Geochemistry Geophysics Geosystems最新文献

{"title":"Neogene Hydrothermal Fe- and Mn-Oxide Mineralization of Paleozoic Continental Rocks, Amerasia Basin, Arctic Ocean","authors":"James R. Hein,&nbsp;Kira Mizell,&nbsp;Amy Gartman","doi":"10.1029/2023GC010996","DOIUrl":"https://doi.org/10.1029/2023GC010996","url":null,"abstract":"<p>Rocks dredged from water depths of 1,605, 2,500, 3,300, and 3,400 m in the Arctic Ocean included Paleozoic continental rocks pervasively mineralized during the Neogene by hydrothermal Fe and Mn oxides. Samples were recovered in three dredge hauls from the Chukchi Borderland and one from Mendeleev Ridge north of Alaska and eastern Siberia, respectively. Many of the rocks were so pervasively altered that the protolith could not be identified, while others had volcanic, plutonic, and metamorphic protoliths. The mineralized rocks were cemented and partly to wholly replaced by the hydrothermal oxides. The Amerasia Basin, where the Chukchi Borderland and Mendeleev Ridge occur, supports a series of faults and fractures that serve as major zones of crustal weakness. We propose that the stratabound hydrothermal deposits formed through the flux of hydrothermal fluids along Paleozoic and Mesozoic faults related to block faulting along a rifted margin during minor episodes of Neogene tectonism and were later exposed at the seafloor through slumping or other gravity processes. Tectonically driven hydrothermal circulation most likely facilitated the pervasive mineralization along fault surfaces via frictional heating, hydrofracturing brecciation, and low- to moderate temperature Fe- and Mn-rich hydrothermal fluids, which mineralized the crushed, altered, and brecciated rocks.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GC010996","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142596268","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":"Matrix Corrected SIMS In Situ Oxygen Isotope Analyses of Marine Shell Aragonite for High Resolution Seawater Temperature Reconstructions","authors":"Oliver M. Medd,&nbsp;Laura M. Otter,&nbsp;Ian S. Williams,&nbsp;Richard A. Stern,&nbsp;Michael W. Förster,&nbsp;Stephen M. Eggins,&nbsp;Laura Rodriguez-Sanz,&nbsp;Nerilie J. Abram,&nbsp;Miaohong He,&nbsp;Michael J. Ellwood,&nbsp;Jessica A. Hargreaves,&nbsp;Stewart J. Fallon,&nbsp;Brett M. Knowles","doi":"10.1029/2024GC011577","DOIUrl":"https://doi.org/10.1029/2024GC011577","url":null,"abstract":"<p>Marine shells incorporate oxygen isotope signatures during growth, creating valuable records of seawater temperature and marine oxygen isotopic compositions. Secondary ion mass spectrometry (SIMS) measures these compositions in situ at finer length-scales than traditional stable isotope analyses. However, determining oxygen isotope ratios in aragonite, the most common shell mineral, is hampered by a lack of ideal reference materials, limiting the accuracy of SIMS-based seawater temperature reconstructions. Here, we tested the capability of SIMS to produce seawater temperature reconstructions despite the matrix calibration challenges associated with aragonite. We cultured <i>Anadara trapezia</i> bivalves at four controlled seawater temperatures (13–28°C) and used strontium labeling to mark the start of the temperature-controlled shell increment, allowing for more spatially precise SIMS analysis. An improved matrix calibration was developed to ensure more accurate bio-aragonite analyses that addressed matrix differences between the pure abiotic reference materials and the bio-aragonite samples with intricate mineral-organic architectures and distinct minor and trace element compositions. We regressed SIMS-IRMS biases of abiotic and biogenic aragonites that account for their systematic differences in major, minor, and trace elements, allowing for more accurate SIMS analyses of the temperature-controlled shell increment. The thorough matrix calibration allowed us to provide a SIMS-based seawater-corrected oxygen isotope thermometer of T(°C) = 23.05 ± 0.36 − 4.48 · (δ¹⁸O_aragonite [‰ VPDB] − δ¹⁸O_seawater [‰ VSMOW] ± 0.25) and 10³ln<i>α</i>_{aragonite-seawater} = (17.78 ± 0.88) · 10³/T (K) − (29.44 ± 2.40) that agrees with existing aragonitic IRMS-based thermometer relationships and improves the applicability of SIMS-based paleo-environmental reconstructions of marine bio-aragonites.