Timur Bulatov, Yakov Yermakov, Anna Kulikova, Bulat Gareev, Mikhail Spasennykh
Thin tuff beds of the Late Jurassic–Early Cretaceous Bazhenovo Formation are laterally widespread in the central part of the West Siberian Basin (ca 0.5 million km2). However, the source of the tuff beds remains unclear. The stratigraphy, geochemistry and geochronology of the tuff beds were investigated to reveal their magmatic origin and potential source region. Most of the tuff beds are recorded in member 4 and can be correlated through the Bazhenovo sequence. Thin-section petrography and X-ray diffraction indicate that the tuffs mostly comprise clay minerals and K-feldspars. Less common minerals are plagioclase, quartz and pyrite. The geochemical composition of the Bazhenovo tuff beds suggests a parental magma origin of andesite/basalt, which came from volcanic arc-related settings. Considering the results of geochemical studies along with LA-ICP-MS zircon U–Pb dating (141.3 ± 0.3/2.8 Ma), the palaeovolcanoes of the Caucasus region or south-east Mongolia–North-East China are one of the potential source regions of the tuffs. The record of these tuffs indicates the intensive volcanic eruption during the Volgian–Ryazanian, accompanied by a very low-sedimentation rate and preservation in a reducing environment. The tuff beds have broad implications as an isochronous marker horizon and constraints for the numerical age of the Jurassic–Cretaceous boundary in the Boreal Realm.
西西伯利亚盆地中部(约 50 万平方公里)横向分布着晚侏罗世-早白垩世巴热诺沃地层的薄凝灰岩床。然而,凝灰岩床的来源仍不清楚。我们对凝灰岩床的地层学、地球化学和地质年代进行了研究,以揭示其岩浆起源和潜在的来源地区。大部分凝灰岩床记录在第 4 组中,并可通过巴热诺沃序列进行关联。薄片岩石学和 X 射线衍射表明,凝灰岩主要由粘土矿物和 K 长石组成。较少见的矿物是斜长石、石英和黄铁矿。巴热诺沃凝灰岩床的地球化学成分表明,其母岩来源于安山岩/玄武岩,来自与火山弧有关的环境。考虑到地球化学研究结果和 LA-ICP-MS 锆石 U-Pb 测定(141.3 ± 0.3/2.8 Ma),高加索地区或蒙古东南部-中国东北部的古火山是凝灰岩的潜在来源地区之一。这些凝灰岩的记录表明,在伏尔加-里亚期火山喷发密集,伴随着极低的沉积率,并保存在还原环境中。这些凝灰岩床作为等时标志层具有广泛的意义,并对北半球侏罗纪-白垩纪边界的数值年龄具有制约作用。
{"title":"Provenance and the U–Pb age constraints on the tuff beds of the Late Jurassic–Early Cretaceous Bazhenovo Formation, West Siberian Basin","authors":"Timur Bulatov, Yakov Yermakov, Anna Kulikova, Bulat Gareev, Mikhail Spasennykh","doi":"10.1002/dep2.281","DOIUrl":"10.1002/dep2.281","url":null,"abstract":"<p>Thin tuff beds of the Late Jurassic–Early Cretaceous Bazhenovo Formation are laterally widespread in the central part of the West Siberian Basin (<i>ca</i> 0.5 million km<sup>2</sup>). However, the source of the tuff beds remains unclear. The stratigraphy, geochemistry and geochronology of the tuff beds were investigated to reveal their magmatic origin and potential source region. Most of the tuff beds are recorded in member 4 and can be correlated through the Bazhenovo sequence. Thin-section petrography and X-ray diffraction indicate that the tuffs mostly comprise clay minerals and K-feldspars. Less common minerals are plagioclase, quartz and pyrite. The geochemical composition of the Bazhenovo tuff beds suggests a parental magma origin of andesite/basalt, which came from volcanic arc-related settings. Considering the results of geochemical studies along with LA-ICP-MS zircon U–Pb dating (141.3 ± 0.3/2.8 Ma), the palaeovolcanoes of the Caucasus region or south-east Mongolia–North-East China are one of the potential source regions of the tuffs. The record of these tuffs indicates the intensive volcanic eruption during the Volgian–Ryazanian, accompanied by a very low-sedimentation rate and preservation in a reducing environment. The tuff beds have broad implications as an isochronous marker horizon and constraints for the numerical age of the Jurassic–Cretaceous boundary in the Boreal Realm.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 2","pages":"312-334"},"PeriodicalIF":2.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140723109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rachid Ouchaou, Jean-Yves Reynaud, Youn Besse, Anissa Tilehghouatine, Eric Armynot du Châtelet, Alain Trentesaux, Romain Abraham, Laurent Deschodt, Guillaume Hulin, Samuel Desoutter, Benjamin Fores, François-Xavier Simon, Mathieu Lançon
