Geochemistry Geophysics Geosystems最新文献

{"title":"Efficacy of Assessing Magmatic Storage Depth Using Natural Samples, Experiments and Thermodynamic Models: A Case Study From Valles Caldera, NM (USA)","authors":"Magdalen A. Grismer,&nbsp;Laura E. Waters,&nbsp;Gordon M. Moore,&nbsp;Gabriela A. Farfan","doi":"10.1029/2025GC012241","DOIUrl":"https://doi.org/10.1029/2025GC012241","url":null,"abstract":"<p>Estimates of magmatic storage are typically made using mineral assemblages in natural samples, experiments and thermodynamic models (e.g., MELTS), where each method has limitations. Here, we compare each of these methods to assess their utility in estimating storage conditions for post-collapse, two-feldspar high-silica rhyolites (HSRs) sourced from Valles Caldera, NM (USA). We focus on the Valle Grande HSRs, which have known whole rock, glass compositions, crystallinities and storage conditions (∼750–770°C; ∼130–165 MPa). Equilibrium experiments that overlap with magmatic storage conditions determined from sample petrology have glass and mineral compositions that match those in the natural samples, suggesting that the phenocryst assemblage is accurately recording pre-eruptive conditions. RMELTS reproduces differing aspects of the natural samples and experiments, but generally confirm storage conditions (751–758°C; 179–215 MPa) recorded by the petrology of the post-collapse high-silica rhyolites. RMELTS reproduces the experimentally determined phase-in curves within ±5°C, at pressures &gt;125 MPa. Below 125 MPa, RMELTS overpredicts the stability of the experimental quartz, sanidine and anorthoclase. We apply the RMELTS geothermobarometer to the Glass Mountain obsidians (two-feldspar HSRs) to evaluate possible reasons for the agreement between RMELTS, experiments, and Valle Grande HSRs. The RMELTS geothermobarometer overpredicts the Glass Mountain obsidians' temperatures by 50–77°C, and likely underpredicts pressures. RMELTS predicts a common co-saturation temperature of ∼750°C for these two HSRS. We find that RMELTS recovers the storage temperature and pressures for Valle Grande HSRS because they have temperatures of ∼750°C, contain &lt;30% total crystallinity, are near equilibrium and are stored at &gt;125 MPa.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012241","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589611","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 Tectonic Responses in the Overriding Plate During the Tethyan Convergence and the Progressive Extrusion Process in Sundaland: Insights From the Wuliangshan Massif, SE Tibetan Plateau","authors":"Qinying Wu,&nbsp;Wei Lin,&nbsp;Lingtong Meng,&nbsp;Yin Wang,&nbsp;Fei Liu,&nbsp;Yang Chu,&nbsp;Wei Wei,&nbsp;Michel Faure,&nbsp;Vuong Van Nguyen,&nbsp;Hoai Luong Thi Thu,&nbsp;Chao Song,&nbsp;Zhao Guo","doi":"10.1029/2025GC012371","DOIUrl":"https://doi.org/10.1029/2025GC012371","url":null,"abstract":"<p>The overriding plate commonly accumulates less strain than the subducted plate during continental collision. Analyzing plate interactions from the perspective of the overriding plate provides important insights into orogenic dynamics. In the southeastern Tibetan Plateau, the Wuliangshan massif, as a key region of the overriding plate, records tectonic events related to the closure of both the Paleo-Tethys and Neo-Tethys. In this study, we present detailed structural analysis, Titanium-in-quartz geothermometry, and zircon U-Pb and Hf isotopic data. These results indicate that the Wuliangshan massif experienced rapid subsidence and deposition within a short period from 260 to 250 Ma in a back-arc tectonic setting. The polyphase deformation events were recognized in the Wuliangshan massif. The ductile syn-metamorphism D₁ event, characterized by a top-to-the-SE ductile shearing under middle-to high-temperature conditions, represents the tectonic response to the collision between the Sibumasu block and the Indochina block occurred at ca. 250–246 Ma. The D₂ deformation is expressed by E-directed thrusts and E-verging folds coeval with a slaty cleavage. The D₃ deformation is marked by SW-directed thrusts and SW-verging folds. The D₂ and D₃ events correspond to positive flower structures related to transpression along the Chongshan-Lancang River fault and the Ailaoshan-Red River fault, respectively. The D₂-related Chongshan-Lancang River fault accommodated the southward extrusion of the western part of Sundaland occurred at 32–27 Ma. The southeastward extrusion of the entire Sundaland was accommodated by the D₃-related Ailaoshan-Red River fault at 27–23 Ma.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012371","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582367","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":"Performance of the 3F4M Noblesse–HR Noble Gas Mass Spectrometer for Multicollection Ne-Ar-N2 Analyses","authors":"L. Zimmermann,&nbsp;E. Füri,&nbsp;J. Boulliung,&nbsp;J. M. Saxton","doi":"10.1029/2025GC012247","DOIUrl":"https://doi.org/10.1029/2025GC012247","url":null,"abstract":"<p>The Noblesse–HR noble gas mass spectrometer was designed for multicollection analyses of different sets of noble gas isotopes with a fixed detector array under static conditions. At the Centre de Recherches Pétrographiques et Géochimiques (CRPG, Nancy, France), we developed a novel procedure to measure nitrogen (N₂) abundance and isotope ratio (²⁸N₂/²⁹N₂) using the 3 Faraday–4 