Geochemistry Geophysics Geosystems最新文献

{"title":"Hydrogen Diffusion in Garnet: Insights From Atomistic Simulations","authors":"Xin Zhong,&nbsp;Felix Höfling,&nbsp;Timm John","doi":"10.1029/2024GC011951","DOIUrl":"https://doi.org/10.1029/2024GC011951","url":null,"abstract":"<p>Garnet has been widely used to decipher the pressure-temperature-time history of rocks, but its physical properties such as elasticity and diffusion are strongly affected by trace amounts of hydrogen. Experimental measurements of H diffusion in garnet are limited to room pressure. We use atomistic simulations to study H diffusion in perfect and defective garnet lattices, focusing on protonation defects at the Si and Mg sites, which are shown to be energetically favored. Transient trapping of H renders ab-initio simulations of H diffusion computationally challenging, which is overcome with machine learning techniques by training a deep neural network that encodes the interatomic potential. Our results from such deep potential molecular dynamics (DeePMD) simulations show high mobility of hydrogen in defect-free garnet lattices, whereas H diffusivity is significantly diminished in defective lattices. Tracer simulations focusing on H alone highlight the vital role of atomic vibrations of heavier atoms like Mg on the release of H atoms. Two regimes of H diffusion are identified: a diffuser-dominated regime at high hydrogen content with low activation energies due to saturation of vacancies by hydrogen, and a vacancy-dominated regime at low hydrogen content with high activation energies due to trapping of H atoms at vacancy sites. These regimes account for experimental observations, such as a H-concentration dependent diffusivity and the discrepancy in activation energy between deprotonation and D-H exchange experiments. This study underpins the crucial role of vacancies in H diffusion and demonstrates the utility of machine-learned interatomic potentials in studying kinetic processes in the Earth's interior.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011951","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404345","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":"Strain Localization and Seismic Properties in the Heterogeneous Ailaoshan-Red River Shear Zone, Southeast Asia","authors":"Junyu Li,&nbsp;Shuyun Cao","doi":"10.1029/2024GC011929","DOIUrl":"https://doi.org/10.1029/2024GC011929","url":null,"abstract":"<p>Strain localization is crucial in developing crustal-scale shear zones; however, a systematic analysis of deformation characteristics and their impact on seismic properties is still lacking. This study provides a comprehensive analysis of migmatites and granitic mylonites in the Ailaoshan-Red River shear zone (ASRR-SZ), incorporating detailed field observations, microstructure analysis, mineral crystallographic preferred orientations, rheological parameters, and seismic properties. Pre-existing compositional and mechanical anisotropies significantly influence strain localization in the ASRR-SZ. The southern part of the ASRR-SZ is primarily characterized by crustal anatexis, suggesting these regions as potential initiation sites for strain localization. Strain characteristics in the ASRR-SZ manifest in deformation temperatures (three ranges, ∼400–440°C, ∼470–500°C, and ∼730°C), differential stress (concentrated at 15.9–65.1 MPa), and strain rate (concentrated at 10⁻¹³–10⁻¹¹ s⁻¹). Notably, strain localization significantly alters the rock fabric and further affects the seismic properties of rocks. Significant differences in Vp values and orientations are noted between melanosomes (anisotropy of P-waves: AVp = 6.8%–17.9%, Max. Vp along the <i>X</i>-axis) and leucosomes (AVp = 3.4%–3.7%, Max. Vp along the <i>Y</i>-axis). The seismic velocities and AVp in granitic mylonites exhibit a linear correlation with quartz content, and deformation conditions strongly influence their orientation. For a middle to lower crust thickness of ∼25 km, the delay times between fast and slow polarized shear waves are 0.3–0.66 s for granitic mylonites, 0.37–0.7 s for melanosomes, 0.22–0.31 s for leucosomes, 0.27–0.58 s for amphibolites, and 0.57–2.7 s for schists. The average delay time (<i>dt</i>) of these rocks along the ASRR-SZ accounts for the observed delay time (<i>dt</i> = 0.58 s).