Geoscience frontiers最新文献

{"title":"A thickening event of the continental lithosphere ca. 2.2 billion years ago revealed by Nb/Ta-Dy/Yb systematics in basaltic rocks","authors":"Yu Zhang ,&nbsp;He Liu ,&nbsp;Yiran Wang ,&nbsp;Qian Chen ,&nbsp;Chen Chen ,&nbsp;Junjie Zhang ,&nbsp;Jing Fang ,&nbsp;Lipeng Zhang ,&nbsp;Wei-dong Sun","doi":"10.1016/j.gsf.2024.101993","DOIUrl":"10.1016/j.gsf.2024.101993","url":null,"abstract":"<div><div>Continental lithosphere thickness significantly influences Earth’s tectonic style, the stabilization of cratons, the compositions of intraplate volcanic rocks, and specific types of metallogenesis. Although the Archean cratons currently boast the thickest lithosphere among Earth’s continents, the evolution of its thickness throughout geological history remains inadequately comprehended. Intraplate small-volume volcanoes, typical products of magmatic activities within continents with thick lithosphere on the modern Earth, were rarely observed until the early Paleoproterozoic, possibly due to the high mantle temperature and insufficient thickness of the continental lithosphere. Here we show that the modern intraplate continental basalts exhibit distinctive signatures of both elevated Nb/Ta and Dy/Yb ratios, setting them apart from basalts found in arc, rift, and plume settings. Our statistical analysis of a geochemical database of basalts worldwide spanning the past 3.5 billion years indicates that modern-like intraplate continental basalts have become extensive since ca. 2.2 Ga. We attribute the emergence of intracontinental basalts to a lithospheric thickening event within the Archean craton continents, resulting from horizontal compression of the lithosphere during the assembly of the Nuna supercontinent.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101993"},"PeriodicalIF":8.5,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Ore geology, mineralogy and geochemistry of a fault-controlled hydrothermal clay-Li deposit hosted by Precambrian metasedimentary rocks in south China","authors":"Chunlong Wang ,&nbsp;Shaoyong Jiang ,&nbsp;Hanlie Hong ,&nbsp;Wei Wang ,&nbsp;Songlin Wan ,&nbsp;Wensheng Zhang ,&nbsp;Jin Yin","doi":"10.1016/j.gsf.2024.101992","DOIUrl":"10.1016/j.gsf.2024.101992","url":null,"abstract":"<div><div>The Jinyinshan-Huangdi′nao Li deposit (12,000 t Li₂O @ 0.60%) was recently discovered in southern Hubei Province, South China. This deposit is divided into two ore sections, namely, Jinyinshan (0.24–1.32 wt.% Li₂O) and Huangdi′nao (0.20–0.47 wt.% Li₂O). The dominant Li-bearing phase and mechanism for Li enrichment remain unclear. Herein, a comprehensive study of ore geology, mineralogy and geochemistry is conducted. Field and petrographic investigations revealed that Li mineralization in the deposit was fault-controlled and that the altered metasedimentary rocks and hydrothermal veins with intensive Li mineralization contained high abundances of Li-rich clay minerals. Whole-rock XRD and <em>in situ</em> analyses of SEM-EDS, EMPA and LA-ICP-MS of clay minerals reveal that cookeite (0.99–2.80 wt.% Li₂O) is the dominant Li-bearing phase, with subordinate illite (0.02–0.57 wt.% Li₂O). The widespread replacement of Li-enriched illite by cookeite combined with the compositional continuum suggests that cookeite was likely formed by the hydrothermal replacement of illite at a temperature of 240–270 °C, as constrained by chlorite geothermometry (with average temperatures of 254 ± 2 °C in Jinyinshan and 259 ± 2 °C in Huangdi′nao). Since metasedimentary rocks of the Neoproterozoic Lengjiaxi Group in the deposit with variable Li anomalies host abundant Li-rich illite, Li mineralization was inferred to have occurred via hydrothermal metasomatism of these clay-rich clastic rocks. The hydrothermal fluids may have been driven by a deep magmatic heat source, as evidenced by previously reported U-Pb dating of apatite from the clay-Li ore, similar to the age of the Mufushan granitic batholith in the south, both of which are Early Cretaceous. The deep-sourced hydrothermal fluids caused the mobilization, migration and reprecipitation of Li as Li-rich clays along the fault zones. This mechanism of Li mineralization is different from existing models for clay-Li deposits worldwide, and this deposit can be classified as a new type, namely, fault-controlled hydrothermal metasomatic clay-Li deposit. Similar deposits are highly prospective both regionally and worldwide.