Sedimentology最新文献

{"title":"Holocene seismic activity in south‐eastern Switzerland: Evidence from the sedimentary record of Lake Silvaplana","authors":"B. Bellwald, V. Nigg, S. Fabbri, L. Becker, A. Gilli, F. Anselmetti","doi":"10.1111/sed.13131","DOIUrl":"https://doi.org/10.1111/sed.13131","url":null,"abstract":"High‐Alpine regions are prone to a large variety of geohazards, among which earthquakes have the strongest impact on landscape and local population. Historic records indicate a moderate to high seismic activity in the northern, south‐western and central parts of Switzerland. In contrast, south‐eastern Switzerland has less historic earthquake chronicles due to the low population density, resulting in a poorly constrained seismic event catalogue. The aim of this study is to evaluate the palaeoseismic activity for south‐eastern Switzerland by using the sedimentary record of Lake Silvaplana in the Engadine Valley. A dense grid of high‐resolution two‐dimensional seismic profiles, high‐resolution bathymetry and a 10 m long sediment core from the deepest basin were used to investigate the stratigraphy of the lake sediments. The bathymetry reveals a flat basin, flanked by steep slopes to the north‐west and south‐east. The acoustic basement consists of four ridges, and gently‐dipping fans to the south‐west and north‐east. Expressions of slope failure can be identified in all domains of the lake floor and the subsurface data. Multiple coevally‐triggered chaotic mass‐flow deposits, overlain by megaturbidites with a coarse‐sand base, have been detected along ten horizons in the seismic data. The four most recent of these deposits are cored and radiocarbon dated to approximately 230, 310, 960 and 1330 cal yr BP, indicating four over‐regional seismic events that triggered large slope failures in Lake Silvaplana in the last 1400 years. Correlation with sediments of Lake Sils, Lake Como, Lake Iseo and Lake Ledro indicate within radiocarbon uncertainties a large earthquake around 1330 cal yr BP. Within their age ranges, the postulated earthquake at 310 cal yr BP (1640 CE) further correlates with a moment magnitude Mw ca 5.4 event in Ftan in 1622 CE, and the 960 cal yr BP (990 CE) earthquake correlates with a Mw ca 5.2 earthquake in Brescia in 1065 CE. Six mass‐movement deposits, also suggested to be caused by earthquakes, were not reached by the sediment core and have suggested ages between 7800 and 11300 cal yr BP. Thus, Lake Silvaplana sediments provide the first reliable record of seismic activity for the mid and Late Holocene in this region, likely related to the neotectonic activity of the Engadine Line, a major fault zone running along the main valley.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90061797","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}

{"title":"Spatial distribution and variability of lobe facies in a large sand‐rich submarine fan system: Neoproterozoic Zerrissene Group, Namibia","authors":"N. Nieminski, T. McHargue, J. Gooley, A. Fildani, D. Lowe","doi":"10.1111/sed.13129","DOIUrl":"https://doi.org/10.1111/sed.13129","url":null,"abstract":"The deposits of the upper Neoproterozoic Zerrissene Group of central‐western Namibia represent a large siliciclastic deep‐water depositional system that showcases the intricacies of facies and architectural relationships from bed‐scale to fan‐system‐scale. The lack of vegetation in the Namib Desert and regular east–west repetition of folded stratigraphy (reflecting ca 50% tectonic shortening) provides quasi‐three‐dimensional exposure over a current area of approximately 2700 square kilometres. The Brak River Formation, the middle sand‐rich unit of the Zerrissene Group, consists of nearly 600 m of strata exposed in multiple parallel continuous outcrops up to ca 10 km in length and oriented obliquely to depositional dip. Ten stratigraphic sections are correlated ca 32 km (ca 64 km restored) across the basin and offer exposure comparable in scale to modern submarine fans. Six sedimentary facies are identified and grouped into four facies associations that represent axial‐to‐marginal portions of deep‐water lobes in an unconfined submarine fan system. Spatial facies patterns, regional thickness variations, and palaeocurrents indicate that Brak River Formation sediments were transported primarily from the north to south–south‐west through a trough‐like basin and deposited within an unconfined basin plain at the junction of the Adamastor and Khomas oceans. The unique outcrop exposure and extent permits the documentation of system‐scale architecture and basin configuration of the Brak River submarine fan system. A transition from the sand‐rich lower Brak River Formation to more intercalated mudstone‐dominated intervals in the middle and upper Brak River Formation is interpreted to record a change from aggradational to compensational stacking of lobe deposits. This records the evolution of a large submarine fan as it filled the subtle seafloor topography and became less confined at the system‐scale. The documentation of these deep‐water deposits from centimetre‐scale to basin‐scale provides a new model for a system with extensive long‐distance transport of sand‐rich sediment gravity flows to submarine lobes without apparent channelization.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85747279","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}