</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011929","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143397067","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 Characteristics of Highly Serpentinized Peridotite in the Iberia Abyssal Plain and Implications for Marine Magnetic Anomalies","authors":"Yuzhen Zhang,&nbsp;Zhaoxia Jiang,&nbsp;Kai Su,&nbsp;Mark J. Dekkers,&nbsp;Sanzhong Li,&nbsp;Qingsong Liu","doi":"10.1029/2024GC012035","DOIUrl":"https://doi.org/10.1029/2024GC012035","url":null,"abstract":"<p>Serpentinization, a consequence of water-rock interaction in mafic and ultramafic rocks, refers to the hydrothermal alteration of olivine and pyroxene with serpentine as the typical product. Magnetite is produced in variable amounts during this serpentinization process. Here, we conducted a systematic rock magnetic study on the serpentinite of Ocean Drilling Program (ODP) Hole 1070A from the Iberia Abyssal Plain. From bottom to top, three units are distinguished rock-magnetically: (a) serpentinized peridotite dominated by single-domain (SD) ± multidomain (MD) magnetite particles; (b) gabbro with SD ± vortex state magnetite; (c) breccia dominated by MD ± vortex and SD ± vortex state maghemite/hematite and magnetite. Samples of the three units are highly serpentinized with serpentinization degrees &gt;60%. The magnetite content increases exponentially with the degree of serpentinization. Two phases of serpentinization are proposed: (a) massive serpentinization that occurred before mantle exhumation and (b) maghemitization-serpentinization that occurred near or at the seafloor after the final exhumation of mantle peridotites. The latter reduces the magnetization of the breccia unit significantly. Serpentinized peridotite associated with strong magnetization is the dominant contributor to the marine magnetic anomalies in ocean to continent transition areas.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143389032","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":"Paleo-Earthquake Fingerprints and Along-Strike Slip Variation of the Silent Mt. Morrone Normal Fault (Central Italy): A Structural-Geochemical Approach","authors":"S. Bello,&nbsp;P. Galli,&nbsp;M. G. Perna,&nbsp;E. Peronace,&nbsp;P. Messina,&nbsp;G. Rosatelli,&nbsp;C. Andrenacci,&nbsp;G. Lavecchia,&nbsp;F. Pietrolungo,&nbsp;A. Consalvo,&nbsp;V. Mouslopoulou,&nbsp;F. Brozzetti","doi":"10.1029/2024GC011868","DOIUrl":"https://doi.org/10.1029/2024GC011868","url":null,"abstract":"<p>This study provides insights into the tectonic evolution of the normal Mt Morrone Fault System (MMFS) in Central Italy and highlights the utility of multidisciplinary approaches in reconstructing the seismic history of dormant fault systems. The MMFS comprises two parallel normal faults that traverse the western slope of Mt. Morrone, and although the system can produce <i>M</i> &gt; 6 earthquakes, it has been aseismic in post Roman times. Here, we combine geochemical analysis of carbonate fault-scarp samples with new structural fault data and Lidar-based topographic analysis to provide new constraints on fault geometries and kinematics, the paleo-earthquake history of MMFS since the Last Glacial Maximum and its slip rates. Structural analysis reveals kinematic similarities between the two parallel strands, reflecting their response to the same stress regime. Rare Earth Elements analyses on 53 limestone samples reveal a minimum of eight concentration fluctuations upscarp, here interpreted as tectonic exhumation of the fault scarp due to post LGM earthquakes. Slip per event ranges from 30 to 110 cm typical of earthquakes with 6.3 ≤ <i>M</i> ≤ 6.8. Lidar analysis reveals triangular slip profiles on both fault strands. We estimate that an earthquake with an average <i>M</i> = 6.5–6.6 would have a recurrence interval of ∼2,125 ± 125 years. Slip rates were calculated to be 0.5–0.65 mm/yr on the lower and 0.65–0.7 mm/yr on the upper fault strand, with the combined system having slip rates of 0.62–0.69 mm/yr. Our findings indicate that both strands of the MMFS are active and accumulate slip interdependently, a finding that is critical for seismic hazard assessment.