Geochemistry Geophysics Geosystems最新文献

{"title":"Sediment Depositional History and Processes for the Eurasian Basin Since 54 Ma, Arctic Ocean","authors":"Pingchuan Tan,&nbsp;Chunyang Wang,&nbsp;Fei Wang,&nbsp;Jiabiao Li","doi":"10.1029/2025GC012201","DOIUrl":"https://doi.org/10.1029/2025GC012201","url":null,"abstract":"<p>The Eurasian Basin in the Arctic Ocean, comprising the Amundsen and Nansen Basins separated by the Gakkel Ridge, has sediment deposits up to 4–5 km thick. However, its sedimentation history and processes remain poorly understood. Using 31 seismic profiles, we have estimated deposition rates for 54 Ma. From 54 to 45 Ma, the Nansen Basin averaged ∼15 cm/kyr, while the Amundsen Basin exhibited higher but variable rates (15–50 cm/kyr). From 45 to 20 Ma, the Amundsen Basin's rates decreased significantly, dropping to 6–7 cm/kyr (34–45 Ma) and ∼3.5 cm/kyr (20–34 Ma). Meanwhile, the Nansen Basin maintained higher rates (∼12 cm/kyr to ∼5 cm/kyr). After 20 Ma, sedimentation rates diverged further. The Nansen Basin stabilized at ∼5 cm/kyr and was significantly influenced by glaciation and iceberg rafting, while the Amundsen Basin continued to decline to ∼2 cm/kyr, with pelagic sediments dominated by sea-ice and iceberg rafting, and debris flows near the Lomonosov Ridge. The Nansen Basin's higher rates are likely due to its proximity to the Barents and Laptev Sea shelves, while the general declined rates across the basin are related to basin expansion, climate cooling, and reduced tectonic activity. Additionally, the Eurasian Basin's sedimentation is shaped by two phases of Siberian river activity. Before 45 Ma, the Lena and Indigirka rivers dominated, particularly near the eastern Laptev Sea Shelf. After 45 Ma, the Pyasina and Yenisey rivers became the main contributors, with significant sediment delivery through the St. Anna Trough. Sediment deposits (0.6–1 km) along the Gakkel Ridge (70°E−100°E) are also caused by these processes.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171680","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":"Constraining Solid Dynamics, Interface Rheology, and Slab Hydration in the Hikurangi Subduction Zone Using 3-Dimensional Fully Dynamic Models","authors":"D. Douglas,&nbsp;J. Naliboff,&nbsp;M. R. T. Fraters,&nbsp;J. Dannberg,&nbsp;D. Eberhart-Phillips,&nbsp;S. Ellis","doi":"10.1029/2024GC011824","DOIUrl":"https://doi.org/10.1029/2024GC011824","url":null,"abstract":"<p>Simulating present-day solid Earth deformation and volatile cycling requires integrating diverse geophysical data sets and advanced numerical techniques to model complex multiphysics processes at high resolutions. Subduction zone modeling is particularly challenging due to the large geographic extent, localized deformation zones, and the strong feedbacks between reactive fluid transport and solid deformation. Here, we develop new workflows for simulating 3-dimensional thermal-mechanical subduction and patterns of volatile dehydration at convergent margins, adaptable to include reactive fluid transport. We apply these workflows to the Hikurangi margin, where recent geophysical investigations have offered unprecedented insight into the structure and processes coupling fluid transport and solid deformation across broad spatiotemporal scales. Geophysical data sets constraining the downgoing and overriding plate structure are collated with the Geodynamic World Builder, which provides the initial conditions for forward simulations using the open-source geodynamic modeling software code ASPECT. We systematically examine how plate interface rheology and hydration of the downgoing plate and upper mantle influence Pacific–Australian convergence and seismic anisotropy. Models prescribing a plate boundary viscosity of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>5</mn>\u0000 <mo>×</mo>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>20</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $5times 1{0}^{20}$</annotation>\u0000 </semantics></math> Pa s best reproduce observed plate velocities, and changing the configuration of the Pacific–Australia plate boundary directly influences the modeled plate motions. Models considering hydrated olivine fabrics best reproduce observations of seismic anisotropy. Predicted patterns of slab dehydration and mantle melting correlate well with observations of seismic attenuation and arc volcanism. These results suggest that hydration-related rheological heterogeneity and related fluid weakening may strongly influence slab dynamics. Future investigations integrating coupled fluid transport and global mantle flow will provide insight into the feedbacks between subduction dynamics, fluid pathways, and arc volcanism.