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Geochemical composition and grain size of surface sediments from reticulate dunes in the Tengger Desert, China 腾格里沙漠网状沙丘表层沉积物的地球化学组成和粒度特征
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-28 DOI: 10.1016/j.sedgeo.2025.106851
Junguang Wang , Zhibao Dong , Zhengcai Zhang , Rongliang Liu , Jiqiao Shi , Ping Lü
Reticulate dunes are the prevalent type of dunes found in deserts worldwide. However, compared to other dune types, systematic research on reticulate dunes remains limited, and aspects such as their formation mechanisms, grain size characteristics, and elemental composition characteristics remain inadequately understood. This study integrated regional wind regime data to analyse the grain size characteristics of reticulate dunes (specifically, the primary and secondary ridges) in the Tengger Desert, Considering both primary and sub-wind seasons. Additionally, we examined the elemental composition characteristics and degree of weathering of these dunes. The results indicate that the primary and secondary ridges of the reticulate dunes in the Tengger Desert are predominantly composed of fine sand and very fine sand with a mean grain size of 2.52Φ. Compared with other deserts in China and abroad, the sediments exhibit relatively finer grain sizes and better sorting. Furthermore, the grain size characteristics of surface sediments in the primary and secondary ridges exhibited two distinct distribution patterns during different wind seasons, indicating differences in the formation mechanisms of the primary and secondary ridges. The major elements in the surface sediments of the reticulate dunes in the Tengger Desert are SiO2 and Al2O3, while the predominant trace elements are primarily Ba, Sr, Zr, and Cr. This indicates that the geochemical composition of the sediments is influenced not only by the intrinsic characteristics of the elements but also by the regional climate and the supply of fresh materials, which are significant factors affecting their chemical behavior and content differences. The chemical weathering indices (CIA, residual coefficient, and ICV), along with the A-CN-K and A-CNK-FM triangular diagrams, suggest that the sedimentary environment of the reticulate dune sediments in the Tengger Desert is characterised by a cold, dry climate with a low degree of weathering. The weathering process occurs during the initial stages of plagioclase chemical weathering. These findings lay the foundation for further research on the formation mechanisms, evolutionary processes, and sedimentary environments of reticulate dunes, contributing to a deeper understanding of these complex geomorphological features.
网状沙丘是全球沙漠中最常见的沙丘类型。然而,与其他沙丘类型相比,对网状沙丘的系统研究还很有限,对网状沙丘的形成机制、粒度特征、元素组成特征等方面的认识还不够充分。本研究综合区域风况资料,分析了腾格里沙漠网状沙丘(主要是初级和次级山脊)的粒度特征,同时考虑了初级和次级风季。此外,我们还研究了这些沙丘的元素组成特征和风化程度。结果表明:腾格里沙漠网状沙丘的主垄和次垄以细沙和极细沙为主,平均粒径为2.52Φ;与国内外其他沙漠相比,沉积物粒度较细,分选效果较好。在不同风季,主次脊表层沉积物粒度特征呈现出两种截然不同的分布格局,说明主次脊形成机制存在差异。腾格里沙漠网状沙丘表层沉积物中元素含量以SiO2和Al2O3为主,微量元素以Ba、Sr、Zr和Cr为主,表明沉积物的地球化学组成不仅受元素本身特征的影响,还受区域气候和新鲜物质供应的影响,是影响其化学行为和含量差异的重要因素。化学风化指标(CIA、残余系数和ICV)及a - cn - k和a - cnk - fm三角图表明,腾格里沙漠网状沙丘沉积物的沉积环境为寒冷干燥、风化程度低的气候。风化过程发生在斜长石化学风化的初始阶段。这些发现为进一步研究网状沙丘的形成机制、演化过程和沉积环境奠定了基础,有助于对网状沙丘复杂的地貌特征有更深入的认识。
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引用次数: 0
The importance of sedimentary structures in fine-grained deposits in re-interpreting the Facies mosaic of Lower Triassic tide-influenced deltas 细粒沉积构造在重新解释下三叠统潮染三角洲相镶嵌中的重要性
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-27 DOI: 10.1016/j.sedgeo.2025.106850
Ibrahim Zallum
Despite considerable progress in their description and characterization, tide-dominated deltas remain the least understood of the three main delta classes. Fine-grained sediments of the deltaic subenvironments remain particularly understudied, especially via ultra-thin section analysis. Such analysis can aid in identifying subenvironments typically missed in paleodelta analysis (e.g., delta plains). Combined with other methods, they can prove valuable in evaluating depositional and sequence-stratigraphic models and exploring the interplay between sediment supply and channel morphologies.
