Journal of Volcanology and Geothermal Research最新文献

{"title":"Geothermal gas geochemistry in Southeast Tibetan Plateau margin influenced by magma chambers and fractures","authors":"Jia-Yi Wu ,&nbsp;Hai Gang Cao ,&nbsp;Peng Cheng Zhao ,&nbsp;Yu Ping Guo ,&nbsp;Xue-Gang Chen ,&nbsp;Xiaohu Li ,&nbsp;Jui-Fen Tsai ,&nbsp;Pei-Ling Wang ,&nbsp;Li-Hung Lin","doi":"10.1016/j.jvolgeores.2025.108323","DOIUrl":"10.1016/j.jvolgeores.2025.108323","url":null,"abstract":"<div><div>Hydrothermal gases play a pivotal role in elucidating the cycling of deep materials and subsurface processes. Here, we analyzed the chemical and isotopic compositions of 40 gas samples and compiled geochemical data on &gt;280 samples discharged from the Tengchong hydrothermal field, located on the Southeast Tibetan Plateau margin. Helium isotopes span from 0.13 <em>R</em>_<em>a</em> (the ³He/⁴He ratio of air) to 5.91 <em>R</em>_<em>a</em>, indicating a mixing between mantle-derived helium and crustal components. Spatial distributions of helium isotopes are closely associated with the locations of magma chambers beneath the Tengchong field. N₂/Ar ratios and nitrogen isotopic compositions suggest that N₂ and Ar were primarily contributed by atmospheric sources and groundwater, with minor N₂ contributions from mantle-derived materials. CO₂ was mostly originated from the thermal decomposition of limestone and magma degassing, with a few samples affected by secondary processes like carbonate precipitation. The chemical and carbon‑hydrogen isotopic compositions of alkanes indicate that methane was mainly sourced from thermogenic processes. The central magma chamber and its adjacent faults are characterized by the most intensive magmatic activity and the closest connection to deep materials. A gas migration and diffusion model using a crustal ³He endmember of 6 × 10⁻⁹–9 × 10⁻⁸ (volume ratio of ³He to total gases) well explains the decreasing ³He concentrations with the distance from magma chambers. Hence, the highly penetrable helium in quiescent regions like Tengchong could migrate through overlying rocks without the need of gas channeling along faults. Similarly, our model can also explain the relationships between Ar concentrations and the distance from springs to faults and magma chambers. In contrast, the geochemical characteristics of other gas components (e.g., CO₂, N₂) are closely associated with the location of major faults. This study offers valuable insights into the spatial relationships between gas geochemistry and subsurface magmatism and fault distribution, highlighting the influence of hydrothermal processes on diverse patterns of gas migration and source in hydrothermal fields.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108323"},"PeriodicalIF":2.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclical dome formation and destruction leading to highly explosive PDCs at the Late Pleistocene Tlaloc volcano, Mexico","authors":"Mario Emmanuel Boijseauneau-López ,&nbsp;Giovanni Sosa-Ceballos ,&nbsp;Xavier Bolós ,&nbsp;José Luis Macías","doi":"10.1016/j.jvolgeores.2025.108326","DOIUrl":"10.1016/j.jvolgeores.2025.108326","url":null,"abstract":"<div><div>The age, eruptive dynamics, and magmatic processes driving the explosive eruptions of the Tlaloc stratovolcano remain poorly understood. These eruptions may reflect a cyclical phase of dome growth and destruction, as suggested by lithic content variations within the Late Pleistocene units of Tlaloc. In this study, we present stratigraphic, petrological, and compositional analyses of three major units: Xichimanla (unknown age), La Joya (between 38 and 43.5 ka), and Tlaminca (∼34 ka). These units, consisting of pyroclastic density current (PDC) deposits emplaced along the NW gullies of the volcano, capture a significant part of its explosive eruptive history during the Late Pleistocene. The Xichimanla, La Joya, and Tlaminca units represent vent-opening events initiated by dome explosions, followed by boil-over-type eruptions. A distinct compositional transition from rhyodacite to rhyolite (64.16–69.25 wt% SiO₂) is evident in the units. Textural and geochemical evidence, including banded pumice, disequilibrium textures in plagioclase, amphibole, and pyroxene, as well as the presence of xenoliths, xenocrystals and mineral relics, suggest that the explosive eruptions at Tlaloc were driven by magma mixing and crustal assimilation. The