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011824","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171954","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 First-Order Crustal Structure and Basin Architecture of the Canadian Arctic Margin","authors":"Randell Stephenson,&nbsp;Goodluck Anudu","doi":"10.1029/2025GC012196","DOIUrl":"https://doi.org/10.1029/2025GC012196","url":null,"abstract":"<p>First-order sedimentary isopach and depth-to-Moho maps have been produced for the first time along the Canadian Arctic margin from legacy seismic profiles, calibrated with two-dimensional gravity and magnetic modeling and augmented by some younger passive seismic and exploration seismic data. These maps show margin-scale structural patterns that can be interpreted in terms of fundamental tectonic processes of lithosphere deformation. The Canadian Arctic margin from the Beaufort Sea to Sever Spur, but not beyond it, is a typical passive continental margin along the Canada Basin ocean. However, beyond Sever Spur through to the Lincoln Shelf, the margin comprises a narrow linear sedimentary basin overlying an axis of crustal thinning embedded within continental lithosphere. This basin formed by intracontinental (trans)extension at least in part after the main HALIP magmatic events that helped build Alpha Ridge on its northern margin. This segment of the margin has a tectonic affinity more facing the Late Cretaceous and Cenozoic North Atlantic-Baffin Bay-Arctic extensional regime rather than the earlier Canada Basin extensional regime. These interpretations, which together provide a “Canadian” boundary condition on models of Amerasia Basin origin and evolution, are clearly speculative given the resolution of the available geophysical data. They are presented here, nevertheless, accompanied by a thorough overview of pertinent recent literature, with the aim of helping to prompt and inform further debate about the tectonic history of the Arctic Ocean.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012196","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148387","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":"Eruption, Emplacement and Internal Architecture of Massive and Super-Massive Inflated Submarine Basalt Lava Flows, Walvis Ridge Hotspot Track, IODP Expeditions 391/397T","authors":"John W. Shervais,&nbsp;Jesse L. Scholpp,&nbsp;Mike Widdowson,&nbsp;Wendy R. Nelson,&nbsp;Katherine E. Potter,&nbsp;Stephan Homrighausen,&nbsp;Drew White,&nbsp;David Buchs,&nbsp;Daniel E. Heaton,&nbsp;Aaron Avery,&nbsp;Rajneesh Bhutani,&nbsp;Robert A. Duncan,&nbsp;Cornelia Class,&nbsp;Mbili Tshiningayamwe,&nbsp;Yusuke Kubota,&nbsp;Xiao-Jun Wang,&nbsp;Tao Wu,&nbsp;William W. Sager,&nbsp;Kaj Hoernle,&nbsp;Tobias Höfig","doi":"10.1029/2024GC012145","DOIUrl":"https://doi.org/10.1029/2024GC012145","url":null,"abstract":"<p>Massive submarine basalt flows were sampled at five sites on the Tristan-Gough-Walvis hotspot track in the South Atlantic by International Oceanic Discovery Program Expeditions 391/397T, where the plume was interacting with a mid-ocean ridge, a setting similar to that the of modern Iceland. High resolution XRF core scans document significant internal chemical variations with depth in these flows. Some of this reflects basal olivine accumulation. However, some examples have “scallop-shaped” patterns that are interpreted to represent influxes of new magma during flow lobe inflation with successive lava injections focused toward the base of the flow unit. Olivine concentration in the deeper parts of the flow is interpreted to reflect top-down tapping of a vertically zoned magma chamber, with the upper part of the chamber erupting first, and successive eruptive pulses tapping progressively deeper levels of the stratified chamber. The occurrence of massive submarine lava flows requires high eruptive fluxes relative to pillow lava formation. Propagation of these massive flows is favored by (a) high sea water confining pressures, which inhibit vesiculation and keep effective viscosity low and dissolved volatile content high, and (b) chill zones and thick viscoelastic crusts of quenched lava on the flow tops, which effectively insulate the flow interior from ambient temperatures. The formation of a thin film of super-heated steam on the upper flow surface may similarly enhance the insulation. Evidence suggests that similar massive flows on the seafloor may extend many kilometers from their vents.