This study focuses on the Lower Triassic Torrey Member of the Moenkopi Formation of southern Utah. Previous interpretations posit that the Torrey Member represents a tide-dominated delta deposited in three depositional sequences. Integrating mudstone thin section analysis helped reveal that the Torrey Member contains ten facies associations, with the facies architecture indicating deposition by tide-dominated or tide-influenced deltas over a single depositional sequence. The progradational phase is notable for its decreased channel density and concurrent increase in subaerial exposure indicators. This study posits that hyperycnal flows, including bedload transport, dominated deposition in the prodelta and delta front of the Torrey Member, with no direct evidence of tidal processes.
This study broadly demonstrates the importance of integrating mudstone thin-section analysis in paleodelta studies. This paper particularly draws particular attention to delta plain identification in semi-arid and arid settings and suggests that thin-section analysis may reveal examples previously missed in similar paleodeltas.
尽管在描述和表征方面取得了相当大的进展,但潮控三角洲仍然是三种主要三角洲类型中最不为人所知的。对三角洲亚环境的细粒沉积物的研究尤其不足,特别是通过超薄切片分析。这样的分析有助于识别古三角洲分析中通常遗漏的亚环境(例如三角洲平原)。与其他方法相结合,它们在评价沉积和层序地层模型以及探索沉积物供应与河道形态之间的相互作用方面具有重要价值。本研究以犹他州南部Moenkopi组下三叠统Torrey段为研究对象。以前的解释认为,托里段代表了一个潮汐控制的三角洲,沉积在三个沉积序列中。综合泥岩薄片分析揭示了托里段包含10个相组合,其相构型表明在单一沉积层序上沉积了潮汐控制或潮汐影响的三角洲。在渐积期,沟道密度下降,同时地面暴露指标增加。本研究认为,托里段前三角洲和三角洲前缘的沉积主要是高旋流,包括床质搬运,但没有潮汐作用的直接证据。该研究广泛地证明了泥岩薄片综合分析在古三角洲研究中的重要性。本文特别关注半干旱和干旱环境下的三角洲平原识别,并建议薄切片分析可能揭示以前在类似的古三角洲中遗漏的例子。
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引用次数: 0
Carbonate sedimentation and early diagenesis of the Doushantuo Formation, South China: A window into the terminal Proterozoic 华南陡山沱组碳酸盐沉积与早期成岩作用:研究末元古代的一个窗口
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-25 DOI: 10.1016/j.sedgeo.2025.106847
Min Ren
Precambrian marine carbonates with distinct sedimentary fabrics and structures provide valuable insights into the chemical and biological conditions of early oceans. To better understand shallow marine environments approaching the terminal Proterozoic, this study examines carbonate deposits from the Ediacaran Doushantuo Formation across the shoal-rimmed Yangtze platform in South China. These mimetically dolomitized rocks comprise facies of micropeloidal leiolite, grainstone-packstone, micropeloidal and microlaminated leiolites, stromatolite, and mudstone, representing a transition from the upper slope and platform margin environments to the back-shoal peritidal system. The grainstone-packstone facies features large intraclasts of incipient aragonite and high-Mg calcite cements, along with radial ooids that are <2 mm in diameter, all exhibiting varying degrees of microbial micritization. The peritidal facies, marked by abundant microbialites, are dominated by micropeloidal-microlaminated leiolites from the intertidal zone and stromatolites and dolomudstones from deeper waters. Abundant fibrous dolomites (fascicular and radial length-slow, up to 5 mm long) fill cavities in the peritidal facies, particularly within microbial mat cracks. Developed on a warm-temperate to tropical shelf, the rapid early lithification of Doushantuo sediments indicates a high degree of seawater supersaturation during the late Neoproterozoic compared to modern conditions. The remarkable diversity in the physical properties of the Doushantuo carbonates reflects an increased compartmentalization of processes governing carbonate formation and dissolution in shallow marine environments. This shift corresponds with the evolving chemical and biological conditions of the Precambrian ocean, which increasingly emphasized microbial roles in dolomite precipitation. By the terminal Proterozoic, platform carbonate formation became more susceptible to local fluctuations affecting saturation states and kinetic conditions, largely influenced by microbial activity.
