Geochemistry Geophysics Geosystems最新文献

{"title":"Water in Eclogite and Pyroxenite Xenoliths From the Bottom 100 km of the Slave Craton (Canada) Mantle Root","authors":"Esther Schmädicke,&nbsp;Jürgen Gose,&nbsp;Thomas Stachel","doi":"10.1029/2024GC011922","DOIUrl":"https://doi.org/10.1029/2024GC011922","url":null,"abstract":"<p>Major and trace elements, including H₂O, were determined in garnet and clinopyroxene to constrain the evolution of mantle xenoliths from Diavik, Canada. The 20 samples, derived from 120 to 220 (240) km depth, define a geotherm equivalent to 37 mW/m² surface heat flow and include three eclogite (A, B, C) and two pyroxenite (B, C) types (A: High Ca/low Mg, B: High Ca/high Mg; C: Low Ca/high Mg). C-type samples invariably come from lower depth (&lt;175 km) than B-types (&gt;200 km); type-A eclogite is present in both intervals. The contents of hydroxyl (referred to as “structural H₂O” and given as μg/g H₂O) in clinopyroxene of B-type eclogite and pyroxenite (360–1,149 and 225–1,509 μg/g) are higher than in C-type samples (123–165 and 321–393 μg/g). Moreover, clinopyroxene in eclogite has lower H₂O contents relative to pyroxenite. Structural H₂O of clinopyroxene is positively correlated to Cu, Ni, and K but not to major elements. In garnet, contents of structural H₂O are low (0–41 μg/g) and correlate neither with rock type nor with mineral composition. Most garnets additionally contain molecular (non-structural) water, being correlated to compositional parameters of both garnet (positive: Mg; negative: Ca, Sr, Be, Na) and clinopyroxene (positive: MREE, Ca, Th; negative: Al, K, Na, Li). Structural H₂O in clinopyroxene and garnet does not correspond to PT conditions but was affected by secondary, metasomatic processes. Most likely, pyroxenite formed from eclogite by metasomatic changes resulting in lower clinopyroxene Na and Zn contents and enhanced Mg#, Cr, Sr, REE, Pb, Th, U, and Cu.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011922","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143564603","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":"Large Igneous Province Sulfur Emissions Have Long-Term (>1000 Years) Effects on the Ocean Carbon Cycle","authors":"Hee Jun Cheong,&nbsp;Tushar Mittal,&nbsp;Courtney Jean Sprain,&nbsp;Isabel M. Fendley","doi":"10.1029/2024GC011893","DOIUrl":"https://doi.org/10.1029/2024GC011893","url":null,"abstract":"<p>Large Igneous Province (LIP) eruptions are thought to have driven environmental and climate change over wide temporal scales ranging from a few to thousands of years. Since the radiative effects and atmospheric lifetime of carbon dioxide (CO₂, warming) and sulfur dioxide (SO₂, cooling) are very different, the conventional assumption has been to analyze the effects of CO₂ and SO₂ emissions separately and add them together afterward. In this study, we test this assumption by analyzing the joint effect of CO₂ and SO₂ on the marine carbonate cycle using a biogeochemical carbon cycle box model (Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model). By performing model runs with very fine temporal resolution (∼0.1-year timestep), we analyze the effects of LIP carbon and sulfur gas emissions on timescales ranging from an individual eruption (hundreds to thousands of years) to the entire long-term carbon cycle (&gt;100,000 years). We find that, contrary to previous work, sulfur emissions have significant long-term (&gt;1,000 years) effects on the marine carbon cycle (dissolved inorganic carbon, pH, alkalinity, and carbonate compensation depth). This is due to two processes: the strongly temperature-dependent equilibrium coefficients for marine carbonate chemistry and the few thousand-year timescale for ocean overturning circulation. Thus, the effects of volcanic sulfur are not simply additive to the impact of carbon emissions. We develop a causal mechanistic framework to visualize the feedbacks associated with combined carbon and sulfur emissions and the associated timescales. Our results provide a new perspective for understanding the complex feedback mechanisms controlling the environmental effects of large volcanic eruptions over Earth history.