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101992"},"PeriodicalIF":8.5,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Strategies towards robust interpretations of Pb isotopes","authors":"J. Liebmann ,&nbsp;B. Ware ,&nbsp;A. Zametzer ,&nbsp;C.L. Kirkland ,&nbsp;M.I.H. Hartnady","doi":"10.1016/j.gsf.2024.101989","DOIUrl":"10.1016/j.gsf.2024.101989","url":null,"abstract":"<div><div>Lead (Pb) isotopes can provide key information to address fundamental geologic problems related to the formation and evolution of rocky planets. The Pb isotope system supports a diversity of applications, as it provides access to information on magma sources as well as geologic age. Consequently, a wide range of analytical techniques, data validation and interpretation strategies have been advanced across a range of Pb isotope studies. Given the multiple different Pb isotope pairs, reflecting different decay rates and ultimate parental isotope concentrations, Pb isotopes have been viewed as one of the more challenging isotope systems to comprehend. Here we provide an overview of the various analytical and interpretative approaches, for this system, and highlight their respective strengths in the context of applications, such as magma source tracking and model age determination. A discussion of different methods to determine magma source parameters (e.g., U/Pb ratio and model age) is presented, along with recommendations for data validation and reporting. A checklist for recommended data and metadata to report for Pb isotopes is provided. The aim of this contribution is to provide a framework that enables a robust interpretation of Pb isotope signatures, promoting data transparency and comparison across different analytical approaches.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101989"},"PeriodicalIF":8.5,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Neoarchean-Paleoproterozoic metallogenesis associated with plate tectonics in early Earth: Insights from the North China Craton","authors":"Tao Zeng ,&nbsp;Li Tang ,&nbsp;M. Santosh ,&nbsp;Hanhui Wang","doi":"10.1016/j.gsf.2024.101990","DOIUrl":"10.1016/j.gsf.2024.101990","url":null,"abstract":"<div><div>Precambrian cratons are archives of several precious metallic deposits that significantly contribute to our planet’s resources and habitability and also provide key information on plate tectonics on Earth. The North China Craton (NCC) preserves important records of Neoarchean to Paleoproterozoic tectonic processes and associated episodes of metallogenic pulses that generated five major types of mineral deposits including banded iron formations (BIFs), volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, orogenic Au deposits, magmatic sulfide Cu-Ni deposits and porphyry Cu deposits. These deposits are distributed in Neoarchean granite-greenstone belts and Paleoproterozoic orogenic belts, and show dominant mineralization ages of 2.6–2.5 Ga and two subordinate age groups of 2.7–2.6 Ga and 2.3–1.95 Ga. The Neoarchean metallogenic events generated BIFs, VMSs, Au and magmatic sulfide Cu-Ni deposits and the tectonic framework correlates with the microblock amalgamation and plate subduction possibly also aided by mantle plumes. The BIFs representing the dominant mineral deposits in Neoarchean are mainly Algoma-type with few examples of Superior-type. Meta-basaltic rocks associated with the Algoma-type BIF deposits in the granite-greenstone belts of the NCC display highly variable trace element compositions and LREE-depleted and LREE-enriched. The REE distribution patterns and high field-strength element characteristics of <em>meta</em>-basaltic rocks suggest the formation of BIF and VMS deposits in mid-ocean ridge, island arc and back-arc settings. The formation of VMS, Au and magmatic Cu-Ni deposits correspond to plate subduction and collision in a convergent continental margin setting during the late Neoarchean. The Paleoproterozoic deposits are represented by BIFs and porphyry Cu deposits. The Paleoproterozoic BIFs and <em>meta</em>-basaltic rocks correspond to magmatic-hydrothermal activities in passive continental margin or island arc settings, whereas the porphyry Cu deposits were formed in an extensional environment, corresponding to the Paleoproterozoic subduction-rifting events in the Trans-North China Orogen. The variation of <em>δ</em>⁵⁶Fe, Ce anomalies and Y/Ho ratios in BIFs from Neoarchean to Paleoproterozoic indicate the initial increase of oxygen in late Neoarchean and the change of ambient marine environment from anoxic to oxic during the Great Oxidation Event. The multi-stage Neoarchean to Paleoproterozoic metallogenic systems of the NCC were intrinsically linked to the plate subduction along with arc-plume interaction and rifting-subduction-collision activities. The contemporaneous increasing in weathering of exposed continental crust due to plate subduction potentially controlled the atmosphere-hydrosphere oxidation state and formation of BIF deposits in the NCC.