具有独特沉积结构和结构的前寒武纪海洋碳酸盐岩为了解早期海洋的化学和生物条件提供了宝贵的见解。为了更好地了解接近元古代末期的浅海环境,本研究考察了中国南方浅滩边缘扬子台地埃迪卡拉系陡山沱组的碳酸盐岩沉积。这些模拟白云化岩石包括微球面扁纹岩相、颗粒岩-包覆岩相、微球面和微层状扁纹岩相、叠层石相和泥岩相,代表了从上斜坡和台地边缘环境到滩后潮外体系的过渡。颗粒岩-包岩相以早期文石和高镁方解石胶结物的大内碎屑为特征,具有直径约2 mm的放射状鲕粒,均表现出不同程度的微生物微晶化作用。潮旁相以潮间带的微球状-微层状平面岩和深水的叠层石和白云岩为主,微生物岩丰富。丰富的纤维状白云岩(束状和放射状长度缓慢,可达5毫米长)填充在潮滩相的空腔中,特别是在微生物席裂缝中。陡山沱组沉积发育在暖温带至热带陆架上,其早期快速的岩化作用表明,与现代条件相比,新元古代晚期的海水过饱和程度较高。陡山沱组碳酸盐岩物理性质的显著多样性反映了浅海环境下碳酸盐岩形成和溶解过程的分区化程度增强。这一转变与前寒武纪海洋化学和生物条件的演变相一致,微生物在白云岩降水中的作用日益受到重视。到元古代末期,台地碳酸盐岩地层更容易受到局部波动的影响,影响饱和状态和动力学条件,这在很大程度上受微生物活动的影响。
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引用次数: 0
Sedimentology of a drowned carbonate platform from the Sciacca area (southwestern Sicily): Insights into the Jurassic palaeogeography of Western Tethys 西西里岛西南部Sciacca地区溺沉式碳酸盐岩台地沉积学:西特提斯地区侏罗纪古地理研究
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-22 DOI: 10.1016/j.sedgeo.2025.106839
Francesca Petrella, Simona Todaro, Carolina D'Arpa, Attilio Sulli
A sedimentological-stratigraphic study of the Mesozoic carbonates exposed in two inactive quarries in southwestern Sicily has provided new insights into the palaeogeographic evolution of the southern sector of the Western Tethys margin during the Jurassic.
The Lower–Upper Jurassic succession consists of shallow-water peritidal carbonates, intersected by neptunian dykes and sills, which transition upwards into condensed pelagic limestone. Microfacies analysis of the shallow-water peritidal carbonates has led to their reassignment to the Hettangian–Pliensbachian (p.p.), previously attributed to the Late Triassic. Furthermore, variations in biodiversity within these stratigraphic horizons reflect the survival and recovery interval following the end-Triassic mass extinction event.
The abrupt transition to condensed pelagic limestone indicates the drowning of the carbonate platform. Lateral facies variations observed within the condensed pelagic limestone suggest different sedimentological processes, influenced by a complex system of structural highs and basins related to the Pangea continental rift. The presence of distinctive micro- and macrofacies, such as micritic oolites and FeMn hardgrounds, indicates a varied palaeotopographic setting for each section, where sedimentation is further controlled by bottom-current activity and low sedimentation rates.
