Geochemistry Geophysics Geosystems最新文献

{"title":"(De)hydration Front Propagation Into Zero-Permeability Rock","authors":"Stefan M. Schmalholz,&nbsp;Lyudmila Khakimova,&nbsp;Yury Podladchikov,&nbsp;Erwan Bras,&nbsp;Philippe Yamato,&nbsp;Timm John","doi":"10.1029/2023GC011422","DOIUrl":"https://doi.org/10.1029/2023GC011422","url":null,"abstract":"<p>Hydration and dehydration reactions play pivotal roles in plate tectonics and the deep water cycle, yet many facets of (de)hydration reactions remain unclear. Here, we study (de)hydration reactions where associated solid density changes are predominantly balanced by porosity changes, with solid rock deformation playing a minor role. We propose a hypothesis for three scenarios of (de)hydration front propagation and test it using one-dimensional hydro-mechanical-chemical models. Our models couple porous fluid flow, solid rock volumetric deformation, and (de)hydration reactions described by equilibrium thermodynamics. We couple our transport model with reactions through fluid pressure: the fluid pressure gradient governs porous flow and the fluid pressure magnitude controls the reaction boundary. Our model validates the hypothesized scenarios and shows that the change in solid density across the reaction boundary, from lower to higher pressure, dictates whether hydration or dehydration fronts propagate: decreasing solid density causes dehydration front propagation in the direction opposite to fluid flow while increasing solid density enables both hydration and dehydration front propagation in the same direction as fluid flow. Our models demonstrate that reactions can drive the propagation of (de)hydration fronts, characterized by sharp porosity fronts, into a viscous medium with zero porosity and permeability; such propagation is impossible without reactions, as porosity fronts become trapped. We apply our model to serpentinite dehydration reactions with positive and negative Clapeyron slopes and granulite hydration (eclogitization). We use the results of systematic numerical simulations to derive a new equation that allows estimating the transient, reaction-induced permeability of natural (de)hydration zones.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011422","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142152189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum-Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical-Petrological Thermochemical Inversion","authors":"A. El-Sharkawy,&nbsp;T. H. Hansteen,&nbsp;C. Clemente-Gomez,&nbsp;J. Fullea,&nbsp;S. Lebedev,&nbsp;T. Meier","doi":"10.1029/2023GC011017","DOIUrl":"https://doi.org/10.1029/2023GC011017","url":null,"abstract":"<p>We compile an extensive catalog comprising geochemistry and ages of Cenozoic volcanic provinces in the Mediterranean region, distinguishing between three groups according to the geochemistry of magmatic rocks: intraplate (IVP), subduction-related (SRVP), and mixed-origin volcanic provinces (MVP; intraplate with subduction imprint). In order to relate their spatial distribution to properties of the lithosphere-asthenosphere system, we determine temperature-depth profiles by integrated geophysical-petrological inversion at representative locations, using Rayleigh and Love wave phase velocities, heat flow, rock densities, and accounting for thermochemical conditions. The results confirm the occurrence of thin lithosphere (&lt;100 km) above warm asthenosphere (&gt;1,300°C) in areas of low shear-wave velocities in the shallow upper mantle. Nine shallow asthenospheric volumes (SAVs) between 70 and 300 km depths are identified, forming a partly interconnected belt across the Circum-Mediterranean. A remarkable colocation exists between the SAVs and the intraplate and mixed-origin volcanic provinces (IMVPs). Whereas dense networks of IMVPs have formed above the SAVs, IMVPs are absent in areas of thick mantle lithosphere. Magmatic activity in IMVPs at 60–70 Ma indicates that several SAVs existed already in the Paleogene (Central European, Adriatic, Western Mediterranean, and Moesian SAVs). The formation of SAVs is related either to asthenospheric upwelling caused by slab rollback and back-arc extension (Aegean-Anatolian, Moesian, Pannonian, Western Mediterranean SAVs), or to thermal upwelling (Adriatic, Central European, Middle East [MEA], North African, Rhine-Rhone SAVs), with some of the latter coupled partly with continental rifting (Central European, MEA, North African, Rhine Rhone SAVs).