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011893","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554506","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":"Petrology and Geochemistry of Ophiolitic Pyroxenite in the Eastern Desert of Egypt: Genesis of Ultramafic Cumulates and Implications for Neoproterozoic Supra-Subduction Seafloor Metamorphism","authors":"Hussam A. Selim,&nbsp;Paul D. Asimow,&nbsp;Ayman E. Maurice,&nbsp;Mohamad A. Ismail,&nbsp;Oliver D. Wilner,&nbsp;Nathan F. Dalleska,&nbsp;Moustafa E. Gharib,&nbsp;Safinaz A. A. Mahmoud","doi":"10.1029/2024GC011686","DOIUrl":"https://doi.org/10.1029/2024GC011686","url":null,"abstract":"<p>We describe and compare two outcrops of pyroxenite associated with Neoproterozoic ophiolite sequences in the Eastern Desert of Egypt: small masses in the Abu Samuki area of the North Eastern Desert and large belts in the Wadi El-Mireiwa area of the South Eastern Desert. This study presents field observations, petrographic descriptions, and data on mineral and whole-rock compositions as a basis for investigating the tectonic setting, nature, origin, and alteration history of this pyroxenite. Both pyroxenite bodies represent cumulates from the crustal sections of fragmented ophiolites, emplaced by thrusting above metasedimentary rocks and island arc assemblages, and later intruded by granite. Samples from both localities are mainly olivine clinopyroxenite. The compositions of olivine (Fo ∼ 79.7 and 0.13–0.49 wt% NiO), clinopyroxene, and fresh Cr-spinel cores, as well as the low whole rock Mg# (average 87.6 at Abu Samuki and 85.7 at Wadi El-Mireiwa) are all consistent with a cumulate origin for both pyroxenite suites. Moreover, the geochemical data all indicate that both pyroxenite suites are derived from fragments of oceanic lithosphere that developed in a fore-arc supra-subduction zone environment. The differences in mineral chemistry between the two locations suggest that the parental magma at Abu Samuki was low-Ti fore-arc basalt, while that at Wadi El-Mireiwa was a high-Ca boninite. The existence of green spinel, zoisite, Al-amphibole, pumpellyite and Mg-chlorite as secondary minerals in pyroxenite at Abu Samuki can be attributed to alteration and metasomatism by Al-Mg-Ca-bearing hydrothermal fluids. The preservation of deformation features in clinopyroxene and the absence of K-bearing secondary minerals suggest that this alteration was associated with circulation of seawater in fractured oceanic crust during the pre-obduction stage of ophiolite emplacement and not with the post-obduction granitoid intrusion.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011686","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554642","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":"Spatial Heterogeneity of Terrestrial Organic Carbon Burial and Degradation in the East Siberian Arctic Shelf Area","authors":"Yifang Sun,&nbsp;Jiazong Du,&nbsp;Limin Hu,&nbsp;Yuying Zhang,&nbsp;Jun Ye,&nbsp;Chuanzhen Zhu,&nbsp;Gang Yang,&nbsp;Yuriy Vasilenko,&nbsp;Alexander Bosin,&nbsp;Anatolii Astakhov,&nbsp;Ruediger Stein,&nbsp;Xuefa Shi","doi":"10.1029/2024GC011775","DOIUrl":"https://doi.org/10.1029/2024GC011775","url":null,"abstract":"<p>Climate warming has led to the translocation of a large amount of terrestrial organic carbon (TerrOC) into the Arctic Ocean. The fate of TerrOC varies dramatically in the Arctic shelves, thus introducing uncertainty into the climate-carbon feedback. In this study, we analyzed total organic carbon (TOC), stable organic carbon isotopes (<i>δ</i>¹³C) and lignin to investigate the spatial heterogeneity of sources and degradation of sedimentary OC on the East Siberian Arctic Shelf (ESAS). Furthermore, we also compared the cross-shelf degradation of TerrOC between the ESAS and Beaufort Shelf. High lignin content (0.51–2.25 mg/100 mg OC) and relatively depleted <i>δ</i>¹³C (−27.47‰ to −25.72‰) indicate that sedimentary OC in the nearshore areas of Laptev Sea and East Siberian Sea is predominantly of terrestrial origin, while in the rest area of the ESAS, the contribution of marine OC plays a dominant role in the OC burial. The distribution results of OC loadings and degradation proxy (3,5-Bd/V) suggest that OC supply is the main factor controlling the nearshore distribution of OC loadings. The simultaneous decrease of OC loadings (from 1.44 to 0.15 mg/m²) and increase of 3,5-Bd/V (from 0.04 to 0.73) indicate that TerrOC degradation could be an important mechanism controlling the offshore decrease of OC. Compared to the broad ESAS, although the inherent characteristics of the TerrOC sources could not be ignored, the inconspicuous variations in lignin content and degradation proxy in the narrow Beaufort Shelf may indicate that the shelf width could be an important factor influencing the offshore degradation of TerrOC.