对西西里岛西南部两个不活跃采石场中暴露的中生代碳酸盐岩进行沉积地层学研究,为西特提斯边缘南段侏罗纪时期的古地理演化提供了新的认识。下侏罗统-上侏罗统由浅水潮外碳酸盐岩组成,由海王星岩脉和岩台相交,向上过渡为凝聚的远洋灰岩。通过对浅水潮旁碳酸盐岩的微相分析,将其重新定位为hettangan - pliensbachian (p.p.),以前被认为是晚三叠世。此外,这些地层层位内生物多样性的变化反映了三叠纪末大灭绝事件后的生存和恢复间隔。向凝结的远洋灰岩的突然转变表明碳酸盐台地被淹没。在凝结的远洋灰岩中观察到的侧向相变化表明,受与盘古大陆裂谷有关的复杂构造高地和盆地系统的影响,沉积过程不同。不同微相和大相的存在,如泥晶鲕粒和FeMn硬岩,表明每个剖面具有不同的古地形背景,其中沉积进一步受到底流活动和低沉积速率的控制。
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引用次数: 0
Stratigraphic architecture of a multi-sourced, Deepwater lobe complex (early Permian, Paraná basin, Brazil) 巴西帕拉纳<e:1>盆地早二叠世深水多源叶状杂岩的地层构型
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-18 DOI: 10.1016/j.sedgeo.2025.106838
Sérgio Francisco Leon Dias , Fernando Farias Vesely , Ronaldo Paulo Kraft , Giovana Rebelo Diório , Guillan Diedrichs Fayad
The Rio Segredo Member of the Taciba Formation (Paraná Basin, Brazil) represents a unique example of a multi-sourced turbidite lobe complex, providing valuable insights into the stratigraphic architecture and depositional processes of delta-fed submarine ramp systems. This study investigates the lobe complex, which extends over 120 km and reaches a thickness of up to 40 m, with a focus on bed type distribution, facies associations, and stratigraphic architecture. Through the analysis of 16 measured sections and detailed facies analysis, 14 distinct bed types were identified, including turbidites (TBDs), hybrid event beds (HEBs), and slump and blocky flow deposits (MTDs). These beds are organized into four sub-environments: lobe axis, lobe off-axis, lobe fringe, and distal lobe fringe, reflecting a compensational stacking pattern with lobe centroids shifting southward by an average of 25 km. Paleocurrent data indicates predominant flow directions to the northwest (320°) and southwest (235°), supporting the interpretation of a multi-sourced system. The lobe complex is interpreted as a delta-fed submarine ramp, with deposition driven by delta-front instabilities and hyperpycnal flows via conduits connected to prograding delta. Hybrid event beds, which are common in the basal sandy portion of the succession, are linked to substrate erosion and interactions with small-scale morphological highs, highlighting the influence of paleophysiography on flow dynamics. This study enhances the understanding of multi-sourced turbidite systems and provides a framework for identifying similar systems in other basins. The findings underscore the importance of autogenic controls, such as lobe avulsion and topographic compensation, in shaping the stratigraphic architecture of delta-fed turbidite systems.
巴西帕拉南盆地Taciba组里约热内卢Segredo段是多源浊积叶状杂岩的一个独特例子,为三角洲海底斜坡系统的地层结构和沉积过程提供了有价值的见解。本研究对叶状复合体进行了研究,该复合体延伸超过120公里,厚度达40米,重点研究了床型分布、相组合和地层结构。通过对16个实测剖面的分析和详细的相分析,确定了14种不同的层型,包括浊积岩(TBDs)、混合事件层(HEBs)、滑塌和块状流沉积(MTDs)。这些地层被划分为4个亚环境:叶轴环境、叶离轴环境、叶边缘环境和远叶边缘环境,反映出叶中心向南移动平均25 km的补偿叠加格局。古海流资料显示,主要流向为西北(320°)和西南(235°),支持多源系统的解释。叶状复合体被解释为三角洲供给的海底斜坡,其沉积是由三角洲前缘的不稳定性和连接到推进三角洲的导管的超旋流驱动的。混合事件层在演替的基底砂质部分中很常见,它与基底侵蚀以及与小尺度形态高点的相互作用有关,突出了古地貌对流动动力学的影响。该研究增强了对多源浊积岩系统的认识,并为识别其他盆地的类似系统提供了框架。这些发现强调了自生控制的重要性,如裂片撕裂和地形补偿,在形成三角洲浊积体系的地层结构中。
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引用次数: 0
Depositional systems constraining the distribution of hydrothermal dolostone geobodies: A case study of Permian Guadalupian dolostone in the eastern Sichuan Basin 制约热液白云岩地质体分布的沉积体系——以川东二叠系瓜达鲁普系白云岩为例
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-18 DOI: 10.1016/j.sedgeo.2025.106837
Lu Shi , Ziye Lu , Fei Li , Hairuo Qing , Wenzhuo Jiang , Wei Li , Zenghua Li , Ning Ye , Bei Zhu , Qi Tang , Haizhou Qu , Yang Xiao , Shaonan Zhang
Lithological heterogeneity can be an important factor in regulating the spatial distribution of hydrothermal dolostone (HTD) geobodies. Understanding HTD genesis is crucial for improving our ability to predict subsurface HTD occurrence within sedimentary frameworks. This study investigates HTD development within the Permian Guadalupian carbonate successions of the eastern Sichuan Basin, China, providing significant insights into HTD formation processes. Through systematic sedimentological analysis of four outcrop sections (Fangniuba, Shangping, Tuotuoba, and Wuyangba), we identified eight distinct lithofacies and five lithofacies associations (LA1–LA5). Integrating field observations with data from adjacent sites, we performed a comprehensive evaluation of the depositional sequences, sedimentary environments, and petrophysical properties of the Guadalupian carbonate strata. These carbonates display a distinctive shallowing-upward sequence overlain by a deepening-upward succession. Notably, Guadalupian dolostones are consistently hosted within the middle portions of the shallowing-upward sequences across all studied sections. Petrological and mineralogical analyses further reveal preferential dolomitization in thin- to medium-bedded wackestone containing nodular cherts (LA2), which served as lateral conduits for hydrothermal fluid migration. Enhanced fracturing is observed within these lithologies, particularly along bedding planes and around nodular chert margins, reflecting their greater susceptibility to petrophysical modification. This preferential dolomitization reflects the interplay of carbonate texture, rock permeability, and fracture susceptibility, which collectively establish optimal diagenetic conditions for fluid-rock interaction. Our findings demonstrate that depositional lithological heterogeneity constrains HTD distribution through two key pathways: (1) primary lithological controls (including permeability variations and mud content), and (2) mechanically influenced properties (particularly bed thickness and nodular cherts). This heterogeneity, established during initial deposition to shallow-burial phases, fundamentally preconditioned subsequent HTD formation and distribution during later hydrothermal fluid emplacement.