</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142152188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Anatomy of the Emeishan Mantle Plume Head: Insights From New Geochronologic, Geochemical, and Geologic Data","authors":"Hongbo Li,&nbsp;Zhaochong Zhang,&nbsp;Ran Liu,&nbsp;Marc K. Reichow,&nbsp;Jiang Zhu,&nbsp;Richard Ernst,&nbsp;M. Santosh,&nbsp;Wei Wang,&nbsp;Changquan Li,&nbsp;Botong Li","doi":"10.1029/2024GC011635","DOIUrl":"https://doi.org/10.1029/2024GC011635","url":null,"abstract":"<p>The link between mantle plumes and the formation of large igneous provinces (LIPs) is well established although the anatomy of these remains equivocal. Recent experimental studies and geophysical data suggest that the mantle plume head is more likely to be irregular and asymmetric, rather than an axisymmetric flattened disk. The Emeishan large igneous province (ELIP) provides a unique opportunity to test this hypothesis. According to robust petrographic, geochronologic, and geochemical evidence from the late Permian basalts in the Sichuan Basin, and in conjunction with a comprehensive compilation of geologic maps and published geochemical data from the ELIP, we identified several giant radial “fingering” structures. Based on the shallow mantle source from the center to margin in the ELIP and relief of the lithosphere-asthenosphere boundary, we propose a new mantle plume model to explain the evolution of the Emeishan plume periphery, where narrow finger-like protrusions and plumelets developed outwards from the main body of the plume to the edges of the flattened plume head. Dragged fingers might have been torn apart into some plumelets, which dispersed and were trapped beneath the thinnest lithosphere relief, and eventually erupted to form small-scale flood basalt in the Outer Zone of the ELIP.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011635","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142152191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The Role of Upper Mantle Forces in Post-Subduction Tectonics: Plumelet and Active Rifting in the East Anatolian Plateau","authors":"Ebru Şengül Uluocak,&nbsp;Russell N. Pysklywec,&nbsp;Andrea Sembroni,&nbsp;Sascha Brune,&nbsp;Claudio Faccenna","doi":"10.1029/2024GC011639","DOIUrl":"https://doi.org/10.1029/2024GC011639","url":null,"abstract":"<p>The spatiotemporal interaction of large- and regional-scale upper mantle forces can prevail in collisional settings. To better understand the role of these forces on post-subduction tectonics, we focus on mantle dynamics in the East Anatolian Plateau, a well-documented segment of the Arabian-Eurasian continental collision zone. Specifically, we analyze multiple forces in the upper mantle, which have not been considered in previous studies in this region. To this end, we use a state-of-the-art 3D instantaneous geodynamic model to quantify the dynamics of thermally defined upper mantle structures derived from seismic tomography data. Results reveal a prominent SW-NE-oriented mantle flow from the Arabian foreland to the Greater Caucasus–a plumelet–through a lithospheric channel under the East Anatolian Plateau. This plumelet induces localized dynamic topography (∼500 m) around the extensional Lake Van province, favoring NE-directed compression and westward escape of the Anatolian plate. We suggest that the Lake Van region is an active magma-rich intraplate rift in the Africa-Arabia-Anatolian plume-rift system. The rift zone was probably initiated by Neotethyan subduction-related forces and has been reactivated and/or sustained by the plumelet-induced convective support. Our findings are consistent with numerous observations, including the recent low-ultralow seismic velocities with a SW-NE splitting anisotropy pattern, geochemical and petrological studies, and local kinematics showing upper mantle-induced extensional tectonics in the collisional region.