Geochemistry Geophysics Geosystems最新文献_第5页

An Oceanic Plateau Induced Subduction Zone Jump From Proto- to Paleo-Tethys in East Kunlun, Northern Tibetan Plateau 青藏高原北部东昆仑地区原-古特提斯洋高原诱导俯冲带跃迁

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-05 DOI: 10.1029/2025GC012211

Rutao Zang, Yunpeng Dong, Dazhi Jiang, Dengfeng He, Shengsi Sun, Bo Hui, Bin Zhang

{"title":"An Oceanic Plateau Induced Subduction Zone Jump From Proto- to Paleo-Tethys in East Kunlun, Northern Tibetan Plateau","authors":"Rutao Zang, Yunpeng Dong, Dazhi Jiang, Dengfeng He, Shengsi Sun, Bo Hui, Bin Zhang","doi":"10.1029/2025GC012211","DOIUrl":"https://doi.org/10.1029/2025GC012211","url":null,"abstract":"The relationship between the Proto-Tethys and Paleo-Tethys is still debated. Some researchers believe that the Paleo-Tethys opened after the Proto-Tethys closed, while others argue that they are the same ocean with two stages of subduction. We present field geology, geochemical, and geochronological data to support the latter interpretation. We identified a typical oceanic plateau remnant in the East Kunlun Orogenic Belt, northern Tibetan Plateau. The remnant preserves voluminous pillow basalts overlain by limestones and breccias. The pillow basalts are characterized by slight enrichment of LILEs and HSFEs, which are similar to those of modern oceanic plateaus and were derived from 15% to 30% melting of a spinel lherzolite mantle source at a high potential temperature (±1,556°C) suggesting a mantle plume origin. The formation age of the oceanic plateau is determined by zircon U-Pb dating to be 430 ± 3 and 428 ± 3 Ma. We suggest that the oceanic plateau jammed the subduction of the Proto-Tethys and led the subduction zone to jump to a new location, which has been attributed to the subduction of the Paleo-Tethys. This finding also explains the absence of magmatic activities in this region from 370 to 290 Ma.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012211","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558177","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}

引用次数: 0

K-Metasomatic Weakening of Oceanic Crust at Shallow Subduction Depths: Evidence From the Rodeo Cove Thrust Zone, Marin Headlands, California 浅俯冲深度洋壳的k -交代弱化：来自加利福尼亚马林海岬Rodeo湾冲断带的证据

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-05 DOI: 10.1029/2025GC012221

Benjamin D. Belzer, Melodie E. French, Noah J. Phillips

{"title":"K-Metasomatic Weakening of Oceanic Crust at Shallow Subduction Depths: Evidence From the Rodeo Cove Thrust Zone, Marin Headlands, California","authors":"Benjamin D. Belzer, Melodie E. French, Noah J. Phillips","doi":"10.1029/2025GC012221","DOIUrl":"https://doi.org/10.1029/2025GC012221","url":null,"abstract":"Studies of exhumed subduction shear zones indicate that metamorphism and metasomatism of the oceanic lithosphere influence the composition, structure, and rheology of megathrust faults, particularly deep along the plate boundary (>30 km). However, less is known about the effects that fluid-mediated chemical reactions have on the rheological evolution of oceanic crust at shallower depths, which may control diverse modes of fault slip and down-stepping of the plate boundary into oceanic crust. Here, we present a structural and geochemical study of fault rocks from the Rodeo Cove thrust zone (RCT) in California to examine feedbacks between deformation and metasomatism of oceanic crust in a shallow subduction thrust environment (<15 km). At the RCT, deformation is accommodated by a dense network of reddish and greenish cataclasites, which surround altered basalt blocks containing abundant calcite veins and cement. Electron microprobe analyses show that the altered basalt is primarily composed of clinopyroxene, albite, chlorite, and pumpellyite, whereas the cataclasite is dominated by ferroaluminoceladonite (K- and Fe-rich mica) and iron-oxyhydroxides interlayered with well-crystallized sheets of aluminoceladonite. Our findings suggest that subduction-related faulting and cataclasis increased permeability within the basalt-hosted shear zone, promoting extensive K-metasomatism, first by oxidizing seawater and later by hydrothermal fluids sourced from subducted sediment and/or altered oceanic crust at greater depths. Moreover, contrasting deformation mechanisms between the less altered basalt and strongly K-metasomatized cataclasite, combined with their constitutive properties quantified from deformation experiments, indicate that K-metasomatism significantly decreased the frictional strength of oceanic crust causing strain to localize in the RCT.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012221","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564130","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}

