Geochemistry Geophysics Geosystems最新文献

{"title":"Petrological Evidence for Magma Mobilization Years Before the 2020/2021 Eruption of La Soufrière Volcano, St. Vincent","authors":"Michal Camejo-Harry,&nbsp;Jon Blundy,&nbsp;Euan J. F. Mutch,&nbsp;Thomas Hudson,&nbsp;John-Michael Kendall,&nbsp;Thomas Christopher,&nbsp;Rodrigo Contreras-Arratia,&nbsp;Joan L. Latchman,&nbsp;Leanka Henry","doi":"10.1029/2024GC012093","DOIUrl":"https://doi.org/10.1029/2024GC012093","url":null,"abstract":"<p>Anticipating the onset of the 2020/2021 effusive-explosive eruptive sequence at La Soufrière volcano, St. Vincent was challenging despite the established monitoring networks in operation. Here, we integrate petrological data to decipher retrospectively signs of imminent eruption from available pre-eruptive monitoring data. Using diffusion chronometry, we estimated the timescales over which magmas transported to the surface. We examined olivine crystals hosted in basaltic andesite scoria, categorizing them into four groups based on their textures (euhedral to anhedral) and core compositions (Fo_73–89). Multiply zoned olivine populations are tracked through a multi-stage journey from depth to surface corresponding to periods of magma ascent and accumulation years before eventual eruption. This correlates temporally with two phases of unrest from monitoring data: (a) a protracted <i>priming</i> phase (lasting more than a decade) manifesting in low-level seismicity, small crater transformations (rockfalls and new fumaroles) and an elevated CO₂ degassing signal; and (b) a subsequent <i>transition</i> phase, initiating just over a year before eruption with the onset of geophysical unrest in the form of discrete episodes of elevated seismicity and volcano inflation. Our findings provide new insight into the dynamics of magma mobilization at La Soufrière. We demonstrate that magmatic unrest in the roots of the sub-volcanic system precedes geophysical precursors by years, drawing connections between individually ambiguous surface signals over long timescales. Monitoring strategies optimized to detect early stages of magmatic unrest, such as identifying and locating rarer deep seismicity and routine sampling at the crater plume, could improve future responses to volcanic crises in St. Vincent.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012093","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822149","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":"Finite Element Method for Garnet Diffusion Chronometry","authors":"Hailin Wu,&nbsp;Lingsen Zeng,&nbsp;Rongfeng Ge,&nbsp;Wenbin Zhu","doi":"10.1029/2025GC012182","DOIUrl":"https://doi.org/10.1029/2025GC012182","url":null,"abstract":"<p>Crystal geometries and boundary conditions significantly influence garnet diffusion chronometry results, yet they are frequently overlooked and pose challenges in the resolution of the diffusion equation under these complexities. To address these challenges, we introduced the Finite Element Method (FEM). We elucidated the method's rationale, from the derivation of the weak form to the formulation of the global linear system. We then evaluated the method's accuracy against the exact solution, revealing a relative error of ±3–4‰ under the specified settings, which is an order of magnitude lower than that of LA-ICP-MS, thus demonstrating the robustness of the method. Following that, our two- and three-dimensional numerical experiments showcased FEM's adaptability in modeling species diffusion across arbitrary geometries and both Dirichlet and Neumann boundary conditions. Finally, the crystal's geometric effects on the ultimate elemental concentration were examined, revealing that they hold particular significance when the diffusion length is small. We conclude that the FEM surpasses the geometric limitations of minerals while simultaneously accommodating a variety of boundary conditions, thus offering significant potential for broad applications in the field.