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011577","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142596319","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":"Investigating the Effect of Lithosphere Thickness and Viscosity on Mantle Dynamics Throughout the Supercontinent Cycle","authors":"A. Plimmer,&nbsp;J. H. Davies,&nbsp;J. Panton","doi":"10.1029/2024GC011688","DOIUrl":"https://doi.org/10.1029/2024GC011688","url":null,"abstract":"<p>The relationship between the lithosphere and the mantle during the supercontinent cycle is complex and poorly constrained. The processes which drive dispersal are often simplified to two end members: slab pull and plume push. We aim to explore how lithosphere thickness and viscosity during supercontinent assembly may affect the interaction of deep mantle structures throughout the supercontinent cycle. We consider supercontinental lithosphere structure as one of many potential processes which may affect the evolution of upwellings and downwellings and therefore systematically vary the properties of continental and cratonic lithosphere, respectively within our 3D spherical simulations. The viscosity and thickness of the lithosphere alters the dip and trajectory of downwelling material beneath the supercontinent as it assembles. Focusing on Pangea, we observe that plumes evolve and are swept beneath the center of the supercontinent by circum-continental subduction. The proximity of these upwelling and downwelling structures beneath the supercontinent interior varies with lithosphere thickness and viscosity. Where slabs impinge on the top of an evolving plume head (when continental and cratonic lithosphere are thick and viscous in our simulations), the cold slabs can reduce the magnitude of an evolving plume. Conversely, when the continental lithosphere is thin and weak in our simulations, slab dips shallow in the upper mantle and descend adjacent to the evolving plume, sweeping it laterally near the core-mantle boundary. These contrasting evolutions alter the magnitude of the thermal anomaly and the degree to which the plume can thin the lithosphere prior to breakup.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011688","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561596","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":"Solid Earth Carbon Degassing and Sequestration Since 1 Billion Years Ago","authors":"R. Dietmar Müller,&nbsp;Adriana Dutkiewicz,&nbsp;Sabin Zahirovic,&nbsp;Andrew S. Merdith,&nbsp;Christopher R. Scotese,&nbsp;Benjamin J. W. Mills,&nbsp;Lauren Ilano,&nbsp;Ben Mather","doi":"10.1029/2024GC011713","DOIUrl":"https://doi.org/10.1029/2024GC011713","url":null,"abstract":"<p>Solid Earth CO₂ outgassing, driven by plate tectonic processes, is a key driver of carbon cycle models. However, the magnitudes and variations in outgassing are poorly constrained in deep-time. We assess plate tectonic carbon emissions and sequestration by coupling a plate tectonic model with reconstructions of oceanic plate carbon reservoirs and a thermodynamic model to quantify outfluxes from slabs and continental arcs over 1 billion years. In the early Neoproterozoic, our model predicts a peak in crustal production and net outgassing from 840 to 780 Ma that corresponds to a contemporaneous pulse in large igneous province eruptions. The Sturtian and Marinoan glaciations (717–635 Ma) correspond to a low in mid-ocean ridge outgassing, while the following Ediacaran global warming coincides with a rise in net atmospheric carbon influx, driven by an increase in plate boundary and rift length. The Cambrian, Silurian/Devonian and Triassic Jurassic hothouse climates are synchronous with a reduction in carbon sequestration flux into oceanic plates, increasing net outgassing. In contrast, the Early Cretaceous hothouse climate is accompanied by a pronounced increase in mid-ocean ridge outgassing. Both the Early Ordovician cooling and the late Paleozoic ice ages coincide with a significant decrease in net atmospheric outgassing, driven by an increase in carbon sequestration. The late Cenozoic glaciation is associated with a long-term decrease in mid-ocean ridge and rift degassing, and a pronounced increase in carbon flux into pelagic carbonate sediments. Our tectono-thermodynamic carbon cycle model provides a new foundation for future long-term climate and geochemical cycling models.