引用次数: 0

Eoarchean–Paleoproterozoic Tectonothermal History of the Acasta Gneiss Complex Constrained by Titanite and Apatite Petrochronology 太古宙-古元古代阿卡斯塔片麻岩杂岩的构造热演化史——受钛矿和磷灰石岩石年代学约束

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-05 DOI: 10.1029/2025GC012294

Omar Khalil Droubi, Ann M. Bauer, Chloë Bonamici, William O. Nachlas, Joshua M. Garber, Michael J. Tappa, Jesse R. Reimink

{"title":"Eoarchean–Paleoproterozoic Tectonothermal History of the Acasta Gneiss Complex Constrained by Titanite and Apatite Petrochronology","authors":"Omar Khalil Droubi, Ann M. Bauer, Chloë Bonamici, William O. Nachlas, Joshua M. Garber, Michael J. Tappa, Jesse R. Reimink","doi":"10.1029/2025GC012294","DOIUrl":"https://doi.org/10.1029/2025GC012294","url":null,"abstract":"Deciphering Earth's earliest geodynamic processes requires temporally constrained chemical and structural data from rare exposures of ancient rocks. One of the most well-studied of these exposures is the Acasta Gneiss Complex (AGC) in the Northwest Territories, Canada, which contains the oldest known felsic rocks on Earth. Like other Archean terranes, the AGC has experienced billions of years of magmatism, metamorphism, and deformation, which make it difficult to tie chemical and structural information to specific events. To construct a reliable tectonothermal history, U-Th-Pb isotope and trace-element data from titanite and apatite were collected from two mafic amphibolites and four felsic-intermediate gneisses along a regional traverse through the AGC. The U-Th-Pb isotope data are augmented by petrography, backscattered electron and X-ray element maps, and trace-element compositions to better contextualize the polymetamorphic history preserved in these phases. Titanite records multiple metamorphic stages from ≥3.6 to 1.9 Ga, whereas apatite only preserves 1.9 Ga metamorphism. The ubiquity of ∼2.9 Ga titanite growth at amphibolite-facies or higher temperatures suggests widespread metamorphism in response to early tectonism. Partial to complete recrystallization of titanite and apatite at ∼1.9 Ga in the AGC is coeval with metamorphism during the Calderian orogeny. The preservation of Archean titanite in most samples suggests that the influence of the Calderian orogeny was not pervasive across the AGC. Our accessory phase petrochronologic data present a more complete geologic history for the AGC and inform models for early Earth geodynamics, formation of cratons, and the evolution of tectonics in the Slave craton.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012294","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558185","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}

引用次数: 0

The Systematics of Stable Hydrogen (δ2H) and Oxygen (δ18O) Isotopes and Tritium (3H) in the Hydrothermal System of the Yellowstone Plateau Volcanic Field, USA 美国黄石高原火山田热液系统中稳定氢（δ2H）、氧（δ18O）和氚（3H）同位素的分系统

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-04 DOI: 10.1029/2025GC012230

Shaul Hurwitz, R. Blaine McCleskey, Bryant C. Jurgens, Jacob B. Lowenstern, Laura Clor, Andrew G. Hunt