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012182","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822064","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":"An Assessment of Monazite Fission-Track Thermochronology as a Proxy for Low-Magnitude Cooling, Catalina-Rincon Metamorphic Core Complex, AZ, USA","authors":"Gilby Jepson,&nbsp;Barbara Carrapa,&nbsp;Sean Jones,&nbsp;Barry P. Kohn,&nbsp;Andrew J. W. Gleadow,&nbsp;Sarah W. M. George,&nbsp;Caden J. Howlett,&nbsp;Kerry Gallagher,&nbsp;Alex N. Frickenstein,&nbsp;George Gehrels,&nbsp;Antoine Triantafyllou","doi":"10.1029/2024GC011881","DOIUrl":"https://doi.org/10.1029/2024GC011881","url":null,"abstract":"<p>Conventional low-temperature thermochronology can resolve rock cooling over geological timescales (&gt;1 Myr) typically associated with ∼6–2 km of erosion, often induced by tectonic processes. Lower magnitude erosional events, however, produced by surface processes remain difficult to resolve. Here, we apply monazite fission-track (MFT) thermochronometry to the tectonically well-constrained Catalina-Rincon metamorphic core complex (MCC) to assess its ability to resolve low-temperature cooling in the upper-crust over ∼10⁶ years timescales. Established low-temperature thermochronology (apatite fission-track [AFT] and apatite and zircon [U-Th-Sm]/He) record timing of MCC and subsequent Basin and Range tectonic exhumation (26–20 Ma and 15–12 Ma, respectively). Monazite fission-track data were obtained from samples collected in two vertical elevation profiles. The eastern transect displays a Late Miocene—Pliocene age-elevation trend and implies a two-stage cooling history related to late-stage footwall uplift associated with Basin and Range normal faulting (∼7.5–5.1 Ma) and subsequent Pliocene—Pleistocene erosion (∼4.0–3.0 Ma). The northwestern transect data suggest a single period of rapid Pliocene—Pleistocene cooling (∼2.8–1.0 Ma). Thermal history modeling, however, fails to find a solution that satisfies the MFT annealing model with the AFT annealing and (U-Th-Sm)/He diffusion models. This suggests that the present MFT thermal annealing model does not account for all sources of annealing. We suggest that Pliocene—Pleistocene MFT ages may record a period of climate-enhanced erosion during a known phase of increased precipitation associated with the development of the North American Monsoon.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011881","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143821987","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":"Redox-State and Bioproductivity of the Glaciogenic Early Cryogenian Rapitan Iron Formation (Cranswick River, Canada): Constraints From Combined Cadmium—Chromium Isotopes","authors":"Robert Frei,&nbsp;Geoff Baldwin,&nbsp;Michael G. Babechuk,&nbsp;Balz S. Kamber,&nbsp;Elizabeth C. Turner","doi":"10.1029/2024GC012038","DOIUrl":"https://doi.org/10.1029/2024GC012038","url":null,"abstract":"<p>The Rapitan Group (Northwest Territories, Canada) includes banded iron formation (BIF), an unusual sediment type that is associated with late Neoproterozoic glaciations, in this case, the early Cryogenian Sturtian glaciation. New non-traditional stable isotope data from jasper and hematite iron formation (IF) from the Cranswick River area contribute new insights regarding water chemistry changes in the respective depositional basin during glacier advance and retreat. Cr isotope signatures are characterized by strongly positively fractionated δ⁵³Cr values (+0.68–1.47‰), attesting to strongly oxidized surface waters during the entire depositional episode. Relatively weakly fractionated δ¹¹⁴Cd isotope signatures (−0.02 to +0.28‰), and the absence of organic matter in the samples, indicate a low bioproductivity during BIF deposition. Detailed fluctuations over an intermittent glacier advance and retreat cycle recorded in the studied section, however, reveal an ephemeral increase in primary production (excursion to slightly elevated δ¹¹⁴Cd values) just after deposition of a diamictite layer, which agrees with corresponding elevated δ⁵³Cr values. This evidence attests to the sensitivity of the Cd-Cr double isotope tracer applied to BIFs to reconstruct changes in the surface waters of depositional basins and track climate changes that accompanied the glacial episodes. When compared to data from the younger (Marinoan/Ediacaran) Urucum BIF in Brazil, the Rapitan section differs by lack of negative Ce anomalies in its rare earth element patterns, implying that water column oxidation was not as strong during the early Cryogenian as compared to the Marinoan/Ediacaran glacial episodes.