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011868","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143389034","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":"Anomalous Sediment Consolidation and Alteration From Buried Incoming Plate Seamounts Along the Cascadia Margin","authors":"Michelle K. Lee,&nbsp;Suzanne M. Carbotte,&nbsp;Shuoshuo Han,&nbsp;Brandon Shuck,&nbsp;Pinar Gurun,&nbsp;Brian Boston,&nbsp;Mladen Nedimovic,&nbsp;Harold Tobin,&nbsp;Ben Norvell,&nbsp;Glenn Spinelli","doi":"10.1029/2024GC011949","DOIUrl":"https://doi.org/10.1029/2024GC011949","url":null,"abstract":"<p>Oceanic plate seamounts are believed to play an important role in megathrust rupture at subduction zones, although consistent relationships between subducting seamounts and plate interface seismicity patterns are not found. While most studies focus on impacts linked to their topography, seamounts are also sites of heterogeneity in incoming plate sediments that may contribute to megathrust properties. Here, we characterize incoming plate sediments along the Cascadia subduction zone using new high-resolution seismic images and compressional wave (<i>V</i>_<i>p</i>) models from the CASIE21 multi-channel-seismic experiment. Nine fully-to-partially buried seamounts are identified seaward of the deformation front within a region of thick Plio-Pleistocene sediment where the Juan de Fuca plate is bending into the subduction zone. Anomalously high <i>V</i>_<i>p</i> sediment blankets two seamounts offshore Washington-Central Oregon, with wavespeeds reaching 36% and 20% higher than adjacent sediment. Fluid seepage and temperatures warm enough for smectite diagenesis extending to shallow depths are inferred from heat flow studies and we attribute <i>V</i>_<i>p</i> anomalies to sediment cementation linked primarily to smectite dehydration. Signatures of fluid seepage above seamounts are also identified offshore Vancouver Island, but anomalously low <i>V</i>_<i>p</i> sediment below distinct reverse polarity reflections are found, indicating trapped fluids, and cooler basement temperatures are inferred. Landward of one seamount, a zone of enhanced sediment compaction is found, consistent with the predicted stress modulating effects of seamount subduction. These new findings of variations in sediment diagenesis and strength around seamounts prior to subduction may contribute to the diverse megathrust frictional properties and seismicity patterns evident at subducting seamounts.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011949","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143389036","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":"En-échelon Rifting and Origin of the Volcanism in the Comoros","authors":"P. Boymond,&nbsp;N. Feuillet,&nbsp;I. Thinon,&nbsp;L. Scholtès,&nbsp;S. Zaragosi,&nbsp;S. Leroy,&nbsp;A. Lemoine","doi":"10.1029/2024GC011576","DOIUrl":"https://doi.org/10.1029/2024GC011576","url":null,"abstract":"<p>Two volcanic provinces have been recently discovered during the SISMAORE oceanographic cruise in the Comoros archipelago in the North Mozambique Channel between Madagascar and East Africa: N’Droundé, along the North-eastern insular slopes of Grande Comores Island and Mwezi, in the abyssal plain, north-east of Mayotte and Anjouan islands. By combining bathymetry and backscatter data, high-resolution seismic reflection and sub-bottom profiles, we have identified and mapped various tectonic (faults, forced folds) and volcanic structures (lava flows, edifices, sills, dykes) at several spatial scales on the seabed and in cross-section within the sedimentary cover. We have characterized the volcano-tectonic structures (geometry, segmentation, and kinematics) to better understand the link (geometry, chronology) between tectonic and volcanic processes. We show that volcanic and tectonic features are controlled by tectonic processes and vice-versa. Ridges, volcanic cones and lava flows are set up along fissures and dikes during main rifting events to accommodate a N40°E regional extension within an E-W right lateral shear transfer zone. The volcano tectonic features are Plio-Pleistocene. This transfer zone lies between the offshore branch of the East African rift system and Malagasy grabens and may have formed when the East African rifts propagated offshore. We evidence a major rifting episode in the last Ma. The estimated volume and flux of extruded lavas show that the volcanism of the Comoros could be related to shallow tectonic processes.