Journal: Journal of Volcanology and Geothermal Research

Abbreviation

J. volcanol. geotherm. res.

Publisher

Elsevier

Journal Volumes

ISSN

0377-0273
1872-6097

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Publications 1 - 10 of 69
  • Generation of crystal-poor rhyolites from a shallow plutonic reservoir in the Famatinian arc (Argentina)
    Item type: Journal Article
    Escribano, Facundo A.; Cornet, Julien; Camilletti, Giuliano C.; et al. (2022)
    Journal of Volcanology and Geothermal Research
    The Ordovician rocks of Sierra Las Planchadas are an exceptionally preserved natural example of a plutonic-volcanic connection. Located in northwestern Argentina, the Las Planchadas Formation consists of a monzogranitic batholith that displays a window into the source of large subvolcanic rhyolitic rocks, cryptodomes and volcanic feeder-dykes. Mafic intrusions and felsic dykes occur cutting the plutonic rocks. Grain-scale relationships, whole-rock compositions and mineral chemistry indicate that monzogranites and rhyolites are two comagmatic members which differentiated within upper crust magma reservoirs. Monzogranites accumulated some plagioclase and trapped a large volume of melt, denoted by a high modal percentage (~64–71%) of near-solidus minerals, comprised of alkali feldspar, albite-rich plagioclase (An<30), and late crystallized quartz. The formation of felsic dykes and rhyolitic cryptodomes is the result of a late melt extraction stage facilitated by the injection of hot mafic magmas from deeper in the system. The mafic-induced thermal reactivation increased the amount of melt-filled pore stored within a highly-crystallized monzogranite reservoir. The breakdown of the low-temperature phases overpressurized the mush and opened a network of microfractures into which residual melts, depleted in feldspar-compatible trace elements (Ba, Sr, and Eu), infiltrated. The draining system involved thin interconnected vein-like channels that merged into wider sheet-like conduits. Our results suggest that channelized segregation of late-stage melts in the subvolcanic environment is a mechanism for triggering rhyolitic eruptions.
  • Insights into the dynamics of the Nirano Mud Volcano through seismic characterization of drumbeat signals and V/H analysis
    Item type: Journal Article
    Antunes, Verónica; Planès, Thomas; Obermann, Anne; et al. (2022)
    Journal of Volcanology and Geothermal Research
    Mud volcanoes are rapidly-evolving geological phenomena characterized by the surface expulsion of sediments and fluids from over-pressurized underlying reservoirs. We investigate the Nirano Mud Volcano, Northern Italy, with seismic methods to better understand the dynamic evolution of the system and shed light on its subsurface structure. Our study allowed to detect and characterize three different types of high-frequency drumbeat signals that are present in the most active part of the mud volcano plumbing system. With a back-projection method based on the cross-correlation envelope of signals recorded at different station pairs, we can determine the source location of the drumbeats. These coincide with the location of V/H (vertical-to-horizontal) amplitude peaks obtained from an ambient vibration profile and resistivity anomalies identified in a previous study. We observe that the drumbeats are P-wave dominated signals, with characteristics similar to those found in magmatic settings, i.e. LPs (long-period signals). We suggest that such tremors originate from the migration of mud and gas inside the mud volcanic conduits. The source location, waveform and frequency content of the drumbeats evolve over time. We found that drumbeat occurrence is directly linked with morphological changes at surface.
  • Geochemistry of the Pepom tephra deposits: The most recent intracaldera volcanism of Sete Cidades volcano, São Miguel, Azores
    Item type: Journal Article
    Ellis, Ben S.; Pimentel, Adriano; Wolff, John A.; et al. (2022)
    Journal of Volcanology and Geothermal Research
    Many volcanoes have the ability to impact human infrastructure with explosive activity and understanding the processes of magma generation and conditions of storage in these systems remains a priority. The Sete Cidades volcano on the island of São Miguel, Azores archipelago is exactly such a volcano lying only 12 km from the island's capital city of Ponta Delgada and has been repeatedly active during the Holocene. Sete Cidades is the westernmost central volcano of São Miguel and its most recent explosive volcanism produced the Pepom series of 17 trachytic pumice deposits that were erupted from vents within the caldera. These variably magmatic and phreatomagmatic eruptions involved trachytic magmas that represent the end point of a magmatic evolution dominated by crystal fractionation processes. The magmas contain a mineral assemblage dominated by feldspar, with biotite, clinopyroxene, Fesingle bondTi oxides, amphibole, and trace apatite. Mineral thermometry and hygrometry reveal that the Pepom magmas were stored at temperatures of 789 ± 23 °C to 894 ± 20 °C under volatile-rich conditions (mostly >5 wt% water). Intercalated within the trachytic pyroclastic succession are mafic products that were erupted from vents on the flanks of the volcano suggesting that the evolved, shallow magmatic system may be acting as a barrier to ascending mafic magmas. The Pepom tephra deposits represent trachytic magmas that show limited evidence for the involvement of feldspar-dominated cumulates as has been observed in other settings whereas the preceding, caldera-forming, Santa Bárbara eruption suggests such involvement. Despite the predominant role of fractionation in petrogenesis, the Pepom tephras formed from mildly low-δ18O magmas (4.1 to 5.6‰ for trachyte) and as such require the addition of hydrothermally altered material. The cause of the low-δ18O values remains unknown, but low-δ18O, hydrothermally altered syenitic clasts found within deposits from the nearby Fogo volcano may be potentially analogues.