{"title":"The Systematics of Stable Hydrogen (δ2H) and Oxygen (δ18O) Isotopes and Tritium (3H) in the Hydrothermal System of the Yellowstone Plateau Volcanic Field, USA","authors":"Shaul Hurwitz, R. Blaine McCleskey, Bryant C. Jurgens, Jacob B. Lowenstern, Laura Clor, Andrew G. Hunt","doi":"10.1029/2025GC012230","DOIUrl":"https://doi.org/10.1029/2025GC012230","url":null,"abstract":"To improve our understanding of hydrothermal activity on the Yellowstone Plateau volcanic field, we collected and analyzed a large data set of δ2H, δ18O, and the 3H concentrations of circum-neutral and alkaline waters. We find that (a) hot springs are fed by recharge throughout the volcanic plateau, likely focused through fractured, permeable tuff units. Previous work had stressed the need for light δ2H water recharge restricted to the northern part of the plateau or recharge during past cold periods. However, new data from the Y-7 drill hole suggests that recharge is not restricted to a certain area or a cold period. (b) δ18O values of thermal waters in the geyser basins are shifted from the global meteoric water line by temperature-dependent water-rock reactions with higher subsurface temperatures resulting in a greater shift. (c) Large temporal variations in the isotopic composition of meteoric water recharge and small temporal variability in the isotopic composition of hot spring discharge implies that the volume of groundwater in, and around the Yellowstone caldera is substantially larger than the volume of annual water recharge. (d) Hot springs discharged through different rhyolitic units correlate with identifiable differences in δ2H and δ18O compositions, 3H concentrations, and water chemistry that imply equilibration at different temperatures and travel along different flow paths. (e) Based on measured 3H concentrations, we calculate that hot spring waters in the central part of the geyser basins mostly contain <2% post-1950 meteoric water, whereas waters discharged at the basin margins contain larger fractions of post-1950s meteoric water.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012230","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558227","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}

引用次数: 0

A HIMU-Like Endmember Hiding in the Turkana Depression Continental Lithospheric Mantle 隐藏在图尔卡纳坳陷大陆岩石圈地幔中的himu状端元

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-04 DOI: 10.1029/2024GC012086

Andrew R. Bollinger, Tyrone O. Rooney, Eric L. Brown, Frank C. Ramos

{"title":"A HIMU-Like Endmember Hiding in the Turkana Depression Continental Lithospheric Mantle","authors":"Andrew R. Bollinger, Tyrone O. Rooney, Eric L. Brown, Frank C. Ramos","doi":"10.1029/2024GC012086","DOIUrl":"https://doi.org/10.1029/2024GC012086","url":null,"abstract":"The fate of continental lithosphere during rifting is central to the process of continental extension. The continental lithospheric mantle comprises both depleted and enriched domains that may contribute to magma generation during extension. The East African Rift System is the archetypal example of a magma-rich continental rift, with the Turkana Depression containing the most extensive temporal record of mafic magmatism. There is debate as to the contribution of continental lithosphere to this mafic magmatism, with suggestions that HIMU-like isotopic signatures, often attributed to the continental lithosphere, are derived instead from a heterogeneous mantle plume. We focus on Miocene lavas that are characterized by radiogenic 206Pb/204Pb > 19.3, requiring a contribution from an HIMU-like endmember in their origin. We present a novel two-stage chromatographic metasomatism model that demonstrates that a HIMU-like endmember can be generated through time-integrated evolution within the continental lithospheric mantle. The first model stage uses an initial composition for the metasomatizing agent equivalent to a subduction magma to generate metasomes within the continental lithosphere during the Pan-African stabilization of the regional lithosphere (∼700 Ma). During Mesozoic rifting, the second model stage simulates destabilization and melting of these initial metasomes, re-enriching the surrounding lithosphere to generate new Mesozoic metasomes. Melts of these metasomes, when combined with melts of the regional asthenosphere, are consistent with the observed trace element and isotopic signatures of Turkana Miocene lavas. These findings suggest an important role for the continental lithospheric mantle during rifting and obviate the need for a complex, heterogenous plume.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012086","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558304","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}