interaction between a mafic recharge magma and a resident felsic reservoir generated a hybridized melt, incorporating remobilized crystal mush parts from felsic reservoirs. These processes, along with volatile input from crustal assimilation, contributed to overpressure buildup and ultimately triggered explosive activity. Amphibole thermobarometry (100–500 MPa) from the La Joya PDC points to the presence of multiple magma reservoirs beneath Tlaloc, potentially explaining the compositional and textural variability. Moreover, the shift from effusive to explosive behavior may have been triggered by the intrusion of fresh, hot magmas into deeper reservoirs, introducing volatiles and heat that facilitated melt migration toward shallower chambers before eruption. These processes could explain the explosive eruptive dynamics of other stratovolcanoes in the Sierra Nevada of Mexico.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108326"},"PeriodicalIF":2.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogeochemical processes governing the origin, mobility and transport of trace elements in the Domuyo Volcanic complex Geothermal system (Patagonia, Argentina)","authors":"Joaquin Llano ,&nbsp;Lorenza Li Vigni ,&nbsp;Mariano Agusto ,&nbsp;Lorenzo Brusca ,&nbsp;Alberto Caselli ,&nbsp;Giovanni Chiodini ,&nbsp;Walter D'Alessandro ,&nbsp;Matteo Lelli ,&nbsp;Franco Tassi ,&nbsp;Orlando Vaselli ,&nbsp;Sergio Calabrese","doi":"10.1016/j.jvolgeores.2025.108322","DOIUrl":"10.1016/j.jvolgeores.2025.108322","url":null,"abstract":"<div><div>The system of Domuyo Volcanic Complex is one of the most promising geothermal fields of Patagonia (Argentina). In this paper, we present a geochemical model of the Domuyo geothermal system based on previous studies and integrated with the systematic characterization of trace elements, thus adding a new piece to the puzzle of one of the most impressive geothermal systems in Argentina.. A total of 38 water samples were collected from 17 different sampling sites, during three field-campaigns from 2013 to 2016, and analysed for 28 trace elements (Li, Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Zr, Mo, Cd, Sb, Cs, Ba, Tl, Pb, Th and U). Sampling sites included the main river (Varvarco), its tributaries which cross the geothermal area, and thermal and cold springs. The investigation was focused on the origin, behaviour and estimation of mass fluxes of trace elements. Computing mass fluxes of trace elements transported by rivers is an important tool in the estimation of both the impact of potentially toxic elements and the exploitation of economically valuable elements. Among others, the mass fluxes of trace elements originating from the Domuyo geothermal system transported by rivers range from 45 to 278 t y⁻¹ for As, B, Cs, Li, Sr and Rb; such contributions flow to the Varvarco river, where the concentrations and mass fluxes of these elements increase by one to two orders of magnitude in the site downstream of the geothermal area with respect to that upstream.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108322"},"PeriodicalIF":2.4,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applying U–Th disequilibrium for dating siliceous sinters","authors":"L. Sankovitch ,&nbsp;C. Munoz-Saez ,&nbsp;A.M. Hudson ,&nbsp;L. Godfrey ,&nbsp;J.M. Thompson","doi":"10.1016/j.jvolgeores.2025.108324","DOIUrl":"10.1016/j.jvolgeores.2025.108324","url":null,"abstract":"<div><div>Continental hydrothermal systems are critical avenues for the crustal transport of heat and mass captured for geothermal energy and mineral exploration. Thus, understanding their temporal evolution and longevity is important for resource characterization. Deposits of microlaminated siliceous sinter, common surface expressions of high temperature reservoirs (&gt; 170 °C), have the potential to trace hydrothermal histories. Geothermal reservoirs are often located within uranium-bearing silicic volcanic rock where subsurface fluid-rock interactions extract U into hydrothermal fluids. U incorporated in the surface sinter deposit has the potential to provide a U–Th disequilibrium dating option. We focus on samples from El Tatio geyser field in the Altiplano of northern Chile, the largest geothermal system in the Andes. Our resulting ²³⁰Th/U ages, along with the water and deposit elemental compositions, suggest concentrations of U and Th vary predictably along the