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 6","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012145","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148389","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":"A Late Paleozoic Hydrothermal Gold Mineralization Event in the Northern Margin of the North China Craton: Evidence of In Situ Apatite U-Pb Dating and Hg Isotope Tracing of the Giant Hadamengou Gold Deposit","authors":"Tingting Xiao,&nbsp;Deyou Sun,&nbsp;Cheng Xu,&nbsp;Zhendong Tian,&nbsp;Anbo Luo,&nbsp;Changzhou Deng,&nbsp;Runsheng Yin","doi":"10.1029/2024GC012053","DOIUrl":"https://doi.org/10.1029/2024GC012053","url":null,"abstract":"<p>The northern margin of the North China Craton (NCC) hosts large numbers of hydrothermal gold deposits, with mineralization ages ranging from the Paleozoic to Mesozoic eras. The genesis of these deposits has been primarily ascribed to magmatic-hydrothermal or crustal-metamorphic fluid models. The Hadamengou gold deposit (&gt;170 t Au), the largest gold deposit in this region in terms of gold reserve, is still unclear on either the mineralization age or the source of metals. In this work, in situ apatite (hydrothermal) U-Pb dating and Hg isotope tracing were employed to address the two key issues. In situ apatite U-Pb dating revealed a mineralization age of 335 ± 10 Ma (2SD), coinciding with the period of Paleo-Asian Ocean subduction. Mercury isotope analyses yielded near-zero Δ¹⁹⁹Hg values (−0.01 ± 0.06‰, SD) in ores and sulfides, consistent with results for the nearby ∼360 to ∼330 Ma Dahuabei granitic pluton (−0.09 ± 0.03‰, SD), suggesting a close genetic connection between them. The results of this study support that the Hadamengou belongs to a Late Paleozoic hydrothermal gold mineralization system, which was formed closely related to subduction of the Paleo-Asian Ocean. This study demonstrates a Late Paleozoic gold mineralization event and a good potential for exploration of gold around Late Paleozoic granitic plutons in the northern margin of the NCC.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012053","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144126061","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":"Insights From Megacryst-Included Zircon Dates on the Spatial Extent of Magma Mixing in the Tuolumne Intrusive Suite, California, USA","authors":"Elena Watts,&nbsp;Julia Ye,&nbsp;Sean P. Gaynor,&nbsp;Valbone Memeti,&nbsp;Blair Schoene","doi":"10.1029/2024GC012120","DOIUrl":"https://doi.org/10.1029/2024GC012120","url":null,"abstract":"<p>The spatial extent of mixing between separately emplaced batches of magma is a key component in understanding the incremental assembly of plutons. Potassium feldspar megacrysts (&gt;3 cm length) in granodioritic rocks are hypothesized to record magma mixing and transport over hundred kyr timescales. CA-ID-TIMS U-Pb dates from zircon inclusions within 11 new megacryst samples and their surrounding matrix from the Tuolumne Intrusive Suite are presented as a means of evaluating the extent of mixing across a less than two km wide gradational contact. Megacrysts from within the gradational contact yielded zircon dates consistent with mixing or transport from the older porphyritic Half Dome Granodiorite, but the zircon included in megacrysts from the younger Cathedral Peak Granodiorite show no evidence of interaction with the porphyritic Half Dome. These results, along with the trace element geochemistry of the zircon, suggest that the porphyritic Half Dome and Cathedral Peak magmas where we sampled were not comagmatic, which constrains the width of a mixing front to the kilometer scale gradational contact between these units. From within this gradational contact, we do find evidence of mixing consistent with prior studies. Differences between the core- and rim-included zircon date spectra also suggest that protracted growth is recorded in some K-feldspar megacrysts but may not be a requirement for forming them.