引用次数: 0

Metasomatism and Melting of Cordilleran Lithosphere Resulting From Sediment Relamination During Shallow Subduction 浅俯冲过程中沉积物再分层引起的科迪勒拉岩石圈的交代和熔融作用

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-04 DOI: 10.1029/2025GC012300

C. D. Hiett, D. L. Newell, J. W. Shervais

{"title":"Metasomatism and Melting of Cordilleran Lithosphere Resulting From Sediment Relamination During Shallow Subduction","authors":"C. D. Hiett, D. L. Newell, J. W. Shervais","doi":"10.1029/2025GC012300","DOIUrl":"https://doi.org/10.1029/2025GC012300","url":null,"abstract":"Mantle xenoliths recovered from the modern backarc region of the northern Altiplano Plateau record metasomatism by slab-derived silicic melts, and a suite of Quaternary volcanics suggest that melting of accreted crustal material has persisted since shallow subduction in the Oligocene. Xenoliths recovered from a suite of high-K andesitic lava flows include phlogopite- and calcite-rich orthopyroxenites and harzburgites, a wehrlite, and a phlogopite schist. Xenolith hosted calcite yields δ13C and δ18O values of −2.49 to +0.77‰ VPDB and +15.8 to +16.4‰ VSMOW, respectively, reflecting inputs of subducted marine carbonates in the metasomatizing melt. Arc-like trace element patterns and 87Sr/86Sr ratios further support a subduction influence. Major and trace element characteristics of Quaternary potassic basalts and intermediate alkaline lavas, with the presence of mantle xenoliths, contradict magmatic differentiation or mixing models to yield intermediate composition melts. Instead, we suggest that intermediate composition lavas are derived from the melting of sediments accreted to the base of the continental lithosphere during shallow subduction in the late Eocene-Oligocene. Melting of accreted material produces silicic alkaline melts, which react with peridotite to produce alkaline basaltic melts and residual phlogopite-orthopyroxenites. These processes explain the observed xenolith suite and local high-K basaltic volcanism, and the intermediate lavas may represent sediment melts that ascended to the surface minimally altered by exploiting the Cusco-Vilconata fault system. These observations inform mass transfers during shallow subduction and melting and metasomatism in the lithospheric mantle, with implications for the generation of alkaline magmatism and rheologic weakening in cordilleran regions globally.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012300","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558228","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}

引用次数: 0

Mercury Deposition in South China Across the Ordovician-Silurian Transition: Implications for Climate Change 中国南方奥陶—志留纪过渡时期的汞沉积：对气候变化的影响

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-07-02 DOI: 10.1029/2024GC012122

Weiliang Kong, Zhen Qiu, Jiaqiang Zhang, Wen Liu, Qin Zhang

{"title":"Mercury Deposition in South China Across the Ordovician-Silurian Transition: Implications for Climate Change","authors":"Weiliang Kong, Zhen Qiu, Jiaqiang Zhang, Wen Liu, Qin Zhang","doi":"10.1029/2024GC012122","DOIUrl":"https://doi.org/10.1029/2024GC012122","url":null,"abstract":"Most of the global climate changes are closely associated with volcanic activity. However, the link between global cooling during the Ordovician-Silurian (O-S) transition and volcanism remains unclear due to limited constraints on large volcanic events before, during, and after the peak of the Hirnantian glaciation (PHG). Here, we present high-resolution mercury (Hg) concentrations and isotopes from South China across the O-S transition to assess volcanic activity and its contributions to climate changes. Anomalous Hg enrichments and volcanic-range Hg isotopes in samples above volcanic ash layers confirm the effectiveness of Hg as a tracer of volcanic events. Variations in Hg isotopes across the O-S transition reveal multiple Hg sources related to volcanic activity, that is, dominant volcanic Hg input during pre-PHG and post-PHG-2, deposition of volcanic-sourced atmospheric Hg(II) to seawater during PHG, and increased terrestrial Hg input from enhanced weathering during post-PHG-1. We propose that prolonged global cooling was driven by an albedo catastrophe caused by volcanic aerosols and sustained by reduced atmospheric CO2 levels due to enhanced organic carbon burial and weathering. This study highlights Hg as a tracer of volcanic activity and provides new evidence on the role of volcanism in driving climate changes across the O-S transition.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012122","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524691","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}