sinter apron. While distal facies containing the highest U concentrations (&gt; 50 μg/g) are least affected by detrital Th corrections, they can display suspected open-system behavior. In contrast, more medial facies, where bacterial mats and other porous textures are commonly concentrated, have only trace amounts of U (&lt; 0.1 μg/g), which leads to unreliable or geologically improbable dates. Proximal facies tend to date most consistently. By comparing existing ¹⁴C ages with ²³⁰Th/U results, ²³⁰Th/U ages tend to be younger than the ¹⁴C ages, supporting the presence of a ¹⁴C-dead carbon influence. New data confirm that the onset of geothermal activity at El Tatio goes back to the late Pleistocene.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108324"},"PeriodicalIF":2.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Volcanic gas changes prior to Stromboli's major explosions are statistically significant","authors":"Alessandro Aiuppa ,&nbsp;Marcello Bitetto ,&nbsp;Luciano Curcio ,&nbsp;Dario Delle Donne ,&nbsp;João Lages ,&nbsp;Giovanni Lo Bue Trisciuzzi ,&nbsp;Giancarlo Tamburello ,&nbsp;Angelo Vitale ,&nbsp;Flavio Cannavò ,&nbsp;Mauro Coltelli ,&nbsp;Diego Coppola ,&nbsp;Lorenzo Innocenti ,&nbsp;Laura Insinga ,&nbsp;Giorgio Lacanna ,&nbsp;Marco Laiolo ,&nbsp;Francesco Massimetti ,&nbsp;Marco Pistolesi ,&nbsp;Eugenio Privitera ,&nbsp;Maurizio Ripepe ,&nbsp;Marija Voloschina ,&nbsp;Giovanna Cilluffo","doi":"10.1016/j.jvolgeores.2025.108325","DOIUrl":"10.1016/j.jvolgeores.2025.108325","url":null,"abstract":"<div><div>The generally mild activity of mafic, open-vent volcanoes is punctuated by the periodic occurrence of sudden, larger-than-normal explosive eruptions. Examples of these sudden mafic explosive events are the so-called “major explosions” that occur (2 to 4 times a year on average) at Stromboli volcano in Italy. These relatively small explosions (Volcanic Explosivity Index, VEI &lt; 1) occur without no obvious precursory change in surface activity, and therefore pose a threat to volcanologists/monitoring staff, and to the population in the most severe cases. Past work has found a link between periods of high CO₂/SO₂ ratios in the volcanic gas plume and the occurrence of such explosions, but this association has never been statistically verified. Here, we report on nearly continuous observations of volcanic gas plume CO₂ and SO₂ concentrations and ratios in a diluted plume, as well as SO₂ flux measurements, recorded in a four year (2020 to 2023) activity period of Stromboli volcano, during which 22 such major explosions took place. Using the Conditional Logit model and the Receiver Operating Characteristic (ROC) analysis, we establish a statistical association between the occurrence of major explosions and periods of reduced SO₂ concentrations (very significant) and fluxes, and high CO₂/SO₂ ratios (significant), in the volcanic plume. These findings are interpreted in light of a simplified conceptual model that explains major explosions as caused by gas bubble accumulation at a rheological discontinuity, resulting from deceleration of the shallow convecting magma that supplies the “regular” Strombolian activity. Using results of statistical analysis, we develop a volcanic gas-based Composite indicator that successfully forecasts (by a-posteriori analysis) 71 % of the events on timescales of week(s). However, we find that this Composite indicator is associated with a large (32 %) False Positive rate and hence low precision (20 %). The significant role of SO₂ concentrations in the model indicates that other factors, such as plume direction and inter-crater variations in gas composition, may need to be taken into account for improving the forecasting performance of the method. Thus, while our results emphasize the importance of gas plume observations in volcano monitoring, they also highlight their current limitations as eruption forecasting tools.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108325"},"PeriodicalIF":2.