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101990"},"PeriodicalIF":8.5,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 insight into seismotectonic scenario of the southwestern part of Delhi-NCR and delineation of new faults: Implications to seismic hazard potential","authors":"Sudipto Bhattacharjee ,&nbsp;Sanjay Kumar Prajapati ,&nbsp;Uma Shankar ,&nbsp;O.P. Mishra","doi":"10.1016/j.gsf.2024.101991","DOIUrl":"10.1016/j.gsf.2024.101991","url":null,"abstract":"<div><div>The southwestern region of the Delhi-National Capital Region (NCR) experiences sporadic micro (M ≤ 3.0) and occasional small (M &gt; 3.0) earthquakes with a seasonal influence. This study integrates remote sensing and seismological data to elucidate the seismotectonic scenario and identify potential unmapped faults. Analysis of DEM data (Cartoset) reveals numerous multidirectional minor faults, some coincident or conjugate to known major faults. Earthquake epicentres spatially correlate with several of these delineated faults. Fault plane solutions suggest a transition from central normal faulting to peripheral thrust faulting. Moment tensor decomposition indicates dominant double-couple mechanisms with significant non-double-couple components for earthquakes ranging from Mw 2.5 to 4.4. A major variation in principal stress orientation is apparent between the eastern and western regions of the study area. Stress inversion reveals a NW-SE shortening direction and unusual principal axis plunges, suggesting a rare “odd” or “unknown” faulting regime. These findings suggest ongoing rifting in the eastern Alwar basin may be inducing thrusting in the surrounding region along pre-existing Aravalli-Delhi fold belt thrusts. Seismogenesis likely results from a complex interplay of faulting, regional tectonics, and fluid interaction. This study highlights the value of a multidisciplinary approach for unravelling the intricacies of seismotectonic in low-to-moderate seismicity regions, with varying strengths due to diverse structural heterogeneity associated with mapped or unmapped (hidden) faults, which have been delineated in this study, as an additional information for assessing seismic hazard potential for Delhi-NCR.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101991"},"PeriodicalIF":8.5,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Black carbon aerosols impact snowfall over the Tibetan Plateau","authors":"Ye Zhou ,&nbsp;Junhua Yang ,&nbsp;Shichang Kang ,&nbsp;Yuling Hu ,&nbsp;Xintong Chen ,&nbsp;Mian Xu ,&nbsp;Mengmeng Ma","doi":"10.1016/j.gsf.2024.101978","DOIUrl":"10.1016/j.gsf.2024.101978","url":null,"abstract":"<div><div>Snowfall is the primary form of cold-season precipitation over the Tibetan Plateau (TP), crucial for the maintenance of glaciers and snow cover, affecting regional climates and water resources availability. Through an integrative analysis of observations, numerical simulations, and statistical analyses, we found that the spatiotemporal distribution of snowfall across the TP is significantly influenced by black carbon (BC) aerosols from South Asia and the TP. BC affects the snowfall process through multiple mechanisms. Specifically, BC significantly raises atmospheric temperature over the TP, thereby reducing snowfall, particularly in the central TP during autumn, with reductions reaching approximately − 9 mm water equivalent month⁻¹. Moreover, BC enhances cold-season moisture transport from the Bay of Bengal, increasing moisture flux in the southeastern TP and thereby augmenting snowfall in that area by up to 5 mm water equivalent month⁻¹. This study elucidates the complex impact of BC on the spatial–temporal snowfall patterns across the TP and provides important insights into the sustainable development of water resources in the region amid ongoing climate change.