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012120","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144126059","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":"Recent Advances in the Use of Drill Cuttings for Determining Subduction Zone Structure, Stratigraphy, and Stress State","authors":"P. H. Cornard,&nbsp;A. M. Schleicher,&nbsp;C. Regalla,&nbsp;M. Hamahashi,&nbsp;M. Kitamura,&nbsp;R. Fukuchi,&nbsp;K. T. Pickering,&nbsp;H. Kitajima,&nbsp;T. Wiersberg","doi":"10.1029/2024GC012094","DOIUrl":"https://doi.org/10.1029/2024GC012094","url":null,"abstract":"<p>Obtaining in situ samples from active subduction systems is critical for assessing the material properties and geological evolution of rocks and sediments that host plate boundary deformation, and advancing our understanding of the processes that lead to fault locking and rupture. However, accessing and coring these materials is challenging, and commonly requires riser drilling. The International Ocean Discovery Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project has successfully used ultradeep riser-drilling to collect deep crust samples via core or cuttings. This paper reviews analytical methods and challenges associated with interpreting subduction zone processes from cuttings. A key advantage of analyzing cuttings is the ability to collect real time data on the lithological, biostratigraphical, structural and geochemical properties of the drilled materials. Combining these data with logging-while-drilling and mud gas logging data permits the generation of depth profiles of lithological variation and deformation structures. Significant limitations of cuttings include small sample size, contamination from cement and drilling fluids, the formation of drilling-induced cohesive aggregates (DICAs), and vertical mixing during ascent. While it is impossible to overcome all these limitations, this study provides and includes examples illustrating how these issues can impact the assessment of the geological formation. Despite these challenges, cuttings have advanced our knowledge of subduction zone stratigraphy, fault friction, fluid flow, and stress distribution. This has significantly improved our understanding of earthquake mechanics, megathrust fault processes and locking/rupture mechanisms along plate fault boundaries. Future riser-drilling operations are therefore crucial for understanding megathrust earthquakes and fault behavior.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012094","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144118237","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":"Using Subducting Plate Motion to Constrain Cascadia Slab Geometry and Interface Strength","authors":"M. Fraters,&nbsp;M. Billen,&nbsp;J. Naliboff,&nbsp;L. Staisch,&nbsp;J. Watt,&nbsp;Haoyuan Li","doi":"10.1029/2024GC011895","DOIUrl":"https://doi.org/10.1029/2024GC011895","url":null,"abstract":"<p>Subduction zones are home to multiple geohazards driven by the evolution of the regional tectonics, including earthquakes, volcanic eruptions and landslides. Past evolution builds the present-day structure of the margin, while the present-day configuration of the system determines the state-of-stress in which individual hazardous events manifest. Regional simulations of subduction zones provide a tool to synthesize the tectonic history of a region and investigate how geologic features lead to variations in the state of stress across the subduction system. However, it is challenging to design regional models that provide a force-balance that is consistent with the large-scale motion of surrounding tectonic plates while also not over-constraining the solution. Here, we present new models for the Cascadia subduction zone that meet these criteria and demonstrate how the motion of the subducting Juan de Fuca plate can be used to determine the along-strike variations in the viscous (long-term) coupling across the plate boundary. All successful models require lower viscous coupling in the northern section of the trench compared to the central and southern sections. However, due to uncertainties in the geometry of the Cascadia slab, we find that there is a trade-off between along-strike variation in viscous coupling and slab shape. Better constraints on the slab shape, and/or use of other observations are needed to resolve this trade-off. The approach presented here provides a framework for further exploring how geologic features in the overriding plate and the properties of the plate boundary region affect the state-of-stress across this and other subduction zones.