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011775","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554641","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":"On the Influence of Pressure, Phase Transitions, and Water on Large-Scale Seismic Anisotropy Underneath a Subduction Zone","authors":"John Keith Magali,&nbsp;Christine Thomas,&nbsp;Estelle Elisa Ledoux,&nbsp;Yann Capdeville,&nbsp;Sébastien Merkel","doi":"10.1029/2024GC011827","DOIUrl":"https://doi.org/10.1029/2024GC011827","url":null,"abstract":"<p>Seismic anisotropy mainly originates from the crystallographic preferred orientation (CPO) of minerals deformed in the convective mantle flow. While fabric transitions have been previously observed in experiments, their influence on large-scale anisotropy is not well-documented. Here, we implement 2D geodynamic models of intra-oceanic subduction coupled with mantle fabric modeling to investigate the combined effect of pressure <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>P</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(P)$</annotation>\u0000 </semantics></math>-and water-dependent microscopic flow properties of upper mantle and upper transition zone (UTZ) minerals, respectively, on large-scale anisotropy. We then compare our anisotropy models with anisotropic tomography observations across the Honshu subduction zone. Our results for the upper mantle correlate well with observations, implying that the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>P</mi>\u0000 </mrow>\u0000 <annotation> $P$</annotation>\u0000 </semantics></math>-dependence of olivine fabrics is sufficient to explain the variability of anisotropy. Meanwhile, a dry UTZ tends to be near-isotropic whereas a relatively wet UTZ could produce up to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> $1%$</annotation>\u0000 </semantics></math> azimuthal and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>2</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> ${sim} 2%$</annotation>\u0000 </semantics></math> radial anisotropy. Because water facilitates CPO development, it is therefore likely a requirement to explain the presence of anisotropy in the transition zone close to subducting slabs.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011827","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554507","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":"Research on the Closure Polarity of the Paleo-Asian Ocean: Evidence From the Three-Dimensional Lithospheric Resistivity Structure of Central Asian Orogenic Belt","authors":"Kejie Yang,&nbsp;Gaofeng Ye,&nbsp;Xiangcheng Yi,&nbsp;Zhiguo An,&nbsp;Sheng Jin,&nbsp;Bin Liang,&nbsp;Hao Dong","doi":"10.1029/2024GC011938","DOIUrl":"https://doi.org/10.1029/2024GC011938","url":null,"abstract":"<p>The Central Asian Orogenic Belt (CAOB) is a Phanerozoic accretionary orogen with a complex formation process. This study imaged the three-dimensional electrical structure of the lithosphere using the magnetotelluric data collected covering the southern margin of the CAOB. The resistivity model shows alternating high and low resistivities along the southern margin of the CAOB in the north, with the low resistivities in the middle and lower crust interpreted as remnants of the subducted crust of the Paleo-Asian Ocean (PAO). The belt-like low-resistivity body encased by high-resistivity bodies on both sides is interpreted as residual back-arc oceanic crust. The Alxa Block (AB) in the south exhibits overall high-resistivity characteristics, but a large low-resistivity area exists near the southeastern connection to the Ordos block. Based on the characteristics of the resistivity model, we propose that the final closure position of the PAO in the southern margin of the CAOB is the Enger Us fault zone, with a north-south bidirectional subduction mode. The widespread low-resistivity anomaly near the Badain Jaran fault zone is interpreted as residual subduction of the back-arc oceanic crust. The subduction of the PAO is a typical “trench-arc-basin” model. The variation in the subduction angle of the PAO along the strike may indicate that the later stage of the southern margin of the CAOB was subjected to the convergence effect of northeast-directed stress from the northeast margin of the Tibetan Plateau and the associated tectonic activities.