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detecting explosive volcanism using global long-range infrasound data","authors":"Duccio Gheri ,&nbsp;Emanuele Marchetti ,&nbsp;Rodrigo De Negri ,&nbsp;Patrick Hupe ,&nbsp;Giacomo Belli ,&nbsp;Alexis Le Pichon ,&nbsp;Sven Peter Näsholm ,&nbsp;Pierrick Mialle","doi":"10.1016/j.jvolgeores.2025.108320","DOIUrl":"10.1016/j.jvolgeores.2025.108320","url":null,"abstract":"<div><div>Volcanoes have the potential to erupt abruptly, ejecting ash into the atmosphere and posing risks, among others, to civil aviation. Such explosive eruptions often occur unnoticed, complicating the air traffic management efforts of Volcanic Ash Advisory Centres (VAACs) of the International Civil Aviation Organization. Explosive eruptions are efficient sources of infrasound that, thanks to the low attenuation in the atmosphere, allow volcano monitoring at long (up to &gt;1000 km) distances. The Volcanic Information System (VIS) is a recent framework for detecting eruptive events in near real-time (considering the slow propagation of infrasound), based on infrasound observations from one or several arrays of infrasound sensors. Several studies have already proved the efficiency of long-range infrasound monitoring and VIS in particular, but a systematic and global validation has not yet been done. In the current study, we investigate the reliability of VIS based on 10 years (2010–2019) of data provided by 16 infrasound arrays of the International Monitoring System operated by the Comprehensive Nuclear-Test-Ban Treaty Organization. The dataset contains eruptions with a Volcanic Explosivity Index (VEI) of 2 (mild explosions) to 4 (very energetic explosions with a high ash column). In order to estimate the rate of false positives, VIS records are compared with reports from the Global Volcanism Program. Our results show that VIS is well designed for large (VEI <span><math><mo>≥</mo><mn>3</mn></math></span>) and long-lasting (Sub-Plinian/Plinian) events, as well as for highly repeated Vulcanian/Strombolian explosions. On the other hand, it typically misses single explosive, transient (few seconds) eruptive events. Good results on true detected events are obtained within 1000 km and up to 2000 km range under downwind propagation conditions. Unresolved ambiguity often remains for cases with small angular separation between volcanoes with respect to the infrasound array. We tackle the issue of azimuth resolution by considering volcanic sectors rather than single edifices. This approach can still provide critical information to the VAACs for triggering independent and extended analysis on ongoing volcanic eruptions.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108320"},"PeriodicalIF":2.4,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microlitic crystal-venting episodes at two trachytic lava domes of the Chaîne des Puys (France): Description, experiments and modelling.","authors":"Miallier Didier ,&nbsp;Boivin Pierre ,&nbsp;Arbaret Laurent ,&nbsp;Burgisser Alain ,&nbsp;Deniel Catherine","doi":"10.1016/j.jvolgeores.2025.108319","DOIUrl":"10.1016/j.jvolgeores.2025.108319","url":null,"abstract":"<div><div>We document and propose plausible explanations of microlite-rich pyroclastic density currents (PDCs) that ended the main effusive phases of two highly porous trachytic domes: the Puy de Dôme and Grand Sarcoui (Quaternary volcanic field of the Chaîne des Puys, France). At both volcanoes, these PDCs are evidenced by thick, unique pyroclastic deposits that originated from a late summit, open-vent eruption. These deposits are mainly composed of microlitic feldspar laths that are either free or weakly cohesive with some traces of glass. We present HP-HT crystallization experiments to constrain the pre-eruptive conditions. In these experiments, the initial water content of the material is a crucial parameter since the trachytic domes of the Chaîne des Puys exhibit the highest pre-eruptive H2O contents ever reported for alkaline liquids in an intraplate continental context. Our observations and textural and experimental results lead us to propose three models able to explain the occurrence of a microlite suspension at depth after the initial construction of a dome. Model 1 and Model 2 explore the scenario of gas accumulation within the conduit, or at the upper part of the reservoir; Model 3 explores the scenario of gas accumulation below a shallow impermeable plug. Whereas the highly porous nature of the trachyte must have favored gas escape preventing any explosivity of the dome itself during its early growth, the late explosive phase that generated the crystal-rich PDC points to an excess pressure due to drastic porosity reduction of the trachyte above the accumulated mush. We expect that it is the result of the combination of void collapse