Multiplier (3F4M) system. This procedure simultaneously acquires ion signals for ¹⁴N¹⁴N⁺ (Fa2), ¹⁵N¹⁴N⁺ (Fa1), and ¹⁵N¹⁵N⁺ (IC0). An in-house-built purification system ensures ultra-low blank levels (≤1 × 10⁻¹² mol N₂), while air standard measurements monitor detector sensitivity and instrumental mass fractionation. Here, we assess the effects of the source and zoom optics settings on mass resolution (MR), mass resolving power (MRP), and peak alignment, and identify potential contributions from interfering species. The performance of the Noblesse–HR for multicollection Ne-Ar-N₂ analyses was evaluated over several months and across varying gas quantities introduced into the mass spectrometer. Average sensitivities, with 1σ relative scatter, were 5.05 × 10⁻⁵ A/Torr ±1.02% for ²⁰Ne, 2.86 × 10⁻⁴ A/Torr ±1.37% for ³⁶Ar, and 1.18 × 10⁻⁴ A/Torr ±1.90% for N₂. Corresponding isotopic ratios were ²⁰Ne/²²Ne = 9.80 ± 0.34%, ²¹Ne/²²Ne = 2.90 × 10⁻² ± 1.53%, ⁴⁰Ar/³⁶Ar = 296.19 ± 0.10% (over 20 days), ³⁸Ar/³⁶Ar = 0.1876 ± 0.28%, and ²⁸N₂/²⁹N₂ = 135.92 ± 0.05%. These results demonstrate that the 3F4M Noblesse–HR provides precise, accurate, and reproducible data, adapted for studying planetary materials.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582366","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 Origins of Africa's Upper Mantle Discontinuities","authors":"Jean-Joel Legre,&nbsp;Tolulope Olugboji","doi":"10.1029/2025GC012315","DOIUrl":"https://doi.org/10.1029/2025GC012315","url":null,"abstract":"<p>Enigmatic discontinuities in the upper mantle beneath Africa, such as the mid-lithosphere and X-discontinuities, have prompted various theories regarding their causes. However, most studies rely on S-to-P receiver functions, raising concerns about resolution. In this study, we enhance the depth-resolution of mantle discontinuities using high-resolution P-to-S receiver functions that are free from crustal reverberations. Our analysis reveals the depths and the polarities of both single and multiple discontinuities. The most prevalent observation is an unpaired (i.e., no high velocity discontinuity beneath or above) low-velocity discontinuity at depths between 50 and 100 km, which shows minimal secular variation. Additionally, paired discontinuities are detected either within or below the heterosphere. Comparisons with thermal, chemical and geophysical models that predict rapid seismic velocity gradients due to partial-melting (induced by volatiles or sub-solidus grain-boundary mechanisms) suggest that the common sharp velocity drop is most likely caused by a sub-solidus mechanism, while the paired discontinuities, including a newly resolved high-velocity discontinuity, may indicate the base of a melt layer. This mantle stratification might be linked to magmatism or remnants of past continental assembly.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012315","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573460","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":"Is One Sample Enough? Testing the Importance of Lateral Sedimentary Variability in Cyclostratigraphy","authors":"Fangfang Chen,&nbsp;Ross N. Mitchell","doi":"10.1029/2024GC012087","DOIUrl":"https://doi.org/10.1029/2024GC012087","url":null,"abstract":"<p>Cyclostratigraphic studies of sedimentary rocks traditionally sample assuming that one sample per sedimentary horizon is sufficient. But is one sample enough? This is important to address because if two or more measurements per horizon improve data quality, then sampling schemes should strike a balance between sampling resolution (stratigraphically) and bedding variation (laterally). This study aims to address this fundamental question by statistically comparing the results from data sets based on individual versus multiple measurements per stratigraphic horizon. Using magnetic susceptibility as our proxy, which can be readily measured in situ for such a study, we evaluate both field-based (KT-10R) and laboratory-based (MFK2-FA Kappabridge) susceptibility data and compare their results. For the Guanmenshan Formation, a Paleoproterozoic (ca. 2.16 Ga) platform carbonate of North China craton, we find broad agreement between the two means of measurement. But the KT-10R field meter, with multiple measurements per bed, shows increased statistical significance in identifying Milankovitch cycles. This dual comparison between lab- and field-based methods and single versus multiple measurements per bed demonstrates that measuring one sample per bed reduces accuracy in determining the true average proxy value of a bed. Thus, averaging the natural variation in composition along a stratigraphic layer (spatial resolution)—typically ignored when only one sample is taken—may be as important as the precision of measurement or the sampling interval. Our results suggest that <i>n</i> = 2 samples/measurements per bed are better than just <i>n</i> = 1, and results are best for <i>n</i> = 3 per layer.