引用次数: 0

Toward Solving the Mystery of Elevated Tectonic Degassing in South Eastern Europe: Insights From Gas Discharges Along the Vardar Suture (North Macedonia) 解开东南欧高架构造脱气之谜：北马其顿瓦尔达尔缝合带天然气排放的启示

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-06-30 DOI: 10.1029/2025GC012177

L. Li Vigni, M. Temovski, C. Cardellini, K. Molnár, A. Ionescu, V. Mirčovski, K. Daskalopoulou, G. Chiodini, F. Parello, W. D’Alessandro

{"title":"Toward Solving the Mystery of Elevated Tectonic Degassing in South Eastern Europe: Insights From Gas Discharges Along the Vardar Suture (North Macedonia)","authors":"L. Li Vigni, M. Temovski, C. Cardellini, K. Molnár, A. Ionescu, V. Mirčovski, K. Daskalopoulou, G. Chiodini, F. Parello, W. D’Alessandro","doi":"10.1029/2025GC012177","DOIUrl":"https://doi.org/10.1029/2025GC012177","url":null,"abstract":"Tectonic carbon degassing is an important contributor to the global carbon cycle. South Eastern Europe is an active extensional tectonic region. This is the result of intense geodynamic events related to the closure of the Tethys Ocean, whose remnants include an ophiolite orogenic belt and the Vardar megasuture. In North Macedonia, regional active fault systems, seismic activity, Cenozoic-Quaternary volcanism, large-scale degassing, and low-enthalpy geothermal resources are widespread. Nonetheless, a geochemical characterization of the gas manifestations is missing from the literature. Toward this contribution, we report the first characterization of chemical and isotopic compositions of fluids from the main geothermal and cold gas manifestations of North Macedonia, and we explore their origins, the processes controlling their chemistry, and their relationships with the regional geodynamic situation. Gas samples were collected along the whole country, and were analyzed for both their chemical (He, H2, H2S, O2, N2, CO2, CH4, Ar) and isotopic composition (δ13C-CO2, He, Ar). Based on their chemistry, samples can be subdivided into three groups: (a) N2-dominated, (b) CO2-dominated, and (c) H2S-rich, which are geographically well separated, following regional distributions. The CO2-dominated group is the most widespread, highlighting the importance of geogenic carbon degassing in the study area. Its origin is prevailingly crustal (δ13C-CO2 = −4.6–+1.0‰ vs. V-PDB; R/RA = 0.1–1.8), but a significant, up to 25%, mantle contribution can be inferred from the He isotope composition.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012177","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514736","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}

引用次数: 0

Environmental and Calcification Impacts on the δ18O and δ2H Values of Cold-Water Coral Skeleton Fluid Inclusions 环境和钙化对冷水珊瑚骨架流体包裹体δ18O和δ2H值的影响

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-06-24 DOI: 10.1029/2024GC011981