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011576","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143380027","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":"U-Pb Geochronology and Lu-Hf Isotopic Characterization of the Canadian High Arctic Large Igneous Province (HALIP): Comparison to Oceanic Plateau Magmatism","authors":"D. M. Dockman,&nbsp;T. Hadlari,&nbsp;D. G. Pearson,&nbsp;L. M. Heaman,&nbsp;C. Sarkar,&nbsp;K. Dewing","doi":"10.1029/2024GC011762","DOIUrl":"https://doi.org/10.1029/2024GC011762","url":null,"abstract":"<p>Recent high-precision geochronological studies have delineated three main pulses of basaltic magmatism between ca. 130-80 Ma in the Cretaceous High Arctic Large Igneous Province (HALIP) in northern Canada. Here we report new U-Pb TIMS baddeleyite and zircon dates for samples from Axel Heiberg and Ellesmere Islands, which further support the duration and pulsed nature of the magmatism previously documented. We add new LA-ICPMS U-Pb zircon dates on samples analyzed in a previous study to help resolve age heterogeneity observed in some samples. We also report the first LA-ICPMS zircon Lu-Hf results from HALIP intrusives to better constrain the HALIP mantle source composition. Initial εHf zircon results for five HALIP basalts with minimal evidence for continental crustal contamination from the Canadian Arctic Islands range from +9.0 to +14.7, and indicate extraction from a depleted mantle source similar to plume-derived oceanic plateaux such as Kerguelen.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011762","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143380026","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 Lithosphere-Asthenosphere System Beneath the North Atlantic and Surroundings: Results From Multi-Observable Probabilistic Inversions","authors":"Farshad Salajegheh,&nbsp;Juan Carlos Afonso,&nbsp;Alexander Minakov,&nbsp;Parviz Ajourlou,&nbsp;Carmen Gaina,&nbsp;Olga Ortega-Gelabert","doi":"10.1029/2024GC011724","DOIUrl":"https://doi.org/10.1029/2024GC011724","url":null,"abstract":"<p>The North Atlantic region is a complex geodynamic setting that comprises multiple continental blocks, sedimentary basins, mid-ocean ridge systems and prominent hotspots. Recent geophysical surveys of the near-surface have enhanced our understanding of crustal elements and the shallow lithosphere. However, our knowledge of the deep lithospheric structure and the physical state and dynamics of the upper mantle is still limited. Here, we exploit the combined sensitivity of surface-wave data, geoid anomalies, absolute topography and surface heat flow to obtain full thermochemical models of the region from the surface down to 350 km. We jointly invert these data sets using a simulation-based, multi-observable probabilistic framework. We validate our results with independent thermobarometric and chemical information from mantle xenoliths and test the effects of using different seismic models on the inversion results. Our model reveals an intricate sublithospheric flow system, driven by the interaction of deep upwellings with the highly irregular lithospheric structure. We corroborate that the main thermal anomaly in the sublithospheric mantle shows a tilted geometry, moving toward Greenland with depth. We reveal that this large-scale anomaly transition into a more complex pattern once it reaches depths of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>150 km beneath the North Atlantic. Small-scale downwellings originate from the margins of continental domains, resulting in a complex circulation pattern that limits the radial spread of the deep upwellings and preferentially focuses them within regions of thin lithosphere along a N–S direction. Distinct compositional anomalies in the Greenland lithosphere delineate the North Atlantic Craton, the Nagssugtoqidian mobile belt, and the covered remnants of the Disko Craton. In continental Europe, the East European Craton shows clear indications of depletion in incompatible elements, with the Kola-Karelian cratonic region showing the highest levels of depletion. Our model serves as a base to make interpretations on the enigmatic paleotectonic history of the North-Atlantic region.