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573461","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":"Mantle Flow and Anisotropy in Subduction Zones: Modeling and Clustering of Olivine Textures","authors":"Yijun Wang,&nbsp;Ágnes Király,&nbsp;Clinton P. Conrad,&nbsp;Valerie Maupin","doi":"10.1029/2025GC012160","DOIUrl":"https://doi.org/10.1029/2025GC012160","url":null,"abstract":"<p>The mantle near Earth's subduction zones endures intense deformation that generates anisotropic rock textures. These textures can be observed seismically and modeled geodynamically, but the complexity of this deformation makes analyses of these textures difficult. In this study, we apply time-series clustering analysis to tracers within subduction models, allowing for the identification of regions in the subduction zone with common deformation histories and olivine crystallographic-preferred orientation development. We compare olivine texture evolution predicted using different methods in both retreating and stationary-trench settings. Our results reveal distinct variations in olivine texture, indicating that both seismic and viscous anisotropy can exhibit substantial heterogeneity within the mantle wedge, sub-slab, and subducting plate regions. For retreating trenches, olivine textures are strongest in the mid-depth mantle wedge region about 200 km away from the trench between 100 and 300 km depth. Our study shows that trench-normal olivine <i>a</i>-axis orientations dominate in the center of subduction zones. Toroidal flow around slab edges generates a mix of trench-normal, trench-parallel, and oblique fast seismic directions. Textures and anisotropy are stronger for the retreating trench model than for the stationary trench model since more deformation has been accumulated due to trench motion. These findings provide insights for interpreting seismic anisotropy in subduction zones and highlight the importance of considering texture heterogeneity, as characterized by clustering algorithms, when analyzing both geodynamic models and seismic observations of subduction zones.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 7","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012160","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573462","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 Cretaceous Extensional Collapse Driven by Delamination in Central Tibet Prior to India-Asia Collision","authors":"Yao Xiao,&nbsp;Xi Jun Liu,&nbsp;Hao Wu,&nbsp;Min Liu,&nbsp;Hai Yong Liu,&nbsp;Yu Jia Song,&nbsp;Fei Liu","doi":"10.1029/2025GC012305","DOIUrl":"https://doi.org/10.1029/2025GC012305","url":null,"abstract":"<p>A diverse range of dikes in the western Lhasa–Qiangtang collision zone provides constraints on the evolution of post-collisional tectonomagmatic processes and the growth of the Tibetan Plateau. We report geochronological, geochemical, and Sr–Nd–Hf isotopic data for granitic dikes in the Rebang area of the Northern Lhasa Block, northern Tibet. Zircon U-Pb dating of the granitic dikes reveals abundant inherited zircons with ages ranging from 1869 to 98.8 Ma, and the youngest age groups (83.9–82.0 Ma) indicate that they formed during the Late Cretaceous. The granitic dikes are characterized by high Sr and low Y contents and high Sr/Y ratios, and they have adakitic geochemical affinities and variable zircon <i>ε</i>_Hf(<i>t</i>) (−6.01 to +9.82) and whole-rock <i>ε</i>_Nd(<i>t</i>) (−0.55 to +1.43) values. These features, together with the high Mg# values, suggest that the Rebang granitic dikes are derived by partial melting of thickened juvenile lower crust with variable degrees of contamination by mantle peridotite. The co-occurrence of widely distributed dikes and thick-bedded terrestrial molasses in the Late Cretaceous suggested that the central Tibet underwent post-collisional extensional collapse, which was triggered by lithospheric delamination. We favor that isostatic rebound in response to delamination induces rapid surface uplifting and gravitational collapse in the Lhasa–Qiangtang collision zone. Additionally, our research proposes that the post-collision extensional collapse in the Late Cretaceous plays an important role in the vertical growth of the Tibetan Plateau.</p>","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/10.1029/2025GC012305","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558184","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 Oceanic Plateau Induced Subduction Zone Jump From Proto- to Paleo-Tethys in East Kunlun, Northern Tibetan Plateau","authors":"Rutao Zang,&nbsp;Yunpeng Dong,&nbsp;Dazhi Jiang,&nbsp;Dengfeng He,&nbsp;Shengsi Sun,&nbsp;Bo Hui,&nbsp;Bin Zhang","doi":"10.1029/2025GC012211","DOIUrl":"https://doi.org/10.1029/2025GC012211","url":null,"abstract":"<p>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.</p>","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}

{"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,&nbsp;Melodie E. French,&nbsp;Noah J. Phillips","doi":"10.1029/2025GC012221","DOIUrl":"https://doi.org/10.1029/2025GC012221","url":null,"abstract":"<p>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 (&gt;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 (&lt;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.</p>","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}

{"title":"Eoarchean–Paleoproterozoic Tectonothermal History of the Acasta Gneiss Complex Constrained by Titanite and Apatite Petrochronology","authors":"Omar Khalil Droubi,&nbsp;Ann M. Bauer,&nbsp;Chloë Bonamici,&nbsp;William O. Nachlas,&nbsp;Joshua M. Garber,&nbsp;Michael J. Tappa,&nbsp;Jesse R. Reimink","doi":"10.1029/2025GC012294","DOIUrl":"https://doi.org/10.1029/2025GC012294","url":null,"abstract":"<p>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.</p>","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}