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011895","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144118236","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":"From Magma Formation to Eruption: Temperature Path of Two Late Carboniferous Post-Collisional Calderas (Bohemian Massif)","authors":"I. Olšanská,&nbsp;F. Tomek,&nbsp;C. Robustelli Test,&nbsp;E. Zanella,&nbsp;M. Svojtka,&nbsp;J. Trubač,&nbsp;F. Cifelli,&nbsp;F. Finger","doi":"10.1029/2025GC012217","DOIUrl":"https://doi.org/10.1029/2025GC012217","url":null,"abstract":"<p>The thermal evolution of magmatic systems of the Altenberg-Teplice and Tharandter Wald calderas, which erupted during the terminal post-collisional phase of the Variscan orogeny in the Bohemian Massif, was investigated. The zircon saturation temperatures and Ti-in-zircon thermometer indicate that the intrusive and extrusive units of the two calderas were sourced from medium- to high-temperature (∼770–930°C) felsic lower crustal magma. Using an integrated rock-magnetic and paleomagnetic approach through thermal demagnetization and stepwise thermomagnetic curves, it was estimated that intracaldera ignimbrites reached temperatures of 550–600°C. The low-temperature component (350–450°C) likely corresponds to the alteration of magnetic minerals during cooling or late-stage magmatic/hydrothermal events. Placing these findings in the broader context of Variscan post-collisional magmatism might suggest a trend of decreasing magma temperatures from 330 Ma to 302 Ma within the two lower-to mid-crustal (Moldanubian) and upper-crustal (Saxothuringian) units of the Bohemian Massif, possibly reflecting the cooling of the hot collisional orogen. Lastly, we suggest that a combination of zircon temperature estimates with the rock-magnetic methods may provide a comprehensive framework for further research on the thermal evolution of felsic magmatic systems.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012217","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144118238","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":"Late Mesozoic Tectonic-Magmatic Evolution of the Tongbai Orogen, Central China: Implications for Granites Petrogenesis and Gold Mineralization","authors":"Lei Ai,&nbsp;Xianquan Ping,&nbsp;Jianping Zheng,&nbsp;Yuping Su,&nbsp;Qiang Ma,&nbsp;Xianbin Shi,&nbsp;Tianci Huang","doi":"10.1029/2025GC012166","DOIUrl":"https://doi.org/10.1029/2025GC012166","url":null,"abstract":"<p>Late Mesozoic granitoids are widely distributed throughout the East Qinling-Tongbai-Dabie orogenic belt and its periphery, while large-scale gold deposits during the same period were primarily found in the Xiaoqinling-Xiong'ershan area, west of the Tongbai orogen. The deep dynamic mechanisms behind this phenomenon are still poorly understood. In this study, we conducted a comprehensive analysis of geochronology, petrology, geochemistry and Sr-Nd-Hf isotopes on the late Mesozoic Yuhuangding (YHD) and Zhulindian (ZLD) plutons in the Tongbai orogen. Zircon U-Pb dating yields intrusion ages of ca. 140, 131, and 132 Ma for the YHD and ZLD monzogranites and mafic microgranular enclaves within the ZLD pluton, respectively. Both the monzogranites exhibit adakitic affinities with a thickened lower crust origin. Meanwhile, the Sr-Nd-Hf isotopic composition of the YHD monzogranites indicates an affinity with the northern Qingling (N-QL) crust, whereas the younger ZLD monzogranite shows a distinct linkage to the southern North China Craton (S-NCC) basement. Such isotopic dichotomy suggests that the Tongbai orogenic belt exhibits a “crocodile-mouth” crust architecture, characterized by the northward subduction of the N-QL crust and the southward wedged S-NCC crust. Research data on granitoids throughout the East Qinling-Tongbai-Dabie orogenic belt, including their geochemical and isotopic variations, along with the seismic velocity profiles, indicate that the East Qinling-Tongbai-Dabie orogenic belt underwent lower crustal delamination and thinning during the early Cretaceous, which resulted in the formation of the observable high-velocity zone (HVZ) within the upper mantle. The discontinuities of the HVZ suggest that the intense extensional environment following delamination probably created lithospheric weak zones along the west of Nanyang Basin, which in turn facilitated the contribution of mantle-derived materials and heat, promoting the formation of granitoids and gold mineralization. These processes may be triggered by subduction and/or roll-back of the Paleo-Pacific plate.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012166","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144117834","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}