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101978"},"PeriodicalIF":8.5,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 unusual lunar origin and chondritic refractory Antarctic micrometeorites","authors":"D. Fernandes,&nbsp;N.G. Rudraswami","doi":"10.1016/j.gsf.2024.101975","DOIUrl":"10.1016/j.gsf.2024.101975","url":null,"abstract":"<div><div>We report unearthing the first silicate-type (S-type) lunar Antarctic micrometeorites (AMM) spherule and another spherule with a refractory chondritic phase. The lunar spherule is made of Augite with minor Ni magnetite (&lt;1 wt.%), in contrast to other known cosmic spherules. The Augite’s minor oxide range in the spherule are as follows: Wo_37-41En_25-27Fs_34-36, Al₂O₃: 0.7–1 wt.%, Cr₂O₃: 0.01–0.06 wt.%, MnO: 0.32–0.39 wt.% and TiO₂: 0.03–0.09 wt.%. The lunar spherule’s chemical characteristics indicate that it originated from very low Ti lunar basalt (VLT) mare basalts. Chondritic diopside (Wo_46-47En_50-47Fs_5-6, Al₂O₃: 1.7–1.6 wt.%, Cr₂O₃: 0.6–0.63 wt.%, MnO: 0.2–0.4 wt.%, and TiO₂: 0.0–0.02 wt.%) makes up the refractory phase in the second spherule. The chemical composition of diopside is indistinct from those of calcium aluminium inclusion (CAIs) found in both ordinary and carbonaceous chondrites. Our finding reveals that micron-sized lunar impact debris can potentially reach the Earth’s surface, similar to the earliest formed nebulae solid component.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101975"},"PeriodicalIF":8.5,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Satellite gravity fields and the identification of accreted microplates","authors":"C. Braitenberg ,&nbsp;G. Maurizio ,&nbsp;T. Pivetta ,&nbsp;A. Pastorutti ,&nbsp;W. Cavazza","doi":"10.1016/j.gsf.2024.101976","DOIUrl":"10.1016/j.gsf.2024.101976","url":null,"abstract":"<div><div>Small-scale lithospheric terranes (microplates) are important building-blocks of continental accretion but their presence is often obscured by subsequent plate-margin deformation events and by younger volcano-sedimentary covers. The geological fabric of the eastern Anatolian-Caucasian region results from the sequential accretion of lithospheric terranes against the southwestern continental margin of the Eurasian plate. Widespread sedimentary and volcanic covers conceal some of the principal tectonic boundaries in the region, and major uncertainties persist as to the number and extent of the various terranes.</div><div>We determine whether the topographic height fits the expectance from crustal thickness, complying to the isostatic equilibrium. The input data of the study are the topography, the satellite derived gravity field, the geologic knowledge defining magmatic intrusions and tectonic terranes, arcs and sedimentary basins, the seismic Moho depth, and a seismic tomography model. We accomplish a topography-gravity regression analysis controlled by a seismic Moho model, which produces well defined positive and negative anomalies. Allowing for varying density contrast in lower crust, the topography is greatly in isostatic equilibrium and controlled by the crustal thickness, that is topographic uplift has evolved proportionally to crustal thickening. The average density contrast in lower crust is between 200 and 300 kg/m³ for the orogenic belt, with local exceptions.</div><div>The inversion of the prominent positive linear anomalies of the regional gravity field defines discrete crustal density inhomogeneities, which can be interpreted as related to specific tectonic events, thus placing cogent constraints on the accretionary history and the overall anatomy of the eastern Anatolian-Caucasian lithospheric agglomerate. Three linear belts of intracrustal increased density are found along (i) the Greater Caucasus, (ii) the Lesser Caucasus, and (iii) a previously unidentified parallel belt ca. 80 km south of the Lesser Caucasus. The latter gravity anomaly clearly delineates for the first time the southwestern margin of the South Armenian Block, a lithospheric element (microplate) whose existence has long been a matter of debate.