caused by depressurization and nearly complete outgassing, and pervasive silicification leading to an impermeable carapace. The results of both Models 1 and 2 call for a sector collapse that causes the final pressure drop and conduit evacuation. Since sector collapses at domes are common, the rarity of such microlitic ash deposits could partly be explained by the low viscosity that characterizes these uncommon trachytic melts. Model 3 results suggest that a specific thickness of sealed magma could be the feeding conduit, or alternatively a lateral shallow intrusion of magma of specific dimensions that accumulates gas below an impermeable cap, which can be either roof rocks or cristobalite precipitation within the upper part of the sill. The available data do not allow us to favor any of the models — or a combination thereof if we do not suppose a unique mechanism operating at both volcanoes.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108319"},"PeriodicalIF":2.4,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magmatic evolution of basaltic rear-arc monogenetic volcanism in southern Colombia","authors":"Ana Toro ,&nbsp;Hugo Murcia ,&nbsp;Laura Sánchez-Torres","doi":"10.1016/j.jvolgeores.2025.108312","DOIUrl":"10.1016/j.jvolgeores.2025.108312","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Guamuez-Sibundoy Monogenetic Volcanic Field is located in the Southern Volcanic Segment of the Central Cordillera of Colombia. The field hosts 19 volcanoes, including scoria cones, maars and lava domes. This volcanism is part of the volcanic arc related to the interaction between the Nazca and South American plates. This interaction has led to a transtensional tectonic environment represented by pull-apart basins linked to the so-called Algeciras Fault System. This study integrates different techniques including field geology, petrography, mineral chemistry, whole-rock chemistry and geothermobarometric analysis in order to know the compositional characteristics and reconstruct the evolution of the magmas that gave rise to several volcanoes in the field: Guayapungo, Yaku, Mujundinoy Sur and Fuisanoy volcanoes. This study is the starting point to understand the possible future activity in the field. The eruptive products associated with these volcanoes correspond to concentrated and dilute pyroclastic density currents and lava flows, the latter predominating throughout the field. Petrographically, all the studied rocks are porphyritic, with olivine (Fo&lt;sub&gt;71–90&lt;/sub&gt;), clinopyroxene (Wo&lt;sub&gt;33–48&lt;/sub&gt;, En&lt;sub&gt;36–54&lt;/sub&gt;, Fe&lt;sub&gt;7–16&lt;/sub&gt;), orthopyroxene (Wo&lt;sub&gt;3–5&lt;/sub&gt;, En&lt;sub&gt;68–71&lt;/sub&gt;, Fe&lt;sub&gt;24–28&lt;/sub&gt;), plagioclase (An&lt;sub&gt;26–82&lt;/sub&gt;), amphibole (magnesiohastingsite and tschermakite) and Fe-Ti oxides as mineral phases embedded in a microcrystalline, cryptocrystalline and glassy groundmass. They present glomeroporphyritic texture in olivine and pyroxene, zoning in plagioclase, skeletal in olivine and pyroxene, and spinifex-like texture in pyroxene. Fluidal and serial textures are also common. Fe-Ti oxides are present as a minor phase in all volcanoes. Chemically, the volcanoes are basaltic and basaltic andesite in composition and display calc-alkaline affinity, typical of subduction environments. Geothermobarometric analyses indicate that the crystallisation conditions for olivine were 1188–1137 °C, for clinopyroxene 1199–1015 °C and 1.7–0.2 GPa and for plagioclase 1127–1077 °C and 0.6–0.2 GPa. The analyses indicate that the magmas share a common origin at the asthenosphere-lithosphere boundary and that fractional crystallisation was the most important magmatic evolution process during the magma ascent. The crystallisation conditions of the mineral phases indicate olivine, followed by clinopyroxene, as the first to start forming at the mantle-crust boundary (64–7 km), while plagioclase crystallised only at cortical levels (24–7 km). Chemical data and crystallisation conditions indicate that the Guayapungo volcano ascended directly from the mantle and experienced a rapid ascent from 15 km to the surface. The lack of crystallisation, in addition to the presence of amphibole xenocrysts, indicates that the Yaku and Mujundinoy Sur magmas experienced mild assimilation. Crystallisation conditions and further evolution at