Palaeoproterozoic, skarn-hosted magnetite-REE mineralisation of ambiguous origin. Here we report oxygen isotope data for magnetite and quartz, and oxygen and carbon isotope data for carbonates from ten of these classic deposits, to model and assess their mode of origin. Combined with existing geological observations, the isotope results support an origin in a c. 1.9 Ga shallow-marine back-arc, sub-seafloor setting, where felsic magmatic-sourced, high-temperature fluids reacted with pre-existing limestone interlayers, leading to localised skarn formation and magnetite-REE-mineral precipitation. These findings help us to better understand the geological processes that have produced economic REE mineralisation and may assist future exploration for these critical commodities.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-399091 (URN)10.1038/s41598-019-49321-8 (DOI)000491859400008 ()31645579 (PubMedID)
Funder
Swedish Research CouncilThe Geological Survey of Sweden (SGU)
Available from: 2019-12-16 Created: 2019-12-16 Last updated: 2019-12-16Bibliographically approved
Troll, V. R., Rodriguez-Gonzalez, A., Deegan, F., Perez-Torrado, F. J., Carracedo, J. C., Thomaidis, K., . . . Meade, F. C. (2019). Sacred ground; the Maipés necropolis of north-west Gran Canaria: the Maipés necropolis of north-west Gran Canaria. Geology Today, 35(2), 55-62
Open this publication in new window or tab >>Sacred ground; the Maipés necropolis of north-west Gran Canaria: the Maipés necropolis of north-west Gran Canaria
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2019 (English)In: Geology Today, Vol. 35, no 2, p. 55-62Article in journal (Refereed) Published
Abstract [en]

Gran Canaria, like most of the Canary Islands, shows evidence for young basaltic volcanism in the form of cinder cones and valley-hugging lava flows. These landforms were of no particular use to the aboriginal population, nor to the subsequent Spanish settlers, and young lava flows and lava fields are still referred to as ‘malpaís’ (badlands) in the Canary Islands. In north-west Gran Canaria, one such lava flow fills the bottom of a steep-sided valley, which reaches the sea at the present day village of Agaete. The lava flow erupted c. 3030 ± 90 yr bp and displays a total length of ∌ 11 km. At its distal end, just outside Agaete, it hosts one of Europe’s largest and most important pre-historic burial sites constructed of volcanic rock: the Maipés necropolis. Over 700 pre-historic tombs (or tumuli) constructed from the aa-type clinker materials have been identified on top of the valley-filling lava flow. The up to soccer-ball sized vesicular clinker fragments are sufficiently low in density to provide abundant, workable basalt blocks for the construction of the tumuli, allowing the pre-hispanic aboriginal population to create a large and magnificent ‘sacred ground’ in an otherwise barren landscape.

National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-383080 (URN)10.1111/gto.12262 (DOI)
Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2020-02-20Bibliographically approved
Gonzalez-Maurel, O., le Roux, P., Godoy, B., Troll, V. R., Deegan, F. & Menzies, A. (2019). The great escape: Petrogenesis of low-silica volcanism of Pliocene to Quaternary age associated with the Altiplano-Puna Volcanic Complex of northern Chile (21 degrees 10 '-22 degrees 50 ' S). Lithos, 346/347, Article ID UNSP 105162.
Open this publication in new window or tab >>The great escape: Petrogenesis of low-silica volcanism of Pliocene to Quaternary age associated with the Altiplano-Puna Volcanic Complex of northern Chile (21 degrees 10 '-22 degrees 50 ' S)
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2019 (English)In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 346/347, article id UNSP 105162Article in journal (Refereed) Published
Abstract [en]

The Pliocene to Quaternary volcanic arc of the Central Andes formed on 70-74 km thick continental crust. Physical interaction between mafic and acid magmas for this arc are therefore difficult to recognize due to the differentiation of mantle-derived magma during ascent through the thickened crust and a corresponding lack of erupted primitive lavas. However, a rare concentration of less evolved rocks is located marginal to the partially molten Altiplano-Puna Magma Body (APMB) in the Altiplano-Puna Volcanic Complex of northern Chile, between 21 degrees 10'S and 22 degrees 50'S. To unravel the relationship between this less evolved magmatism and the APMB, we present major and trace element data, and Sr and Nd isotope ratios of fourteen volcanoes. Whole-rock compositional and Sr and Nd isotope data reveal a large degree for compositional heterogeneity, e.g., SiO2 = 53.2 to 63.2 wt%, MgO = 1.74 to 6.08 wt%, Cr = 2 to 382 ppm, Sr = 304 to 885 ppm, (87)sr/(86)sr = 0.7055 to 0.7088, and Nd-143/Nd-144 = 0.5122 to 0.5125. The combined dataset points to magma spatial compositional changes resulting from magma mixing, fractional crystallization and crustal assimilation. The least evolved products erupted along the periphery of the APMB and are likely equivalent to the replenishing magmas that thermally sustain the large APMB system. We suggest that the mafic to intermediate eruptives we have investigated reflect mafic melt injections that underplate the APMB and escape along the side of the large felsic body to avoid significant compositional modifications during ascent, which helps to assess the evolution of the APMB through space and time. (C) 2019 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER, 2019
Keywords
Low-silica volcanism, Altiplano-Puna Volcanic Complex, Altiplano-Puna Magma Body, Sr and Nd radiogenic isotopes
National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-395713 (URN)10.1016/j.lithos.2019.105162 (DOI)000488335600019 ()
Funder
Swedish Research Council
Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
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