Yao Wu, Dana Hölkermann, Amrei Grund, Sophie Warken, Norbert Frank

{"title":"Environmental and Calcification Impacts on the δ18O and δ2H Values of Cold-Water Coral Skeleton Fluid Inclusions","authors":"Yao Wu, Dana Hölkermann, Amrei Grund, Sophie Warken, Norbert Frank","doi":"10.1029/2024GC011981","DOIUrl":"https://doi.org/10.1029/2024GC011981","url":null,"abstract":"Coral skeletons exhibit a complex composition of mineral and organic components, with the water content playing a significant role in their structure. Water associated with organic matrices constitutes the major share, whereas nonstructural water (skeleton inclusion water) is present in much smaller amounts, typically less than 0.5 wt% of the coral skeleton. The isotopic composition of this water may reflect biomineralization processes or environmental conditions during skeleton formation. Here, we present fluid inclusion hydrogen and oxygen isotopic compositions of cold-water coral skeletons from Angola and Iceland. We confirmed the kinetic isotope fractionation when coral skeletons were crushed at a temperature of 120°C using a cavity ring-down spectroscopy analyzer. δ18O and δ2H values are not reproducible across analytical setups with varying temperature parameters. When coral fragments are encapsulated in a glass tube, the amount of released water and its isotopic signature are far more reproducible. δ18O and δ2H values of coral skeleton inclusion water from Angola show no significant differences between the Holocene and the last glacial period. The δ2H values are characterized by strong isotopic fractionation compared to seawater. Our study highlights that current methods do not adequately capture the variability in the initial δ18O and δ2H of the “quasi-free” skeleton inclusion water in coral aragonite. It is also possible that there are varying degrees of exchange of skeleton inclusion water with seawater. A better understanding of the coral calcification process is still necessary to establish a clearer link between the isotopic compositions of seawater and skeleton inclusion water.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011981","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144473152","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}

引用次数: 0

Tracking the Caribbean Magmatic Evolution: The British Virgin Islands as a Transition Between the Greater and Lesser Antilles Arcs 追踪加勒比海岩浆演化：英属维尔京群岛作为大安的列斯弧和小安的列斯弧之间的过渡

IF 2.9 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2025-06-19 DOI: 10.1029/2024GC012057

Noémie Bosc, Delphine Bosch, Mélanie Noury, Olivier Bruguier, Lény Montheil, Douwe J. J. van Hinsbergen, Jean-Jacques Cornée, Jonathan Outin, Mélody Philippon

{"title":"Tracking the Caribbean Magmatic Evolution: The British Virgin Islands as a Transition Between the Greater and Lesser Antilles Arcs","authors":"Noémie Bosc, Delphine Bosch, Mélanie Noury, Olivier Bruguier, Lény Montheil, Douwe J. J. van Hinsbergen, Jean-Jacques Cornée, Jonathan Outin, Mélody Philippon","doi":"10.1029/2024GC012057","DOIUrl":"https://doi.org/10.1029/2024GC012057","url":null,"abstract":"The British Virgin Islands (BVI) archipelago, located between the Greater Antilles and the Lesser Antilles, is a key location to study the geodynamic evolution of the Caribbean plate. Geochemistry of the studied samples reveals typical volcanic arc signatures, including a calc-alkaline affinity, strong negative HFSE anomalies, and LILE enrichment. The ɛHf values are homogeneous, indicative of a MORB-type mantle. Magmas were sourced from a homogeneous mantle wedge with less than 2% slab-derived sediment inputs, dominated by aqueous fluids. A concomitant melt component has been detected in the Peter and Norman Islands. U-Pb dating emphasizes an active magmatic period spanning over ca. 13 Myr (43–30 Ma), with a NE/SW decreasing age gradient. Thermobarometry data display a SW increasing emplacement depth from ∼6 to 13 km. Compared to the Greater and Lesser Antilles, this archipelago shows strong similarities with the extinct northern Lesser Antilles arc in terms of source and age. A geodynamical evolution model is proposed in which this archipelago represents a transition between the Greater and the Lesser Antilles arcs. The Oligocene cessation of magmatism (ca. 30 Ma) may coincide with a regionally documented lull in arc magmatic activity during which the Bahamas bank collided to the north. Paleomagnetic evidence of forearc sliver motion along the northeastern boundary of the Caribbean indicates a northward translation of the archipelago from a position above the Lesser Antilles subduction zone to its modern location along the highly oblique, strike-slip-dominated plate boundary, thus preventing the re-establishment of arc magmatism in the eastern Caribbean.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315039","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}

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