Fuisano","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108312"},"PeriodicalIF":2.4,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive characterization and geochemical alteration pathways of drill core from the Humu'ula Groundwater Research Project, Hawaii, USA: I. Pohakuloa Training Area","authors":"Pooja Sheevam,&nbsp;Wendy M. Calvin","doi":"10.1016/j.jvolgeores.2025.108311","DOIUrl":"10.1016/j.jvolgeores.2025.108311","url":null,"abstract":"<div><div>Scientific analysis of the PTA-2 drill core focuses on the investigation of mafic mineralogy through long-wave infrared (LWIR) spectroscopy, laboratory scanning electron microscopy with energy-dispersive spectroscopy (SEM EDS), and bulk X-ray fluorescence (XRF) geochemical analysis. We performed both LWIR and short-wave infrared (SWIR) imaging of thin sections and cut sections at high spatial resolution. These analyses complement prior work and provide additional information in order to understand the mineralogical transformations and geochemical processes that have occurred in the subsurface. LWIR spectroscopy allowed us to quantify specific mineral phases prevalent in shield phase basalts – which are largely comprised of Ca-feldspars, pyroxenes, and olivine. Collected spectra also showed the influence of alteration components on the spectral signatures. New analyses using SEM EDS and bulk XRF geochemistry, augment the spectroscopy and offer valuable insights into the mineralogy and fluid-rock interactions. Petrographic images confirmed the varying mineral textures of basalt, ranging from fine-grained, to more prominent phenocrysts in the form of olivine cumulates. Data acquired from whole rock geochemistry was instrumental in determining fluid-rock interactions by showing that elemental components are not lost with alteration. This study provides the first comprehensive analysis of subsurface drill core away from active margins, and a foundation for further subsurface core logging and research.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108311"},"PeriodicalIF":2.4,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparison of volcanic ash source term characteristics estimated by source inversion and plume rise modelling methods: Raikoke 2019","authors":"Natalie J. Harvey ,&nbsp;Michael Herzog ,&nbsp;Helen F. Dacre ,&nbsp;Helen N. Webster","doi":"10.1016/j.jvolgeores.2025.108304","DOIUrl":"10.1016/j.jvolgeores.2025.108304","url":null,"abstract":"<div><div>Predictions of volcanic ash location and concentration following an eruption rely heavily on estimates of source term characteristics including mass eruption rate, vertical distribution of ash and particle size distribution. These characteristics can be provided by several methods including (i) preset values based on historical data, (ii) near-source plume rise model simulations, (iii) a combination of satellite retrievals and long-range dispersion model simulations (known as source inversion). For the first time, this study presents a comparison of source term characteristics from these different methods. The study focuses on the 2019 Raikoke eruption and analysis of the volcanic ash cloud 150 km downwind from the volcano vent, representing an effective source term for the dispersion of ash in the distal volcanic cloud. Results indicate good agreement in the vertical distribution of ash between the plume rise and source inversion methods but large differences in estimates of the horizontal mass flux at this distance. The plume rise model demonstrates the rapid sedimentation and deposition of coarse (<span><math><mo>&gt;</mo><mn>100</mn><mi>μ</mi><mi>m</mi></math></span> diameter) ash particles close to the volcano vent resulting in a particle size distribution comparable to the preset distribution used operationally by the London VAAC at this range. These results suggest that source inversion can provide a computationally cheaper alternative to the 3D plume rise method for estimating the vertical distribution of ash, and that the assumption of near-source fallout of coarse particles in the preset particle size distribution holds fairly well. Further investigations are recommended including particle aggregation effects to understand differences in estimates of the effective mass eruption rate.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"462 ","pages":"Article 108304"},"PeriodicalIF":2.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}