40 Result(s)
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Valentin R. Troll
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Open AccessReported ultra-low lava viscosities from the 2021 La Palma eruption are potentially biased
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Open AccessWater in clinopyroxene from the 2021 Geldingadalir eruption of the Fagradalsfjall Fires, SW-Iceland
Water content plays a significant role in magma genesis, ascent rate, and, ultimately, in the style and intensity of volcanic eruptions, due to its control on the density, viscosity and melting behaviour of si...
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Open AccessIron isotopes constrain sub-seafloor hydrothermal processes at the Trans-Atlantic Geotraverse (TAG) active sulfide mound
Sub-seafloor hydrothermal processes along volcanically active plate boundaries are integral to the formation of seafloor massive sulfide deposits and to oceanic iron cycling, yet the nature of their relationsh...
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Whole-rock oxygen isotope ratios as a proxy for the strength and stiffness of hydrothermally altered volcanic rocks
Hydrothermal alteration is considered to increase the likelihood of dome or flank collapse by compromising stability. Understanding how such alteration influences rock properties, and providing independent met...
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Open AccessAbsence of hydrothermal oxygen isotope variations in host rocks supports magmatic origin of the giant Grängesberg iron oxide–apatite (IOA) deposit, Central Sweden
The origin of Kiruna-type iron oxide–apatite ores is controversial, and debate presently centres on a ‘magmatic’ versus a ‘hydrothermal’ mode of formation. To complement recent investigations on the Grängesber...
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Open AccessHidden mechanical weaknesses within lava domes provided by buried high-porosity hydrothermal alteration zones
Catastrophic lava dome collapse is considered an unpredictable volcanic hazard because the physical properties, stress conditions, and internal structure of lava domes are not well understood and can change ra...
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Open AccessSunda arc mantle source δ18O value revealed by intracrystal isotope analysis
Magma plumbing systems underlying subduction zone volcanoes extend from the mantle through the overlying crust and facilitate protracted fractional crystallisation, assimilation, and mixing, which frequently o...
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Open AccessPetrogenesis of the Loch Bà ring-dyke and Centre 3 granites, Isle of Mull, Scotland
The Loch Bà ring-dyke and the associated Centre 3 granites represent the main events of the final phase of activity at the Palaeogene Mull igneous complex. The Loch Bà ring-dyke is one of the best exposed ring...
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Employing geochemistry and geochronology to unravel genesis and tectonic setting of iron oxide-apatite deposits of the Bafq-Saghand metallogenic belt, Central Iran
The Bafq-Saghand metallogenic belt is located in the central part of the Kerman–Kashmar tectonic zone and contains 39 individual occurrences of iron oxide-apatite ± REE mineralizations. These mineral concentra...
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Open AccessConstraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile
The Andean continental arc is built upon the thickest crust on Earth, whose eruption products reflect varying degrees of crustal assimilation. In order to robustly model magma evolution and assimilation at sub...
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Open AccessHydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour
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 beh...
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In situ LA–ICP–MS trace element analyses of magnetite: genetic implications for the Zhonggu orefield, Ningwu volcanic basin, Anhui Province, China
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 are...
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Open AccessInteraction between high-temperature magmatic fluids and limestone explains ‘Bastnäs-type’ REE deposits in central Sweden
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...
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Open AccessComplex hazard cascade culminating in the Anak Krakatau sector collapse
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 dea...
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Open AccessCrustal CO2 contribution to subduction zone degassing recorded through calc-silicate xenoliths in arc lavas
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,...
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Open AccessGlobal Fe–O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores
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 low-temperature hydrothermal ...
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Open AccessA large explosive silicic eruption in the British Palaeogene Igneous Province
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 volcano...
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Open AccessMulti-level magma plumbing at Agung and Batur volcanoes increases risk of hazardous eruptions
The island of Bali in Indonesia is home to two active stratovolcanoes, Agung and Batur, but relatively little is known of their underlying magma plumbing systems. Here we define magma storage depths and isotop...
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Amphibole megacrysts as a probe into the deep plumbing system of Merapi volcano, Central Java, Indonesia
Amphibole has been discussed to potentially represent an important phase during early chemical evolution of arc magmas, but is not commonly observed in eruptive arc rocks. Here, we present an in-depth study of...
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Open AccessMagma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz
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...