{"title":"Geochemical evidence of provenance diversity in Holocene sandy land of Qinghai Lake Basin in north‐eastern margin of Qinghai–Tibet Plateau and its implications for climate change","authors":"Zhiyong Ding, Ruijie Lu, Xiaokang Liu, Yongqiu Wu, Dongxue Chen","doi":"10.1111/sed.13128","DOIUrl":"https://doi.org/10.1111/sed.13128","url":null,"abstract":"","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72838185","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}

{"title":"Sedimentological and ichnological characterization of delta front mouth bars in a river‐dominated delta (Upper Cretaceous) from the La Anita Formation, Austral Basin, Argentina","authors":"J. Ponce, N. Carmona, Damián Jait, Martín F. Cevallos, Christian Rojas","doi":"10.1111/sed.13127","DOIUrl":"https://doi.org/10.1111/sed.13127","url":null,"abstract":"","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87010558","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}

{"title":"Sedimentary evolution and sequence stratigraphy of Ediacaran high‐grade phosphorite–dolomite‐shale successions of Bocaina Formation (Corumbá Group), Central Brazil: Implications for the Neoproterozoic phosphogenic event","authors":"J. Hippertt, I. D. Rudnitzki, L. Morais, B. Freitas, G. R. Romero, H. A. Fernandes, M. G. P. Leite, J. Leme, P. Boggiani, R. Trindade","doi":"10.1111/sed.13125","DOIUrl":"https://doi.org/10.1111/sed.13125","url":null,"abstract":"Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis and the preservation of key Ediacaran biotas. However, high‐grade Ediacaran phosphorite deposits are relatively uncommon, diminishing the opportunity to test current phosphate mineralization–deposition models and their implications for Neoproterozoic research. In this scenario, widespread Ediacaran phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group – Central Brazil) are poorly explored in international literature. Nevertheless, recent advances in phosphate exploration gave access to continuous drill core sections and freshly opened mine pits, revealing an unprecedented record of complex phosphatic successions featuring the occurrence of Ediacaran microfossils assigned to the Doushantuo–Pertatataka assemblages. This work seeks to constrain main lithofacies, sequence stratigraphy and depositional settings from these phosphatic successions in order to analyse the sedimentary evolution of the unit under the current Neoproterozoic phosphorite research framework. These results indicate that the Bocaina Formation records secular sustained phosphate deposition. These deposits are related to unprecedented, microbialite reef rim phosphorites deposited during a lower accretionary rimmed platform stage, followed by the deposition of Doushantuo‐like, whole platform phosphorites associated with a later, drowned platform stage, therefore, reinforcing the evidence for the operation of strong allogeneic controls on phosphate mineralization–concentration. In addition, this study concludes that fossiliferous Ediacaran phosphatic deposits such as the Bocaina Formation are important to understanding Neoproterozoic phosphogenic events, because they may record the transition from a Precambrian to Phanerozoic‐like phosphogenesis associated with the instauration of the Ediacaran–Cambrian phosphatic taphonomic window. This evidence hints that the growing dataset from the Bocaina Formation may bring new, exciting perspectives for Neoproterozoic research as a whole.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74386207","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}

{"title":"Tracing the sedimentary response to the rifting and opening of the Meso‐Tethys Ocean","authors":"Jian‐Jun Fan, Bo‐Chuan Zhang, Y. Niu, An‐Bo Luo, Yu-jie Hao","doi":"10.1111/sed.13126","DOIUrl":"https://doi.org/10.1111/sed.13126","url":null,"abstract":"","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81669630","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}