岩性非均质性是影响热液白云岩(HTD)地质体空间分布的重要因素。了解HTD成因对于提高我们预测沉积格架中地下HTD产状的能力至关重要。本研究考察了中国四川盆地东部二叠系瓜达鲁普系碳酸盐岩地层中高温储层的发育情况,为研究高温储层的形成过程提供了重要的见解。通过对方牛坝、上坪、沱沱坝和五羊坝4个露头剖面的系统沉积学分析,确定了8个不同的岩相和5个岩相组合(LA1-LA5)。结合现场观测和邻近地区的数据,对瓜达鲁普系碳酸盐岩地层的沉积层序、沉积环境和岩石物理性质进行了综合评价。这些碳酸盐岩具有明显的浅—上序,上覆着深—上序。值得注意的是,在所有研究剖面中,瓜达鲁普系白云岩始终赋存于浅层向上层序的中部。岩石矿物学分析进一步揭示了含结核燧石(LA2)的薄至中层砾岩的优先白云化作用,为热液流体运移提供了横向通道。在这些岩性中,特别是沿层理面和结核状燧石边缘周围,观察到压裂作用增强,反映出它们对岩石物理改造的敏感性更高。这种优先白云化反映了碳酸盐结构、岩石渗透率和裂缝敏感性的相互作用,共同为流体-岩石相互作用创造了最佳成岩条件。我们的研究结果表明,沉积岩性非均质性通过两个关键途径限制了HTD的分布:(1)主要岩性控制(包括渗透率变化和泥浆含量),以及(2)机械影响性质(特别是层厚和块状燧石)。这种非均质性是在初始沉积阶段到浅埋藏阶段建立起来的,从根本上为后期热液侵位过程中HTD的形成和分布做好了准备。
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引用次数: 0
Paleosols as paleoclimate proxies to reconstruct mid-Cretaceous paleoclimate conditions in Central Patagonia, Argentina 古土壤作为古气候指标重建阿根廷中部巴塔哥尼亚中白垩世古气候条件
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-17 DOI: 10.1016/j.sedgeo.2025.106836
Sabrina Lizzoli , M. Sol Raigemborn , Augusto N. Varela , José M. Paredes
The paleosols preserved in the Bajo Barreal Formation in central Patagonia (Argentina) provide valuable insights into mid-Cretaceous paleoclimatic conditions at mid-paleolatitudes in the Southern Hemisphere. This study integrates macro-, micro-, and nanomorphological analyses, clay mineralogy, and geochemical data to characterize and classify the Bajo Barreal's paleosols and reconstruct their paleoclimate conditions. The Cerro Ballena anticline's exposure begins with isolated, small-scale channel belts of low connectivity within siliciclastic mudstones (Section A). Upwards, it transitions into sheet-like, interconnected channel-belt complexes interbedded with thinner volcaniclastic floodplain deposits (Section B). We identified four pedotypes in stratigraphic order of appearance: Cerro Guacho (vertic Alfisols-like paleosols), Cañadón Vasco (Vertisols-like paleosols), San Bernardo (Ultisols-like paleosols), and Río Deseado (hydromorphic Inceptisols-like paleosols). Section A contains smectite-rich vertic Alfisols-like paleosols and Vertisols-like paleosols formed under moderate weathering, dominated by argilluviation, vertization, hydromorphism, and calcification. Section B, in contrast, contains kaolinite-rich Ultisols-like paleosols and hydromorphic Inceptisols-like paleosols formed under intense weathering conditions, dominated by lixiviation (ferruginization) accompanied by argilluviation and hydromorphism. This progression reflects a transition from temperate and subhumid conditions with seasonal rainfall (Section A) to warmer (temperate) and humid conditions with perennial rainfall (Section B). This vertical progression parallels mid-Cretaceous global climate dynamics and potentially reflects changes near the Cenomanian–Turonian boundary and OAE 2, offering valuable contributions to refine Southern Hemisphere paleoclimate reconstructions.