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011639","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142152232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Disentangling the Roles of Subducted Volatile Contributions and Mantle Source Heterogeneity in the Production of Magmas Beneath the Washington Cascades","authors":"K. J. Walowski,&nbsp;P. J. Wallace,&nbsp;S. M. DeBari,&nbsp;I. Wada,&nbsp;S. D. Shaw,&nbsp;J. Rea","doi":"10.1029/2024GC011587","DOIUrl":"https://doi.org/10.1029/2024GC011587","url":null,"abstract":"<p>The compositional diversity of primitive arc basalts has long inspired questions regarding the drivers of magmatism in subduction zones, including the roles of decompression melting, mantle heterogeneity, and the amount and composition of slab-derived materials. This contribution presents the volatile (H₂O, Cl, and S), major, and trace element compositions of melt inclusions from basaltic magmas erupted at three volcanic centers in the Washington Cascades: Mount St. Helens (two basaltic tephras, 2.0–1.7 ka), Indian Heaven Volcanic Field (two &lt;600 ka basaltic hyaloclastite tuffs), and Glacier Peak (late Pleistocene to Holocene basaltic tephra from Whitechuck and Indian Pass cones). Compositions corrected to be in equilibrium with mantle olivine display variability in Nb and trace element ratios indicative of mantle source variability that impressively spans nearly the entire range of arc magmas globally. All volcanic centers have magmas with H₂O and Cl contributions from the downgoing plate that overlap with other Cascade Arc segments. Volatile abundances and trace element ratios support a model of melting of a highly variably mantle wedge driven by a subduction component of variably saline fluid and/or slab partial melt. Magmas from Glacier Peak in northern Washington have unusually high Th/Yb ratios that are similar to Lassen region basalts, indicating possible contributions of “subcreted” metasediments that geophysical data suggest are not present beneath central Oregon and southern Washington. This data set adds to the growing inventory of primitive magma volatile concentrations and provides insight into spatial distributions of mantle heterogeneity and the role of slab components in the petrogenesis of arc magmas.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011587","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Fluid-Driven Shear Instabilities in the Subducted Oceanic Mantle at Intermediate Depths: Insights From Western Alps Meta-Ophiolites","authors":"J. Muñoz-Montecinos,&nbsp;S. Angiboust,&nbsp;C. Minnaert,&nbsp;A. Ceccato,&nbsp;L. Morales,&nbsp;J. Gasc,&nbsp;W. Behr","doi":"10.1029/2024GC011581","DOIUrl":"https://doi.org/10.1029/2024GC011581","url":null,"abstract":"<p>Serpentinites are major carriers of volatiles in deep subduction zones, releasing most fluids in the 500–650°C range. Despite fundamental implications for mass transfer and intermediate-depth seismicity, the mechanical role of these fluids is unclear. To characterize the mechanical role of fluids at (ultra)high-pressure conditions, we perform a petro-structural analysis on olivine-rich veins from the Western Alps meta-ophiolite. Some veins formed through dilational and mixed dilational-shear fracturing without significant shear-related deformation. However, field and microstructural observations indicate transient shearing and dilational fracturing at high pore fluid pressures. These include: (a) foliated sheared veins; (b) newly formed olivine and Ti-clinohumite within mineral lineations coating sheared veins and shear bands; (c) Olivine and Ti-clinohumite mineral fibers sealing porphyroclasts; (d) mutual crosscutting relationships among dilational and shear features. Dilational veins prevail in low-strain areas, while sheared veins and shear bands dominate within high-strain zones toward the ultramafic sliver boundaries. These strain variations underscore the role of local stress regimes during serpentinite dehydration. Consequently, areas experiencing stronger shear stresses around large-scale blocks or mechanical weakening during fluid circulation are prone to draining overpressurized fluids. These interface-parallel and fracture-controlled pathways thus facilitate fluid escape from the dehydrating downgoing slab. Transient events of dilational fracturing and brittle-ductile shearing, along with strain localization in highly comminuted olivine-bearing sheared veins, may have resulted from strain rate bursts potentially related to (sub)seismic deformation. These observations are in line with geophysical data indicating high pore fluid pressures within the intermediate-depth seismicity region.