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143818559","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":"Continuous Subsidence of Dallol Volcano Caused by Magmatic, Hydrothermal, and Salt Dissolution Processes: Insights From InSAR Observations","authors":"Birhan A. Kebede,&nbsp;Carolina Pagli,&nbsp;Derek Keir,&nbsp;Freysteinn Sigmundsson,&nbsp;Alessandro La Rosa,&nbsp;Hua Wang,&nbsp;Elias Lewi,&nbsp;Snorri Gudbrandsson","doi":"10.1029/2024GC012048","DOIUrl":"https://doi.org/10.1029/2024GC012048","url":null,"abstract":"<p>The Dallol volcano on the axis of the Erta Ale ridge (Afar rift) offers an ideal opportunity to study the interaction between magmatic and hydrothermal processes. Volcanic activity in Dallol has developed in an area below sea level with a salt plain. Dallol has been actively deforming since InSAR measurements started in the area in 2004. However, the source of deformation under Dallol remains unclear. We present a new InSAR study of Dallol from 2014 to 2023 showing at least three concentric deformation signals of range increase consistent with subsidence with rates ranging 23–43 mm/yr in the satellite Line-of-Sight. The main subsidence occurs at Dallol volcano, and two smaller maxima occur at the Black Mountain and the Bubbling Pool areas to the south and southwest of Dallol, respectively. Our modeling indicates that the deformation is caused by contraction of three sill-shaped sources (Okada tensile dislocations) at depths ranging 0.6–1.5 km, each with a volume contraction in the range 1.8–5.5 × 10⁴ m³/yr. Time series analysis shows that the subsidence at Dallol volcano and Black Mountain was continuous and linear in time. Furthermore, an integrated observation of InSAR with the geology, resistivity image and seismic reflection of the area suggest that the 1.5 km deep source under Dallol is the cooling and contraction of a magma reservoir. At Black Mountain (1 km deep) and Bubbling Pool (0.6 km deep), the data suggest that subsidence is due to either a pressure decreases in the shallow hydrothermal system and/or salt dissolution.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809617","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 Did Westward Volcaniclastic Deposits Accumulate in the Deep Sea Following the January 2022 Eruption of Hunga Volcano?","authors":"Marcus Chaknova,&nbsp;Thomas Giachetti,&nbsp;Joali Paredes-Mariño,&nbsp;Adam Soule,&nbsp;Alexa R. Van Eaton,&nbsp;Roxanne Beinart,&nbsp;Martin Crundwell,&nbsp;Shane J. Cronin,&nbsp;Martin Jutzeler,&nbsp;Kristen E. Fauria,&nbsp;Michael A. Clare,&nbsp;Isobel A. Yeo,&nbsp;Shawn Arellano,&nbsp;Liam Kelly,&nbsp;Sally Watson,&nbsp;Rebecca Carey,&nbsp;Taaniela Kula,&nbsp;Craig M. Young","doi":"10.1029/2024GC011629","DOIUrl":"https://doi.org/10.1029/2024GC011629","url":null,"abstract":"<p>Most volcanic eruptions on Earth take place below the ocean surface and remain largely unobserved. Reconstruction of past submerged eruptions has thus primarily been based on the study of seafloor deposits. Rarely before the 15 January 2022 eruption of Hunga volcano (Kingdom of Tonga) have we been able to categorically link deep-sea deposits to a specific volcanic source. This eruption was the largest in the modern satellite era, producing a 58-km-tall plume, a 20-m high tsunami, and a pressure wave that propagated around the world. The eruption induced the fastest submarine density currents ever measured, which destroyed submarine telecommunication cables and traveled at least 85 km to the west to the neighboring Lau Basin. Here we report findings from a series of remotely operated vehicle dives conducted 4 months after the eruption along the Eastern Lau Spreading Center-Valu Fa Ridge. Hunga-sourced volcaniclastic deposits 7–150 cm in thickness were found at nine sites, and collected. Study of the internal structure, grain size, componentry, glass chemistry, and microfossil assemblages of the cores show that these deposits are the distal portions of at least two ∼100-km-runout submarine density currents. We identify distinct physical characteristics of entrained microfossils that demonstrate the dynamics and pathways of the density currents. Microfossil evidence suggests that even the distal parts of the currents were erosive, remobilizing microfossil-concentrated sediments across the Lau Basin. Remobilization by volcaniclastic submarine density currents may thus play a greater role in carbon transport into deep sea basins than previously thought.