巴塔哥尼亚中部Bajo Barreal组保存的古土壤为了解南半球中古纬度的中白垩世古气候条件提供了有价值的见解。本研究综合了宏观、微观和纳米形态分析、粘土矿物学和地球化学数据,对巴霍巴雷亚盆地的古土壤进行了表征和分类,并重建了古气候条件。Cerro Ballena背斜的出露始于硅质泥岩内孤立的、低连通性的小规模河道带(A段),向上过渡为片状的、相互连接的河道带复体,与较薄的火山碎屑冲积平原沉积物互层(B段)。Cerro Guacho(垂直alfsols -like古土壤),Cañadón Vasco(垂直alfsols -like古土壤),San Bernardo(类似Ultisols-like古土壤)和Río Deseado(水形态的类似Inceptisols-like古土壤)。A段含富蒙脱石的垂直Alfisols-like古土壤和中等风化作用下形成的垂直Alfisols-like古土壤,以泥化作用、垂直作用、水形态作用和钙化作用为主。相比之下,B段含有高岭石型的Ultisols-like古土壤和水成型的ineptisols -like古土壤,形成于强烈的风化条件下,以浸出作用(铁化作用)为主,并伴有泥化作用和水成作用。这一过程反映了从温带和半湿润的季节性降雨条件(a段)到温暖(温带)和湿润的多年性降雨条件(B段)的转变。这一垂直过程与白垩纪中期全球气候动力学相似,可能反映了Cenomanian-Turonian边界和OAE 2附近的变化,为完善南半球古气候重建提供了有价值的贡献。
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引用次数: 0
Seismogenic liquefaction with M ∼ 3.5 in fine-grained sediments: An experimental approach 细粒沉积物中M ~ 3.5的发震液化:实验方法
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-10 DOI: 10.1016/j.sedgeo.2025.106833
Szymon Świątek, Małgorzata Pisarska-Jamroży
Seismically liquefaction-induced soft-sediment deformation structures are key to understanding the geological history of earthquakes and sedimentary environments. These evidences usually have been associated with high-magnitude seismic events, above 5. However, the precise thresholds and mechanisms, especially for lower-magnitude earthquakes, remained unclear. This study aims to address this gap by experimentally investigating the development of deformation structures under controlled laboratory conditions. Using three sediment types arranged in five sequences, the sediments were subjected to low-magnitude seismic vibrations. Developed liquefaction features such as clastic volcanoes, pseudonodules, flame structures, and load casts were measured by a novel morphometric analysis to quantify their size and shape. The findings revealed that even at a magnitude of ∼3.5, liquefaction and deformation structures can occur, especially in high water-saturated fine-grained sediments. These results provide new insights into the thresholds of seismically-induced liquefaction and highlight the importance of considering lower-magnitude events in seismic risk assessments, offering significant implications for the study of sedimentary processes and earthquake-related deformation.
地震液化引起的软沉积变形构造是了解地震地质历史和沉积环境的关键。这些证据通常与5级以上的高震级地震事件有关。然而,精确的阈值和机制,特别是对于低震级的地震,仍然不清楚。本研究旨在通过实验研究变形结构在受控实验室条件下的发展来解决这一差距。利用分布在5个层序中的3种沉积物类型,对沉积物进行了低震级地震作用。发达的液化特征,如碎屑火山、假结节、火焰结构和负载铸件,通过一种新的形态计量学分析来量化它们的大小和形状。研究结果表明,即使在~ 3.5级,液化和变形结构也会发生,特别是在高水饱和的细粒沉积物中。这些结果为地震诱发液化的阈值提供了新的见解,并强调了在地震风险评估中考虑低震级事件的重要性,为沉积过程和地震相关变形的研究提供了重要意义。
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引用次数: 0
Re-inundation of the North China epeiric platform: A cyclic peritidal succession above a Lower–Middle Ordovician unconformity in southern Korea 华北陆表台地的再淹没:朝鲜南部下-中奥陶统不整合之上的旋回潮缘演替
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-03 DOI: 10.1016/j.sedgeo.2025.106824
Se Hyun Cho, Suk-Joo Choh
The depositional record of epeiric platforms is typically interrupted by unconformities, reflecting repetition of sedimentation and non-deposition. The Ordovician epeiric platform on the North China includes a Lower to Middle Ordovician unconformity, and this study documented early Darriwilian re-inundation events in the Makgol Formation from four sections over a distance of 25 km in the Taebaek area, eastern North China Craton.