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011581","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142050519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Magnetic Hysteresis Properties of Magnetite: Trends With Particle Size and Shape","authors":"Greig A. Paterson,&nbsp;Roberto Moreno,&nbsp;Adrian R. Muxworthy,&nbsp;Lesleis Nagy,&nbsp;Wyn Williams,&nbsp;Lisa Tauxe","doi":"10.1029/2024GC011461","DOIUrl":"https://doi.org/10.1029/2024GC011461","url":null,"abstract":"<p>Magnetic hysteresis measurements are routinely made in the Earth and planetary sciences to identify geologically meaningful magnetic recorders, and to study variations in present and past environments. Interpreting magnetic hysteresis data in terms of domain state and paleomagnetic stability are major motivations behind undertaking these measurements, but the interpretations remain fraught with challenges and ambiguities. To shed new light on these ambiguities, we have undertaken a systematic micromagnetic study to quantify the magnetic hysteresis behavior of room-temperature magnetite as a function of particle size (45–195 nm; equivalent spherical volume diameter) and shape (oblate, prolate and equant); our models span uniformly magnetized single domain (SD) to non-uniformly magnetized single vortex (SV) states. Within our models the reduced magnetization associated with SV particles marks a clear boundary between SD (≥0.5) and SV (&lt;0.5) magnetite. We further identify particle sizes and shapes with unexpectedly low coercivity and coercivity of remanence. These low coercivity regions correspond to magnetite particles that typically have multiple possible magnetic domain state configurations, which have been previously linked to a zone of unstable magnetic recorders. Of all the hysteresis parameters investigated, transient hysteresis is most sensitive to particles that exhibit such domain state multiplicity. When experimental transient hysteresis is compared to paleointensity behavior, we show that increasing transience corresponds to more curved Arai plots and less accurate paleointensity results. We therefore strongly suggest that transient behavior should be more routinely measured during rock magnetic investigations.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011461","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142050566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Tectonic Reorganization of the Caribbean Plate System in the Paleogene Driven by Farallon Slab Anchoring","authors":"Ethan M. Conrad,&nbsp;Claudio Faccenna,&nbsp;Adam F. Holt,&nbsp;Thorsten W. Becker","doi":"10.1029/2024GC011499","DOIUrl":"https://doi.org/10.1029/2024GC011499","url":null,"abstract":"<p>The tectonic configuration of the Caribbean plate is defined by inward-dipping double subduction at its boundaries with the North American and Cocos plates. This geometry resulted from a Paleogene plate reorganization, which involved the abandonment of an older subduction system, the Great Arc of the Caribbean (GAC), and conversion into a transform margin during Lesser Antilles (LA) arc formation. Previous models suggest that a collision between the GAC and the Bahamas platform along the North American passive margin caused this event. However, geological and geophysical constraints from the Greater Antilles do not show a large-scale compressional episode that should correspond to such a collision. We propose an alternative model for the evolution of the region where lower mantle penetration of the Farallon slab promotes the onset of subduction at the LA. We integrate tectonic constraints with seismic tomography to analyze the timing and dynamics of the reorganization, showing that the onset of LA subduction corresponds to the timing of Farallon/Cocos slab penetration. With numerical subduction models, we explore whether slab penetration constitutes a dynamically feasible set of mechanisms to initiate subduction in the overriding plate. In our models, when the first slab (Farallon/Cocos) enters the lower mantle, compressive stresses increase at the eastern margin of the upper plate, and a second subduction zone (LA) is initiated. The resulting first-order slab geometries, timings, and kinematics compare well with plate reconstructions. More generally, similar slab dynamics may provide a mechanism not only for the Caribbean reorganization but also for other tectonic episodes throughout the Americas.