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101976"},"PeriodicalIF":8.5,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Timing of syn-orogenic extension in the Western Alps revealed by calcite U-Pb and hematite (U-Th)/He dating","authors":"Antonin Bilau ,&nbsp;Yann Rolland ,&nbsp;Stéphane Schwartz ,&nbsp;Cécile Gautheron ,&nbsp;Thierry Dumont ,&nbsp;Dorian Bienveignant ,&nbsp;Benjamin Brigaud ,&nbsp;Nicolas Godeau ,&nbsp;Abel Guihou ,&nbsp;Pierre Deschamps ,&nbsp;Xavier Mangenot ,&nbsp;Marianna Corre ,&nbsp;Rosella Pinna-Jamme ,&nbsp;Nathaniel Findling","doi":"10.1016/j.gsf.2024.101969","DOIUrl":"10.1016/j.gsf.2024.101969","url":null,"abstract":"<div><div>Understanding fault activity over time provides valuable insights for reconstructing the tectonic history of an orogen, assessing seismological risks and understanding mineralization processes. In the Western Alps, one of the main controversies in existing tectonic models is the understanding of <em>syn</em>-orogenic extension. Seismological evidence shows widespread extensional deformation related to the reactivation of major lithospheric structures, such as the Penninic Frontal Thrust (PFT). However, the onset age and origin of extension are still debated due to the lack of suitable geochronological data. Fault hematite and calcite geochronology as well as clumped isotope data can be used to relate fluid regimes to fault activity. The analysis of calcite brecciae from extensional faults above the PFT shows that two distinct fluid regimes were present. The first regime, occurring before 2 Ma is associated with upwelling of deep fluids and is recorded by fault calcite at a temperature &gt; 110°C. The second fluid regime is characterized by a meteoric signature and temperatures around 36 °C, representing crystallization since 2 Ma. This study presents a new model for the Miocene tectonic history of the Western Alps that combines (U-Th)/He and U-Pb geochronology on fault hematite (13.3 ± 0.8 to &lt; 0.8 Ma) and calcite (5.3 ± 0.6 Ma). Results demonstrate a progression of extensional fault activity from east to west, from the Middle Miocene (ca. 13 Ma) to the Quaternary. The onset of extension in the inner part of the belt coincides with the development of the fold and thrust belt in the western Alpine foreland. Our new model proposes that extension occurs in the hanging wall of a large top-to-the-west thrust, known as the Alpine Frontal Thrust. This thrust, located to the west of the External Crystalline Massifs gives rise to their uplifting and extension at the rear.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101969"},"PeriodicalIF":8.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"High-resolution astronomical records of shale strata in faulted lake basins and implications for the sedimentary process of laminated sediments","authors":"Xianzheng Zhao ,&nbsp;Xiaoping Liu ,&nbsp;Huan Liu ,&nbsp;Fengming Jin ,&nbsp;Xiugang Pu ,&nbsp;Biao Sun ,&nbsp;Zhannan Shi","doi":"10.1016/j.gsf.2024.101974","DOIUrl":"10.1016/j.gsf.2024.101974","url":null,"abstract":"<div><div>Lamina structure, a typical feature of shale, has significant implications for hydrocarbon generation, shale oil and gas reservoir evaluation, and palaeoenvironmental studies. In this study, we conducted a high-resolution astronomical analysis of shale strata from the Kongdian Formation in the Cangdong Sag, Bohai Bay Basin, China, and performed macroscopic and microscopic textural characterization of core samples. The time series analysis of the G108-8 Well indicates that stratigraphic cycles of 113.2–25.3 m, 12.7–7.8 m, 4.7–2.7 m, and 2.3–1.3 m are controlled by long eccentricity, short eccentricity, obliquity, and precession, respectively. The sedimentary accumulation rate (SAR) is estimated to be approximately 20.3 cm/kyr. The core description reveals that Ek₂ primarily consists of laminated shale with individual laminae less than 1 cm in thickness. Using a polarizing microscope, the average thickness of a single lamina is approximately 250 μm, with most laminae being less than 400 μm. We constructed a time-depth model for lacustrine laminated sediments and compared it with other ancient lacustrine strata and modern lakes. The sediment accumulation rate of ancient lacustrine strata ranges from 1.3 to 20.3 cm/kyr. The sedimentation rate of shale and the thickness distribution of individual laminae provide evidence for the annual nature of the lamina couplets. Finally, we propose a simplified model to illustrate the sedimentation process, emphasizing the record of laminated sediments in semi-deep to deep facies. Our results contribute to the understanding of lacustrine sedimentary processes, laminated sedimentary records, organic matter enrichment processes, palaeoenvironments, and their potential relationships.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 2","pages":"Article 101974"},"PeriodicalIF":8.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}