{"title":"Effects of sodium and potassium concentrations on dolomite formation rate, stoichiometry and crystallographic characteristics","authors":"Mohammed S. Hashim, K. Rose, H. F. Cohen, Stephen E. Kaczmarek","doi":"10.1111/sed.13124","DOIUrl":"https://doi.org/10.1111/sed.13124","url":null,"abstract":"This study uses high temperature (215°C) dolomitization experiments to explore the effects of sodium (Na) and potassium (K), two common constituents of natural fluids, on dolomite formation rate, stoichiometry and crystallographic characteristics. In these experiments, aragonite ooids were dolomitized in Mg–Ca–Cl solutions with either no additional salt, or in solutions containing NaCl or KCl at different concentrations. Results show that Na solutions, and to a lesser extent K solutions, correlate with faster reaction rates and that Na at hypersaline fluid concentrations produces dolomites with higher stoichiometry, higher micro‐strain and lower cation ordering. Potassium has a different effect on the dolomite than Na at similar concentrations. Unlike Na, K does not cause micro‐strain but leads to dolomite with smaller unit cell parameters. It is proposed that Na and K catalyse dolomite precipitation and increase stoichiometry by weakening Mg hydration bonds which consequently facilitates Mg incorporation into dolomite. The decrease in dolomite cation ordering at higher Na concentrations may stem from the incorporation of Na into dolomite which strains the crystal lattice and reduces cation order. On the basis that high‐temperature experiments are applicable to natural dolomites, several implications pertinent to natural dolomites are drawn from the results. Firstly, the data suggest that the higher concentrations of Na and K in evaporative fluids (i.e. higher salinity) can explain why dolomite is generally more abundant and more stoichiometric in evaporative settings. Secondly, the results challenge a key prediction of the mixing zone dolomitization model by showing that higher Na and K concentrations increase, rather than decrease, both dolomitization rate and stoichiometry. Thirdly, the observed decrease in dolomite cation ordering with increasing Na and K concentrations implies that evaporative fluids would produce less stable dolomite that may be more prone to subsequent recrystallization and thus resetting of primary geochemical signatures.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74720287","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}

{"title":"A depositional model for meandering rivers without land plants","authors":"Michel Hasson, M. Marvin, Andrew W Gunn, A. Ielpi, M. Lapôtre","doi":"10.1111/sed.13121","DOIUrl":"https://doi.org/10.1111/sed.13121","url":null,"abstract":"The recognition of meandering rivers in Earth's prevegetation stratigraphic record is hindered by an absence of depositional models specifically tailored to unvegetated single‐channel rivers. As a result, their abundance on the early Earth is currently unknown. Here, sedimentological studies of two modern meandering river reaches with unvegetated banks were conducted. Both reaches are located in arid basins of Nevada, USA. Stratigraphy was analysed in conjunction with satellite imagery and high‐resolution topographic data to understand how channels and floodplains record past flow conditions. Analyses of point‐bar and channel‐fill deposits showed that lateral accretion sets are not heterolithic but, rather, composed of mixed sand and sand‐sized mud aggregates (clumps of clay and silt) interpreted to have formed through flocculation. Levées are present but subdued. Notably, downstream‐migrating outer‐bank‐attached bars are prominent architectural features that may be common in unvegetated meandering rivers in arid landscapes elsewhere. The identification of such depositional elements in the stratigraphic record may enhance recognition of ancient unvegetated meandering rivers and improve reconstructions of palaeohydrology on early Earth and Mars.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89828923","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}