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011713","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561647","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":"Rhenium Isotopes Record Oxidative Weathering Intensity in Sedimentary Rocks","authors":"A. J. Dickson,&nbsp;R. G. Hilton,&nbsp;J. Prytulak,&nbsp;D. Minisini,&nbsp;J. S. Eldrett,&nbsp;M. Dellinger,&nbsp;M. Stow,&nbsp;W. Wang","doi":"10.1029/2024GC011795","DOIUrl":"https://doi.org/10.1029/2024GC011795","url":null,"abstract":"<p>Oxidative weathering of organic carbon in sedimentary rocks is a major source of CO₂ to the atmosphere over geological timescales, but the size of this emission pathway in Earth's past has not been directly quantified due to a lack of available proxy approaches. We have measured the rhenium isotope composition of organic-rich rocks sampled from unweathered drill cores and weathered outcrops in south Texas, whose stratigraphic successions can be tightly correlated. Oxidative weathering of more than 90% of the organic carbon and ∼85% of the rhenium is accompanied by a shift to lower rhenium isotope compositions in the weathered outcrops. The calculated isotope composition of rhenium weathered from the initial bedrock for individual samples varies systematically by ∼0.7‰ with different fractions of rhenium loss. This variation can be empirically modeled with isotope fractionation factors of <i>α</i> = 1.0002–1.0008. Our results indicate that the isotope composition of rhenium delivered to the oceans can be altered by weathering intensity of rock organic matter and that the rhenium isotope composition of seawater is sensitive to past oxidative weathering and associated CO₂ emissions.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011795","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525642","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":"Biogeochemical Reconstruction of Authigenic Carbonate Deposits at Methane Seep Site off Krishna-Godavari (K-G) Basin, Bay of Bengal","authors":"S. P. K. Pillutla,&nbsp;A. Peketi,&nbsp;A. Mazumdar,&nbsp;Mohd. Sadique,&nbsp;K. Sivan,&nbsp;Anjali Zatale,&nbsp;S. Mishra,&nbsp;Swati Verma","doi":"10.1029/2024GC011801","DOIUrl":"https://doi.org/10.1029/2024GC011801","url":null,"abstract":"<p>Active and relic marine methane-seep sites are widely distributed globally and are distinguished by distinctive geology, biogeochemistry, and ecosystems. The discovery of methane-seep sites in the Krishna-Godavari (K-G) basin has created exciting new opportunities for methane-seep research in the Bay of Bengal. In this study, we document the occurrence of authigenic carbonates, including micro-crystalline aragonite crust (arg-crusts) admixed with chemosynthetic shells and high-magnesium carbonate tubular structures (HMC-tube), from the methane-seep site SSD-045/4 in the K-G basin. The δ¹³C values of HMC-tubes (−54.5 to −46.2‰) and arg-crusts (−57.6 to −34.8‰) indicate biogenic methane as the likely carbon source. Enhanced porewater alkalinity driving carbonate precipitation may be attributed to microbial-mediated SO₄²⁻-AOM processes. Additionally, δ¹³C values (−35.2 ± 8‰) of the residual organic matter within the carbonates suggest a contribution of methanotrophic bacterial biomass. The δ¹⁸O_carb values of HMC and aragonite indicate methane hydrate degassing and crystallization pathways, respectively. Pelloid-filled burrows suggest the reworking of shallow HMC deposit by burrowing organisms, whereas the polyphase cementations (aragonite and HMC) within burrows indicate early and burial diagenetic pathways. The wide range in ΣLREE/ΣHREE ratios and Ce_anom values in arg-crusts reflect micro-spatial variations in redox conditions, likely due to cementation occurring in both open and closed diagenetic systems. In contrast, more constrained Ce_anom values and ΣLREE/ΣHREE ratios in HMC tubes suggest persistent sulfidic conditions. Overall, these findings provide insights into the pathways of carbonate formation at the K-G basin methane-seep site, highlighting the complex interplay of microbial processes, fluid dynamics, and diagenetic alterations.