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011938","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535790","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 Rare Glimpse of Paleoproterozoic Sub-Arc Mantle: The Ussuit Peridotite, West Greenland","authors":"T. McIntyre,&nbsp;P. Waterton,&nbsp;L. Li,&nbsp;B. Gong,&nbsp;X. Zha,&nbsp;K. Szilas,&nbsp;D. G. Pearson","doi":"10.1029/2024GC011928","DOIUrl":"https://doi.org/10.1029/2024GC011928","url":null,"abstract":"<p>Mantle residues beneath Archean cratonic nuclei have been extensively studied, whereas less attention has been given to the mantle lithosphere beneath Proterozoic mobile belts that link these nuclei. Rare mantle tectonites within tectonic mélanges of Paleoproterozoic mobile belts provide information important to understanding the broader processes involved in the construction of the cratonic mantle lithosphere. Here we present mineral compositions, bulk-rock major, trace, and platinum group elements, Re-Os isotopes, and olivine oxygen isotopes from a Paleoproterozoic mantle tectonite in West Greenland–the Ussuit peridotite. The Ussuit peridotite was emplaced in the crust during the Nagssugtoqidian orogeny between 1,870 Ma and 1,775 Ma and preserves primary melt depleted characteristics that reflect &gt;30% melting, for example, Al₂O₃ &lt; 0.4 wt.%, Ti &lt; 10 ppm, Lu/Yb &gt; 0.25, and Mg #s up to 93. Cryptic signatures of hydrous melting, for example, spinel Cr #’s &gt;65, Os/Ir ratios between 0.3 and 6, and supramantle olivine δ¹⁸O values, suggest that the high degree of melt depletion was partly inherited from a forearc or sub-arc melting environment. Re-Os isotopic systematics show melt depletion occurred at ∼2 Ga overlapping the juvenile oceanic arc crust that hosts the peridotites. This age coincides with a peak in the global production of juvenile cratonic lithosphere. Furthermore, the global Paleoproterozoic cratonic mantle has strong geochemical similarities with the Ussuit peridotites. It is suggested that subduction zone peridotites form key components of the Paleoproterozoic cratonic lithospheric mantle, creating a viscous, buoyant mantle lithosphere that contributed to the long-term stability of the greater cratonic masses.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011928","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535789","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":"Records of Chemical Weathering and Plateau Saline Lake Sediments Linked to Paleoclimate Fluctuations During the Eocene","authors":"Peng Pang,&nbsp;Xiucheng Tan,&nbsp;Kunyu Wu,&nbsp;Songtao Wu,&nbsp;Haoting Xing,&nbsp;Menglin Zhang,&nbsp;Na Zhang,&nbsp;Wei Deng","doi":"10.1029/2025GC012171","DOIUrl":"https://doi.org/10.1029/2025GC012171","url":null,"abstract":"<p>Interactions between mountain building, weathering and climate draw significant attention within the geoscience community. In this study, the mixed rocks from the Eocene Lower Ganchaigou Formation (LGCG) of the Qaidam Basin are employed for weathering intensity evaluation by petrology, mineralogy, and geochemistry. Lithological characteristics indicate high-frequency sedimentary cycles (&lt;10 m) of the LGCG mixed rocks, which are identified by a single cycle with four lithofacies from bottom to top: massive sandstones, laminated silty shales, laminated silty limestones, and bedded dolomites. Provenance analysis suggests a predominant felsic volcanic source within a continental island arc background for these mixed sediments. Chemical weathering intensity indices (CIA, chemical index of weathering, and plagioclase index of alteration) show a high coherence with sedimentary cycles, initially increasing and gradually decreasing in a single cycle. Chemical index of alteration values ranged from 51.1% to 67.2%, indicating weak to moderate weathering intensity. Additionally, correlation analysis reveals that the cyclical variations of chemical weathering intensity correlate strongly with regular paleoclimate evolution and terrigenous input changes, which were controlled by the shift of the westerlies. During the westerly strengthening periods, stronger precipitation results in a warm and humid paleoclimate conditions, leading to higher terrigenous input dominated by fine-grained clay minerals with moderate chemical weathering intensity. During the westerly weakening periods, less rainfall leads to a cold and dry paleoclimate conditions, resulting in lower terrigenous input dominated by coarser clastic sediments and weak weathering intensity. Our study provides new evidence and insights into the westerly shift and paleoclimate evolution in the Eocene from the perspective of high-resolution chemical weathering records.