The Makgol Formation mainly comprises micritic limestone with subordinate laminite and grainy facies, exhibiting subaerial exposure features in its lower part, and is interpreted as a micrite-dominated inner platform deposit. The re-inundation pattern is characterized by accumulation of metre-scale peritidal and subtidal cycles, which show an overall deepening upward trend, marked by a decrease in exposure features and an increase in subtidal cycles. However, this deepening trend was not gradual and occurred stepwise. Seven cycle sets, each consisting of one to six cycles, are described along with eight correlated key flooding surfaces. Each flooding event caused retreat of the facies belt to varying degrees, while cycles within cycle sets exhibited shallowing upward stacking patterns. These deepening upward trends are similar to punctuated transgressions observed in continental shelves, which suggest the applicability of the sequence stratigraphic concept from continental margins to inner epeiric platforms.
Lateral variations in the number of cycles between sections are recognised in seven intervals, four of which are interpreted as the result from erosion and non-deposition associated with subaerial exposure features. This finding suggests the incompleteness in transgressive deposits in inner epeiric platform conditions and highlights the importance of identifying missing cycles for the interpretation of stacking pattern and origin of metre-scale cycles.
表陆台地的沉积记录通常被不整合面打断,反映了沉积和非沉积的重复。华北地区奥陶系表台地包括下奥陶统至中奥陶统不整合,本研究在华北克拉通东部太白地区进行了四段25 km范围内的马戈里组早期Darriwilian再淹没事件的记录。Makgol组主要由泥晶灰岩组成,下部为次级纹层岩和颗粒相,下部具有陆上出露特征,为泥晶为主的内台地矿床。再淹没格局以米尺度潮周和潮下旋回的积累为特征,总体呈加深上升趋势,暴露特征减少,潮下旋回增加。然而,这种加深的趋势不是渐进的,而是逐步发生的。描述了七个循环集,每个循环集由一到六个循环组成,以及八个相关的关键淹水面。每次淹水事件均不同程度地导致相带退缩,旋回组内旋回呈现浅层向上叠加模式。这种不断加深的上升趋势与陆架上观察到的断续海侵相似,表明层序地层学概念从大陆边缘到内表台地的适用性。剖面之间旋回数量的横向变化在7个区间内被识别出来,其中4个被解释为与地面暴露特征相关的侵蚀和非沉积的结果。这一发现表明了内表陆台地条件下海侵沉积的不完全性,并强调了识别缺失旋回对于解释米尺度旋回的堆积模式和成因的重要性。
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引用次数: 0
Experiments study on landslide motion and damming deposit for particle and block materials with different mechanical properties 不同力学性能的颗粒和块状材料的滑坡运动与筑坝沉降试验研究
IF 2.7 2区 地球科学 Q1 GEOLOGY Pub Date : 2025-02-03 DOI: 10.1016/j.sedgeo.2025.106825
Ming-wei Ma , Jia-wen Zhou , Xing-guo Yang , Yi-hui Liang , Tao Yang , Hai-mei Liao
This study explores the impact of granular materials with varying moisture contents and particle sizes, as well as block materials with different volumes and layer strengths, on landslide fragmentation, motion, and deposit. The experimental results show that as particle size increases, the maximum dam height (Hmax) and width (Wmax) increase, while the minimum dam height (Hmin) decreases, indicating an improvement in the stability of landslide dams. Larger particle sizes are less sensitive to changes in moisture content. Additionally, moisture content inhibits Wmax, with mixed particle-size materials showing a greater reduction compared to single particle-size materials. As Wmax increases, the maximum dam length (Lmax) decreases exponentially. Sliding time (Ts), deposition time (Td), and total time (T) decrease as particle size increases. For mixed particle-size materials, a more continuous particle size distribution further reduces Ts, Td, and T. Block material experiments show that with increasing block volume, Wmax, Lmax, and Hmax increase significantly, with corresponding increases in Ts, Td, and T. When the strength of the lower layer material decreases, Wmax and Hmax decrease, while Ts, Td, and T increase. Conversely, when the lower layer material strength increases, the opposite effect is observed. Frictional energy loss (Ef) is the primary energy loss pathway, with both total energy loss and Ef decreasing with increasing particle size. Localized energy losses are mainly due to terrain collisions, independent of moisture content.