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011499","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142045159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"South Atlantic Multi-Site Calibration of Coral Oxygen Isotope Paleothermometer","authors":"N. S. Pereira,&nbsp;C. M. Chiessi,&nbsp;S. Crivellari,&nbsp;K. H. Kilbourne,&nbsp;R. K. P. Kikuchi,&nbsp;B. P. Ferreira,&nbsp;R. J. A. Macêdo,&nbsp;M. C. M. dos Santos,&nbsp;M. G. Pereira,&nbsp;L. S. Neves da Rocha,&nbsp;A. N. Sial","doi":"10.1029/2023GC011395","DOIUrl":"https://doi.org/10.1029/2023GC011395","url":null,"abstract":"<p>Coral-based stable oxygen isotopes (δ¹⁸O) have been used as a proxy for sea surface temperature (SST) since the 1970s, and δ¹⁸O–SST calibration studies have been fundamental to assure robust and faithful SST reconstructions. Paleoclimatic studies based on corals from the tropical western South Atlantic (TWSA) are scarce, and the available coral species need to be calibrated to improve climate and environmental reconstructions. <i>Siderastrea stellata</i>, a slow-growing coral, is a potential species to be explored as a coral archive in the TWSA. We provide the first multi-site δ¹⁸O–SST calibration for the coral <i>S</i>. <i>stellata</i> from three locations at the TWSA: Todos os Santos Bay, Tamandaré and the Rocas Atoll. Pseudo-coral δ¹⁸O calculations derived from gridded SSS and SST show that the contributions of SSS and SST to coral δ¹⁸O are expected to be different at each site. Weighted least squares linear regressions performed between the δ¹⁸O and SST generated the following calibrations equations: δ¹⁸O = −0.18 (±0.02) × SST (°C) + 1.90 (±0.47) for Todos os Santos Bay; δ¹⁸O = −0.18 (±0.02) × SST (°C) + 1.54 (±0.67) for Tamandaré; and δ¹⁸O = −0.16 (±0.03) × SST (°C) + 1.24 (±0.71) for the Rocas Atoll. The δ¹⁸O-SST sensitivity of <i>S</i>. <i>stellata</i> from the TWSA is similar to that of other slow-growing species of the genus and consistent with the expected δ¹⁸O-SST sensitivity of other species reported in the literature. These calibrations will allow future SST reconstructions based on δ¹⁸O records from sub-fossil and fossil <i>S</i>. <i>stellata</i>, an abundant species in the TWSA.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Ongoing Activity at Hunga Submarine Volcano, Tonga: The Case for Better Monitoring of Submarine Volcanoes Worldwide","authors":"Sharon L. Walker,&nbsp;Cornel E. J. de Ronde","doi":"10.1029/2024GC011685","DOIUrl":"https://doi.org/10.1029/2024GC011685","url":null,"abstract":"<p>The powerful eruption of Hunga volcano (15-January-2022) excavated ∼6.3 km³ of pre-existing material, leaving behind an 855 m deep crater. The scientific and humanitarian response to this event was challenging due to the remote location, safety concerns, and COVID-19 pandemic restrictions. To investigate the status of ongoing eruptive/hydrothermal activity, this study used, for the first time, an un-crewed surface vessel operated remotely from &gt;16,000 km away to make direct water column measurements within the crater and map its structure in detail. Intense turbidity and oxidation-reduction potential (ORP) anomalies located ongoing activity at sites on the steep inside crater slopes near both remaining islands. Mid-water acoustic reflectors indicated ongoing degassing, and positive ORP anomalies suggested gas composition was dominated by CO₂. At least 75% of the crater rim is shallower than 100 m, so any exchange with the surrounding ocean is limited by the depths of breaches in the rim (185 m between the islands and 290 m on the ENE side). This post-eruption bathymetry results in accumulation of emission products within the deep crater. There were no indications of the ongoing activity visible at the ocean surface, which highlights the limitations and inherent biases associated with relying on discolored surface water and/or atmospheric disturbances to determine eruption start/end dates at submarine volcanoes. This study demonstrates the value and need to add repeat hydrothermal plume and bathymetric surveys to our toolbox for monitoring submarine volcanoes, and the potential for un-crewed, remotely operated vessels to contribute significantly to these efforts.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011685","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}