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011801","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525613","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":"Identifying Recycled Materials Using Mo Isotopes in Intraplate Alkali Basalts From the Southeastern Margin of Tibetan Plateau","authors":"Dongjing Xu,&nbsp;Yue Qi,&nbsp;Qiang Wang,&nbsp;Jie Li,&nbsp;Derek A. Wyman,&nbsp;Andrew C. Kerr,&nbsp;Xiuzheng Zhang,&nbsp;Peina Guo","doi":"10.1029/2024GC011750","DOIUrl":"https://doi.org/10.1029/2024GC011750","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Mantle heterogeneity in lithology and geochemistry is often attributed to recycled subducted materials. While distinct mantle end-members are identified by radiogenic isotopes, the specific recycled materials contributing to this heterogeneity remain debated. This study presents Mo-Sr-Nd-Pb isotopic data for OIB-like alkali basalts from the Maguan area in the southeastern Tibetan Plateau, focusing on slab inputs' role in mantle heterogeneity. The Miocene (ca. 13 Ma) Maguan alkali basalts are divided into two types based on petrographic and geochemical characteristics, showing similar Sr-Nd-Pb isotopic signatures but different Mo isotopic compositions. Type I basalts exhibit a wide δ^98/95Mo range (−0.31‰ to −1.03‰, average −0.47‰ ± 0.06‰, 2SD = 0.40‰, <i>n</i> = 13), while type II basalts have heavy and constant δ^98/95Mo values (−0.11‰ to −0.17‰, average −0.14‰ ± 0.01‰, 2SD = 0.05‰, <i>n</i> = 6). The unique low δ^98/95Mo value (−1.03‰) in type I basalts is among the lowest reported in OIB-like continental basalts. Type I basalts likely originate from an enriched asthenospheric mantle metasomatized by melts from recycled dehydrated oceanic crust and sediments, whereas type II basalts are derived from partial melting of an enriched asthenospheric mantle metasomatized by melts from recycled serpentinized peridotites. The residual Tethys oceanic slabs in the deep mantle significantly contribute to the mantle source of the Maguan basalts. The formation of Maguan Miocene magmas may be linked to mantle upwelling induced by the subduction of the West Burma plate. This study highlights the Mo isotopic system's utility in tracing complex slab fluxes generating mantle geochemical heterogeneity.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011750","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525494","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":"Paleomagnetic Secular Variations in North Greenland Around 81°N Over the Last 6,000 Years","authors":"Juliette Girard,&nbsp;Brendan T. Reilly,&nbsp;Guillaume St-Onge,&nbsp;France Lagroix,&nbsp;Jean-Carlos Montero-Serrano,&nbsp;Joesph S. Stoner,&nbsp;Anne E. Jennings","doi":"10.1029/2024GC011620","DOIUrl":"https://doi.org/10.1029/2024GC011620","url":null,"abstract":"<p>We investigate full vector paleomagnetic changes recorded in high-resolution sediments of Petermann Fjord, North Greenland, deposited over the last 6 kyr, in the context of the recent rapid changes in the geomagnetic field. A Paleomagnetic Secular Variation (PSV) stack (inclination, declination, and relative paleointensity) was reconstructed using four marine sediment cores with an independent age model constrained by seven radiocarbon ages. Magnetic investigations demonstrate that the paleomagnetic signal is carried by low coercivity ferrimagnetic minerals and is well reproduced in all cores, attesting to the quality and reliability of the paleomagnetic recording of these sediments. This signal is broadly consistent in directional changes with distant records in North America and the northern North Atlantic at centennial and millennial timescales, and has millennial scale intensity variations that are consistent with model predictions. The offset between a magnetization age determined through comparison with a northern North Atlantic PSV reference curve, GREENICE, and the radiocarbon age model indicates either a reasonable lock-in depth of magnetization (∼11 cm from the coretop) or centennial-scale reservoir age variation through time in the fjord. Reconstructed virtual geomagnetic pole (VGP) migration for the last 6 kyr shows that the recent migration of the magnetic North Pole is consistent with secular paleomagnetic variations on geologic timescales. Our results suggest that magnetic field intensity variations (temporal and spatial) are linked to magnetic flux lobe dynamics and influence the VGP migration.