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011629","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809613","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":"Analysis of Paleointensity Results Under Different Interpretation Approaches: A Case Study on the Korkhi Volcanic Sequence (Lesser Caucasus, Georgia)","authors":"Elisa M. Sánchez-Moreno,&nbsp;Manuel Calvo-Rathert,&nbsp;Avto Goguitchaichvili,&nbsp;George T. Vashakidze,&nbsp;Lisa Tauxe,&nbsp;Pierre Camps,&nbsp;Juan Morales-Contreras,&nbsp;Vladimir A. Lebedev,&nbsp;Néstor Vegas,&nbsp;Nayeli Pérez-Rodriguez,&nbsp;Ketino Gabarashvili","doi":"10.1029/2023GC011382","DOIUrl":"https://doi.org/10.1029/2023GC011382","url":null,"abstract":"<p>In this study we focus on the investigation of the absolute intensity records of two volcanic subsequences, aiming to enrich the global paleointensity database for the last 5 Ma, which currently shows important dispersion. We present new absolute paleointensities obtained from the Plio-Pleistocene volcanic sequence of Korkhi (Djavakheti Highland, Georgia) (41°27′31″N, 43°27′55″E). Korkhi is divided into two lava flow subsequences dated at 3.11 ± 0.20 Ma and 1.85 ± 0.08 Ma. Paleomagnetic directions previously published (Sánchez-Moreno et al., 2018, https://doi.org/10.1029/2017GC007358) show a normal polarity in the lower Korkhi subsequence and a reverse-to-intermediate polarity in the upper Korkhi subsequence. The new paleointensity determinations are obtained through two different Thellier-type protocols (Thellier-Thellier and IZZI) and the corrected multispecimen method. We utilize different selection criteria and interpretation approaches (TTB, CCRIT, BiCEP and multimethod), and we make a critical evaluation on their application on complex magnetic behaviors, such as often found in volcanic rocks. Finally, we obtained a paleointensity of 70 μT in upper Korkhi and 14 paleointensities in lower Korkhi that vary between 5.2 and 37.2 μT. These results agree with a recently proposed non-Geocentric Axial Dipole (GAD) hypothesis for the last ∼1.5 Ma (Cych et al., 2023, https://doi.org/10.1029/2023JB026492), and with low field strength for the 3–4 Ma.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC011382","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786975","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":"Linking Cenozoic Magmatism in the North-Central Tibetan Plateau With Plateau Growth","authors":"Peng Guo,&nbsp;Ting Yang,&nbsp;Wei-Qiang Ji","doi":"10.1029/2024GC011898","DOIUrl":"https://doi.org/10.1029/2024GC011898","url":null,"abstract":"<p>Accurate reconstruction of paleo-crustal and lithospheric thicknesses is crucial for understanding the deep geodynamic processes driving the uplift and growth of the Tibetan Plateau (TP) and their association with Cenozoic magmatism. We reconstruct the Cenozoic crustal thickness evolution of the north-central TP using a machine learning model for intermediate to felsic rocks, and estimate the lithospheric thickness based on geobarometers for mafic magmas. We find that the northern Qiangtang terrane (QT) underwent crustal thickening during the late Cretaceous-early Eocene, with the crust thickening to 60.2 ± 4.8 km by 45 Ma, while the lithospheric thickness was only 60.9 ± 4.5 km. This suggests wholesale delamination of the lithospheric mantle shortly before ∼45 Ma, explaining the formation of high MgO adakitic rocks and the uplift of the Tanggula Mountain to ≥5 km. To the south, the southern QT crust thickened by ∼16 km during the late Eocene-early Oligocene, contributing to ≥2 km uplift of the valley south of the Tanggula Mountain. To the north the Songpan-Ganzi terrane (SGT) had a crustal thickness of 60.6 ± 3.6 km at ∼18 Ma and underwent ∼25 km of lithospheric thinning during ∼16–13 Ma. This process contributed to the formation of Miocene shoshonitic mafic rocks and adakitic rocks in the SGT, and the uplift of the Hoh-Xil Basin to its present elevation. The recovered crustal and lithospheric thickness evolution demonstrates that progressive removal of the lower lithosphere following crustal shortening is the main driver for the uplift and magmatism of different regions in the TP.