  • From andesitic volcanism to the formation of a porphyry Cu-Au mineralizing magma chamber
    Item type: Journal Article
    Halter, Werner E.; Bain, Nicolas; Becker, Katja; et al. (2004)
    Journal of Volcanology and Geothermal Research
  • Electrical conductivity, ground displacement, gravity changes, and gas flow at Solfatara crater (Campi Flegrei caldera, Italy): Results from numerical modeling
    Item type: Journal Article
    Rinaldi, Antonio Pio; Todesco, Micol; Vandemeulebrouck, Jean; et al. (2011)
    Journal of Volcanology and Geothermal Research
  • Chemical and isotopic constraints on hydrological processes in Unzen volcanic geothermal system
    Item type: Journal Article
    Yokochi, Reika; Purtschert, Roland; Suda, Yoshimitsu; et al. (2021)
    Journal of Volcanology and Geothermal Research
    Geothermal systems developed in volcanic regions release magmatic volatiles that may forecast volcanic eruptions. These volatiles can be emitted directly in gaseous form to the atmosphere or can be absorbed by condensed geothermal fluid and groundwater that discharges at surface thermal features. The subsurface flow dynamics of these fluids are therefore crucial for the interpretation of their chemical and isotopic compositions. Furthermore, since geothermal fluids are globally used as energy and cultural resources, such information is also important for their sustainable management. In this context, we investigated the subsurface residence times of fluids from three geothermal areas in Shimabara peninsula (Unzen, Shimabara and Obama) by measuring their tritium and 36Cl activities, along with their chemical and stable isotopic compositions. At Shimabara, the trace tritium activities of the geothermal fluids indicate that magmatic volatiles were transported by pre-nuclear (residence time >60 years) groundwaters. Tritium and δD-δ18O data indicate that the steam feeding the Unzen geothermal field is also derived from pre-nuclear meteoric water, and contributing about a quarter of the water budget. The 36Cl/Cl ratio of the geothermal fluids in Obama exceeds that of seawater, indicating subsurface addition of nucleogenic chloride during prolonged water-rock interaction.
  • Linking the Ukinrek 1977 maar-eruption observations to the tephra deposits: New insights into maar depositional processes
    Item type: Journal Article
    Ort, Michael H.; Lefebvre, Nathalie S.; Neal, Christina A.; et al. (2018)
    Journal of Volcanology and Geothermal Research
  • Long-term compositional and eruptive transitions in an early Miocene volcanic system, Central Chile (33°S)
    Item type: Journal Article
    Payacán , Ítalo; Meyer , Martín; Reyes , Javier; et al. (2025)
    Journal of Volcanology and Geothermal Research
    The reconstruction of long-term magmatic and eruptive evolution in arc settings is often limited by the incomplete preservation of volcanic stratigraphy, as sequences in active tectonic regions are commonly disrupted and eroded, making it difficult to link these variations to underlying geodynamic processes. This contribution presents a detailed reconstruction of the prolonged (∼6 Myr) volcanic evolution recorded in a dissected Miocene arc system, based on detailed stratigraphic analysis, whole-rock geochemistry, and U-Pb zircon geochronology. The >2500 m-thick volcanic succession documents diverse eruptive and compositional phases in three stratigraphic units, revealing remarkable changes in magma composition and eruptive style over time. The lower unit is composed of andesitic lavas and pyroclastic breccias, indicating explosive-effusive volcanism prior to 22.6 Ma. Zircon ages from the base of the middle unit confirms the onset of an episode dominated by rhyolitic domes between 22.6 and 18.6 Ma. This is followed by the construction of a composite andesite-basaltic edifice (upper unit), characterized by lava flows and volcanoclastic sequences, with the youngest zircon crystallization ages at ca.15 Ma. The enrichment in incompatible elements in rhyolitic and late andesitic rocks, combined with isotopic evidence for increased crustal assimilation and subducted sediments input within the source, points to a progressive modification of the magmatic system between 22 and 18 Ma. These geochemical and isotopic signatures coincide with the onset of a well-established crustal thickening event in central Chile during this period. This case illustrates how major magmatic changes and eruptive transitions can align with the transition from extensional to contractional tectonics within a single arc segment.
  • Inverting the source mechanism of Strombolian explosions at Mt. Yasur, Vanuatu, using a multi-parameter dataset
    Item type: Journal Article
    Kremers, Simon; Wassermann, Joachim; Meier, Kristina; et al. (2013)
    Journal of Volcanology and Geothermal Research
  • Structure of Masaya and Momotombo volcano, Nicaragua, investigated with a temporary seismic network
    Item type: Journal Article
    Obermann, Anne; Molinari, Irene; Métaxian, Jean-Philippe; et al. (2019)
    Journal of Volcanology and Geothermal Research
Publications 1 - 10 of 69