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011620","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525493","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":"Assessing the Precision and Accuracy of Foraminifera Elemental Analysis at Low Ratios","authors":"Wanyi Lu,&nbsp;Weifu Guo,&nbsp;Delia W. Oppo","doi":"10.1029/2024GC011560","DOIUrl":"https://doi.org/10.1029/2024GC011560","url":null,"abstract":"<p>The minor and trace element compositions of biogenic carbonates such as foraminifera are important tools in paleoceanography research. However, most studies have focused primarily on samples with element to calcium (El/Ca) ratios higher than the El/Ca range often found in benthic foraminifera. Here, we systematically assess the precision and accuracy of foraminifera elemental analysis across a wide range of El/Ca especially at relatively low ratios, using a method on a Thermo Scientific iCAP Qc quadrupole Inductively Coupled Plasma Mass Spectrometer (ICP-MS). We focus on two benthic foraminifera species, <i>Hoeglundina elegans</i> and <i>Cibicidoides pachyderma</i>, and prepared a suite of solution standards based on their typical El/Ca ranges to correct for signal drift and matrix effects during ICP-MS analysis and to determine analytical precision. We observe comparable precisions with published studies at high El/Ca, and higher relative standard deviations for each element at lower El/Ca, as expected from counting statistics. The overall long-term analytical precision (2<i>σ</i>) of the <i>H. elegans</i>-like consistency standard solutions was 6.5%, 4.6%, 5.0%, for Li/Ca, Mg/Ca, Mg/Li, and 6.4%, 10.0%, 4.2% for B/Ca, Cd/Ca, Sr/Ca. The precision for <i>H. elegans</i>-like Mg/Li is equivalent to a temperature uncertainty of 0.5–1.1°C. Measurement precisions were also assessed based on three international standards (one solution and two powder standards) and replicate measurements of <i>H. elegans</i> and <i>C. pachyderma</i> samples. We provide file templates and program scripts that can be used to design calibration and consistency standards, prepare run sequences, and convert the raw ICP-MS data into molar ratios.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011560","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525537","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":"Radiogenic Strontium- and Uranium-Isotope Tracers of Water-Rock Interactions and Hydrothermal Flow in the Upper Geyser Basin, Yellowstone Plateau Volcanic Field, USA","authors":"James B. Paces,&nbsp;Shaul Hurwitz,&nbsp;Lauren N. Harrison,&nbsp;Jacob B. Lowenstern,&nbsp;R. Blaine McCleskey","doi":"10.1029/2024GC011729","DOIUrl":"https://doi.org/10.1029/2024GC011729","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Natural radiogenic isotopes (primarily ⁸⁷Sr/⁸⁶Sr) from hot springs in the Upper Geyser Basin of the Yellowstone Plateau volcanic field and associated rocks were used to evaluate groundwater flow patterns, water-rock reactions, and the extent of mixing between various groundwater sources. Thermal waters have very low uranium concentrations and ²³⁴U/²³⁸U activity ratios near 1.0, which limit their utility as tracers in this reducing setting. Thermal waters have higher Sr concentrations (&lt;22 ng/g) and a wide range of ⁸⁷Sr/⁸⁶Sr values that vary both temporally at individual discharge sites and between adjacent springs, indicating that conduits tap different subsurface reservoirs to varying degrees. Sr from local rhyolites have ⁸⁷Sr/⁸⁶Sr compositions that bound the range of values observed in groundwater throughout the basin. Non-boiling springs on the west flank of the basin discharge water with low ⁸⁷Sr/⁸⁶Sr consistent with flow through young volcanic rocks exposed at the surface. Boiling springs in the central basin have higher ⁸⁷Sr/⁸⁶Sr values reflecting interactions with older, more radiogenic volcanic rocks. Variability in upwelling thermal waters requires mixing with a low ⁸⁷Sr/⁸⁶Sr component derived from young lava or glacial sediments, or more likely, from deeper sources of hot groundwater circulating through buried Lava Creek Tuff having intermediate ⁸⁷Sr/⁸⁶Sr. Isotope data constrain basin-wide output of thermal water to 110–140 kg·s⁻¹. Results underscore the utility of radiogenic Sr isotopes as valuable tracers of hydrothermal flow patterns and improve the understanding of temperature-dependent water-rock reactions in one of the largest continental hydrothermal systems on Earth.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011729","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525492","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}