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011898","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143793722","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":"Construction of Ultraslow-Spreading Oceanic Crust: New Insights on Volcanic Processes and Deposits From High-Resolution Mapping at the Mohns Ridge","authors":"Håvard Hallås Stubseid,&nbsp;Anders Bjerga,&nbsp;Ryan Portner,&nbsp;Haflidi Haflidason,&nbsp;Rolf Birger Pedersen","doi":"10.1029/2024GC012141","DOIUrl":"https://doi.org/10.1029/2024GC012141","url":null,"abstract":"<p>The volcanic activity at ultraslow-spreading ridges is less understood compared with that at faster-spreading ridges. Studies of year-to-year changes along the faster-spreading ridges have provided important information regarding the size and frequency of eruptions. However, ultraslow-spreading ridges produce less frequent eruptions, limiting the possibility to study short-term changes in the seafloor morphology to understand longer-term volcanic processes. Therefore, a different approach is needed to estimate the size and frequency of volcanic eruptions at the slowest spreading ridges. Here, we use meter-scale bathymetric maps and backscatter data together with visual observations and geochronology of both basalts and sediments to study the construction of three axial volcanic ridges (AVRs) along the northern half of the ultraslow-spreading Mohns Ridge. Our study finds that most eruptions produce low-effusion rate pillow lavas (82% of the volcanic terrain). We define “lava flow units” as mappable building-blocks of the ARVs, each with a coherent morphology, which may be emplaced during multiple eruptions, but we envision over a relatively short time span (years to decades). These units vary in size from individual hummocks to larger edifices (0.42 × 10⁶ to 38 × 10⁶ m³). Moreover, we estimate the eruptive frequencies per AVR to be on a hundred-year scale. These spatial-temporal constraints in AVR volcanism offer insight into long-term magma flux and spatial focusing along magma-starved ultraslow spreading ridge systems.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012141","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143786848","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":"Tracing the Contribution of Abiotic Methane in Deep Natural Gases From the Songliao Basin, China Using Bulk Isotopes and Methane Clumped Isotopologue 12CH2D2","authors":"Jiacheng Li,&nbsp;Qingmei Liu,&nbsp;Wenmin Jiang,&nbsp;Yun Li,&nbsp;Yanhua Shuai,&nbsp;Yongqiang Xiong","doi":"10.1029/2024GC011705","DOIUrl":"https://doi.org/10.1029/2024GC011705","url":null,"abstract":"<p>The identification and evaluation of abiotic methane remain an active research area due to uncertainties in traditional indicators that may lead to “false-positive” detections. As an emerging isotopic tool, methane clumped isotope can provide novel information about the generation and post-generation processes of methane gases. Using six deep natural gas samples from the Songliao Basin, we explored the potential of clumped isotopes in identifying abiotic methane. The results indicate that the Δ¹³CH₃D values of all samples are consistent with the thermodynamic equilibrium values at the inferred formation temperatures, whereas the Δ¹²CH₂D₂ values show small but detectable deficits (1∼6‰) relative to equilibrium. This particular non-equilibrium clumped isotopic signature of natural gas from the Songliao Basin is similar to the clumped isotopic signature of abiotic methane predicted by an isotopologue-specific kinetic model, suggesting a possible contribution of abiotic methane in the studied natural gases. However, we found that the mixing of abiotic and thermogenic gases could not fully explain the isotope data of all the samples. The proportion of abiotic gas calculated based on clumped isotopes would be underestimated because methane isotopic bond re-ordering at the late burial temperatures partially erases the disequilibrium signatures inherited from the original mixtures. The carbon isotopic reversals in C₁–C₃ of the samples provide additional constraint for evaluating the contribution of abiotic gas. Therefore, the coupling of intra-molecular clumped isotope and inter–molecular carbon isotope signatures may be a more robust approach for identifying abiotic methane, which can help us to quantitatively evaluate abiotic methane in petroleum systems.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011705","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778426","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}