本研究探讨了不同含水率和粒径的粒状物质,以及不同体积和层强度的块体物质对滑坡破碎、运动和沉积的影响。试验结果表明,随着粒径的增大,最大坝高(Hmax)和坝宽(Wmax)增大,最小坝高(Hmin)减小,表明滑坡体坝的稳定性得到改善。较大的颗粒尺寸对水分含量的变化不太敏感。此外,水分含量抑制Wmax,与单一粒径材料相比,混合粒径材料显示出更大的减少。随着Wmax的增大,最大坝长Lmax呈指数递减。滑动时间(Ts)、沉积时间(Td)和总时间(T)随粒径的增大而减小。对于混合粒径材料,粒径分布更加连续,进一步降低了Ts、Td、T。砌块材料实验表明,随着砌块体积的增大,Wmax、Lmax、Hmax显著增大,Ts、Td、T也相应增大。下层材料强度降低,Wmax、Hmax减小,Ts、Td、T增大。相反,当下层材料强度增加时,观察到相反的效果。摩擦能量损失(Ef)是主要的能量损失途径,总能量损失和Ef都随着粒径的增大而减小。局部能量损失主要是由于地形碰撞造成的,与水分含量无关。
{"title":"Experiments study on landslide motion and damming deposit for particle and block materials with different mechanical properties","authors":"Ming-wei Ma ,&nbsp;Jia-wen Zhou ,&nbsp;Xing-guo Yang ,&nbsp;Yi-hui Liang ,&nbsp;Tao Yang ,&nbsp;Hai-mei Liao","doi":"10.1016/j.sedgeo.2025.106825","DOIUrl":"10.1016/j.sedgeo.2025.106825","url":null,"abstract":"<div><div>This study explores the impact of granular materials with varying moisture contents and particle sizes, as well as block materials with different volumes and layer strengths, on landslide fragmentation, motion, and deposit. The experimental results show that as particle size increases, the maximum dam height (<em>H</em><sub><em>max</em></sub>) and width (<em>W</em><sub><em>max</em></sub>) increase, while the minimum dam height (<em>H</em><sub><em>min</em></sub>) decreases, indicating an improvement in the stability of landslide dams. Larger particle sizes are less sensitive to changes in moisture content. Additionally, moisture content inhibits <em>W</em><sub><em>max</em></sub>, with mixed particle-size materials showing a greater reduction compared to single particle-size materials. As <em>W</em><sub><em>max</em></sub> increases, the maximum dam length (<em>L</em><sub><em>max</em></sub>) decreases exponentially. Sliding time (<em>T</em><sub><em>s</em></sub>), deposition time (<em>T</em><sub><em>d</em></sub>), and total time (<em>T</em>) decrease as particle size increases. For mixed particle-size materials, a more continuous particle size distribution further reduces <em>T</em><sub><em>s</em></sub>, <em>T</em><sub><em>d</em></sub>, and <em>T</em>. Block material experiments show that with increasing block volume, <em>W</em><sub><em>max</em></sub>, <em>L</em><sub><em>max</em></sub>, and <em>H</em><sub><em>max</em></sub> increase significantly, with corresponding increases in <em>T</em><sub><em>s</em></sub><em>, T</em><sub><em>d</em></sub>, and <em>T</em>. When the strength of the lower layer material decreases, <em>W</em><sub><em>max</em></sub> and <em>H</em><sub><em>max</em></sub> decrease, while <em>T</em><sub><em>s</em></sub><em>, T</em><sub><em>d</em></sub>, and <em>T</em> increase. Conversely, when the lower layer material strength increases, the opposite effect is observed. Frictional energy loss (<em>E</em><sub><em>f</em></sub>) is the primary energy loss pathway, with both total energy loss and <em>E</em><sub><em>f</em></sub> decreasing with increasing particle size. Localized energy losses are mainly due to terrain collisions, independent of moisture content.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"478 ","pages":"Article 106825"},"PeriodicalIF":2.7,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143336963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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Sedimentary Geology
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