{"title":"Pearl River sediment dispersal over its associated delta‐estuary‐shelf system during the Holocene","authors":"Yuanyuan Chen, B. Deng, Y. Saito, Zhanghua Wang, Xiaoqiang Yang, Jiaxue Wu","doi":"10.1111/sed.13123","DOIUrl":"https://doi.org/10.1111/sed.13123","url":null,"abstract":"To understand the Holocene sedimentary evolution of the Pearl River associated delta–estuary–shelf system, high‐resolution seismic data were acquired from Lingdingyang Bay to the inner shelf. A Pearl‐derived Holocene subaqueous clinoform developed over the pre‐Holocene incised channel/valley network. Overlying the Holocene ravinement surface, progradational highstand and acoustically semi‐transparent or transparent transgressive system tracts are separated by a maximum flooding surface. Restricted and thick in‐channel/in‐valley retrogressive deposits represent an earlier transgressive deposit. Displaying a westward‐oriented along‐shore extent, the highstand sediment accumulated asymmetrically within 30 m water depths, corresponding to a modern hydrodynamic environment. The wedge‐shaped highstand unit thickened landward with a depocentre (>15 m) located in western Lingdingyang Bay, possibly because of higher sediment trap efficiency inside the salinity front. Preliminary analyses suggest that the Pearl River has been trapping sediment to fill its extensive estuarine system for most of the Holocene and its sediment trap efficiency is greater since the sea‐level highstand. Since ca 7.5 ka bp, the total volume of highstand sediment accumulated in the entire delta‐estuary‐shelf dispersal system was approximately 128.36 × 109 m3. The calculated highstand riverine sediment flux was 16.01 to 16.50 Mt/yr. This value is equivalent to approximately one‐fifth of the flux that occurred prior to widespread dam construction and likely related to late‐Holocene intensified anthropogenic influence in South China. Since ca 7.5 ka bp, only ca 35% of the Pearl‐derived sediment has been dispersed to offshore shelf areas from the delta‐estuary system. With the dramatic decrease in river sediment discharge in recent decades, a larger fraction of Pearl‐derived sediment transported to the shelf might have been interrupted and changed.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88766566","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}

{"title":"Constraints on dolomite formation in a Late Palaeozoic saline alkaline lake deposit, Junggar Basin, north‐west China","authors":"Pei Guo, Huaguo Wen, M. Sánchez‐Román","doi":"10.1111/sed.13122","DOIUrl":"https://doi.org/10.1111/sed.13122","url":null,"abstract":"Alkaline lakes (pH > 9) are among the few modern sedimentary environments that are hydrochemically favourable for low‐temperature dolomite formation. While Mg‐clays and Mg‐evaporites also form more easily in alkaline environments, few studies have focused on how the kinetically inhibited dolomite wins the competition for Mg2+. Here, a basin‐wide survey of the distribution, paragenesis and stable C, O and Mg isotopes of main Mg‐rich minerals in the Late Palaeozoic saline alkaline lake deposit of the north‐west Junggar Basin, north‐west China, is conducted to study the influence of the formation and diagenesis of eitelite, northupite and Mg‐clays on dolomite formation. Large, isolated dolomite crystals (20 to 70 μm in diameter), show positive δ13C values (ranging from +1 to +7‰) and a restricted distribution in the mudstones of the lake‐transitional zone. These crystals have been interpreted as organogenic dolomite driven by methanogenesis via fermentation of organic substrates. The δ18O values of dolomitic mudstones (from −7.4 to +3.4‰), calcitic mudstones (from −15.1 to −3.3‰) and bedded Na‐carbonate evaporites (from +0.08 to +3.7‰), together with their Mg isotopic compositions, suggest that dolomite was not enriched in the most concentrated environments or during stages with most Mg sources, but in the organic‐rich deposits containing few other authigenic Mg‐rich minerals. Dolomite is at a competitive disadvantage for Mg2+ ions compared to Mg‐evaporite and Mg‐clay minerals due to its slow crystallization rates and the deficiency of micritic calcium carbonate precursors. However, it can nucleate and progressively grow into large crystals (>20 μm) if bacterial methanogenesis could effectively lower porewater pH (<8.5) and induce the dissolution of generated eitelite, northupite or Mg‐clays. These findings suggest that high salinity and/or high alkalinity are not always favourable conditions for dolomite formation and highlight the active role of pH fluctuations in inducing low‐temperature dolomite formation.","PeriodicalId":21838,"journal":{"name":"Sedimentology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88818882","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}