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011724","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143380028","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":"How Phase Transitions Impact Changes in Mantle Convection Style Throughout Earth's History: From Stalled Plumes to Surface Dynamics","authors":"Ranpeng Li,&nbsp;Juliane Dannberg,&nbsp;Rene Gassmöller,&nbsp;Carolina Lithgow-Bertelloni,&nbsp;Lars Stixrude","doi":"10.1029/2024GC011600","DOIUrl":"https://doi.org/10.1029/2024GC011600","url":null,"abstract":"<p>Mineral phase transitions can either hinder or accelerate mantle flow. In the present day, the formation of the bridgmanite + ferropericlase assemblage from ringwoodite at 660 km depth has been found to cause weak and intermittent layering of mantle convection. However, for the higher temperatures in Earth's past, different phase transitions could have controlled mantle dynamics. We investigate the potential changes in convection style during Earth's secular cooling using a new numerical technique that reformulates the energy conservation equation in terms of specific entropy instead of temperature. This approach enables us to accurately include the latent heat effect of phase transitions for mantle temperatures different from the average geotherm, and therefore fully incorporate the thermodynamic effects of realistic phase transitions in global-scale mantle convection modeling. We set up 2-D models with the geodynamics software <span>Aspect</span>, using thermodynamic properties computed by HeFESTo, while applying a viscosity profile constrained by the geoid and mineral physics data and a visco-plastic rheology to reproduce plate-like behavior and Earth-like subduction morphologies. Our model results reveal the layering of plumes induced by the wadsleyite to garnet (majorite) + ferropericlase endothermic transition (between 450 and 590 km depth and over the 2000–2500 K temperature range). They show that this phase transition causes a large-scale and long-lasting temperature elevation in a depth range of 500–650 km depth if the potential temperature of the mantle is higher than 1800 K, indicating that mantle convection may have been partially layered in Earth's early history.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011600","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362541","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":"Explosive Ocean Island Volcanism Explained by High Magmatic Water Content Determined Through Nominally Anhydrous Minerals","authors":"Harri Geiger,&nbsp;Franz Weis,&nbsp;Valentin R. Troll,&nbsp;Frances M. Deegan,&nbsp;Henrik Skogby,&nbsp;Juan Carlos Carracedo","doi":"10.1029/2024GC012013","DOIUrl":"https://doi.org/10.1029/2024GC012013","url":null,"abstract":"<p>Ocean island basalt (OIB) magmas are generally water poor and usually contain less than 1 wt.% of H₂O. Explosive eruption styles are therefore rare. When explosive eruptions occur, they are thought to be driven by either volatile-enriched mantle sources or by gas segregation processes during magma differentiation. Here we report on crystal- and water-rich porphyritic basanites and ankaramites from El Hierro in the Canary Islands, Spain, that erupted inside the El Golfo giant landslide collapse embayment that formed at ≥39 ka. Using rock and mineral chemistry in combination with H₂O contents of nominally anhydrous minerals (olivine and clinopyroxene), we show that despite their relatively primitive composition, the post-collapse ankaramites are not primary mantle melts. Instead, they record high crystal contents as well as unusually high water contents of up to 3.20 ± 0.64 wt.% H₂O, and likely represent a normally inaccessible snapshot of dense crystal-rich magma compositions that reside in the sub-island underplating zone. We hypothesize that their eruption was facilitated by sudden decompression from crustal unloading, implying that the El Golfo landslide may have affected the deeper portions of the plumbing system and triggered the ascent of volatile-rich, crystal-laden magmas from the underplating zone. We propose that some “wet” and explosive ocean island eruptions might result from the ascent of deep-seated water-rich magmas in the aftermath of vertical unloading and associated decompression.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362549","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}