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012171","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535792","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":"Geochemical and Thermal Constraints on the Hikurangi Subduction Zone Hydrogeologic System and Its Role in Slow Slip","authors":"I. Aylward,&nbsp;E. A. Solomon,&nbsp;M. E. Torres,&nbsp;R. N. Harris","doi":"10.1029/2024GC011778","DOIUrl":"https://doi.org/10.1029/2024GC011778","url":null,"abstract":"<p>Fluid generation and migration regulate the development of pore fluid pressure, which is hypothesized to influence the occurrence of slow slip events at subduction zones. Seafloor seep sites present the opportunity to directly sample fluids flowing through the accretionary wedge and assess the hydrogeologic conditions of the outer forearc. We present heat flow measurements and pore water geochemistry from sediment cores collected at fault-hosted seep sites on the southern and northern Hikurangi margin, offshore the North Island of New Zealand. These measurements span the deformation front to the shelf break. Along the northern margin, heat flow data do not show anomalies that can be obviously attributed to the discharge of warm fluids. Pore fluid compositions indicate that seep fluids originate from compaction within the uppermost wedge. Reactive-transport modeling of pore water solute profiles produces fluid flow rate estimates ≤2 cm/yr. Shallow fluid sources and low discharge rates at offshore fault-hosted seeps suggest that the sampled fault zones are characterized by low permeability at depth, preventing efficient drainage of the megathrust and underthrust sediments to the seafloor. These results provide additional evidence that the northern Hikurangi margin plate boundary is associated with high pore fluid pressures that likely act as a control on slow slip activity.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011778","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497400","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":"Thermo-Tectonic History of Archean Basement Rocks in the Aktash Tagh, Southeastern Tarim Craton: Constraints From Zircon U-Pb, Zircon and Apatite Fission-Track Dating","authors":"Xiao Hu,&nbsp;Zhiyuan He,&nbsp;Ganqing Xu,&nbsp;Johan De Grave,&nbsp;Rongfeng Ge,&nbsp;Guangwei Li,&nbsp;Wenbin Zhu","doi":"10.1029/2024GC011483","DOIUrl":"https://doi.org/10.1029/2024GC011483","url":null,"abstract":"<p>Stable craton lithosphere can undergo complex tectonic events at its margins due to peripheral tectonic activity. In this study, we conducted a comprehensive analysis of zircon U-Pb dating, apatite and zircon fission-track thermochronology on the Aktash Tagh complex in the southeastern margin of the Tarim Craton. The obtained apatite fission-track ages range from ∼219 Ma to ∼104 Ma, while the zircon fission-track ages span from ∼1,400 Ma to ∼100 Ma. The zircon U-Pb ages from double dating of 261 grains range from ∼3.6 Ga to ∼1.9 Ga. The complexity of our zircon fission-track ages is attributed to the presence of both high-retentive zircons and low-retentive zircons. High-retentive zircons indicate that the samples have not been exposed to temperatures above the zircon fission-track reset temperature (∼350°C) since about 1.0 Ga. We can identify in the study area reheating events at ∼2.0–1.9 Ga and post 1.4 Ga, as well as cooling events at ∼1.9–1.8 Ga, ∼1.4 Ga, and ∼1.0 Ga. We conducted inverse thermal history modeling using QTQt software that revealed two significant thermo-tectonic events: (a) rapid rock cooling during the Middle to Late Jurassic, and (b) renewed rapid cooling from the Oligocene to the present day. The former cooling event may have been related to the collision between the Lhasa Block and the southern margin of Asia, while the latter is generally linked to the far-field effects of the India-Eurasia collision.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011483","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497401","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}