The French Flemish Coastal Plain, which extends from Denmark to France, is characterised by a topography close to sea level and protected by a system of coastal dunes. Quaternary sediments, comprised of marine, estuarine and continental deposits, accumulated by infilling and then prograding above a network of incised valleys. This study focusses on the Holocene infill of the Denna palaeoestuary, south-west to Dunkerque. Surface geophysics (electrical conductivity and ground-penetrating radar) and vibrocore data are used to reconstruct the landscape evolution during the last stages of sedimentation. The conductivity map highlights the last network of tidal channels, ditches and dikes of the eastern side of the palaeoestuary. Over the upper 4 m of the infill, the ground-penetrating radar profiles show two superimposed units. The bottom unit is composed of meandering channel bars and the top unit of flat strata intersected by sparse channels, mostly infilled in place. The sediment analysis of the vibrocores shows a predominantly sandy filling of marine to estuarine origin, evidenced by sponge spicules and a fauna of bivalves and foraminifera adapted to brackish settings. The uppermost deposit exhibits an oxidation profile which marks the groundwater zone transition. Clayey sediments are also present, infilling the uppermost channels and ditches dug during reclamation, in increasing proportions towards the axis of the estuarine palaeovalley. The tidal signature of sedimentary dynamics is evidenced by heterolithic facies in some channel fills and tidal rhythmites infilling scour depressions linked to dike breaching. The abrupt decrease in channel dynamics across the unit boundary, although sedimentation remained sandy in the upper unit, coincides with the development of embankment of the estuarine border and is tentatively interpreted as a result of reclamation.
{"title":"The depositional record of the French Flemish Coastal plain since antiquity: Impacts of land reclamation in a tide-dominated estuary","authors":"Rachid Ouchaou, Jean-Yves Reynaud, Youn Besse, Anissa Tilehghouatine, Eric Armynot du Châtelet, Alain Trentesaux, Romain Abraham, Laurent Deschodt, Guillaume Hulin, Samuel Desoutter, Benjamin Fores, François-Xavier Simon, Mathieu Lançon","doi":"10.1002/dep2.279","DOIUrl":"10.1002/dep2.279","url":null,"abstract":"<p>The French Flemish Coastal Plain, which extends from Denmark to France, is characterised by a topography close to sea level and protected by a system of coastal dunes. Quaternary sediments, comprised of marine, estuarine and continental deposits, accumulated by infilling and then prograding above a network of incised valleys. This study focusses on the Holocene infill of the Denna palaeoestuary, south-west to Dunkerque. Surface geophysics (electrical conductivity and ground-penetrating radar) and vibrocore data are used to reconstruct the landscape evolution during the last stages of sedimentation. The conductivity map highlights the last network of tidal channels, ditches and dikes of the eastern side of the palaeoestuary. Over the upper 4 m of the infill, the ground-penetrating radar profiles show two superimposed units. The bottom unit is composed of meandering channel bars and the top unit of flat strata intersected by sparse channels, mostly infilled in place. The sediment analysis of the vibrocores shows a predominantly sandy filling of marine to estuarine origin, evidenced by sponge spicules and a fauna of bivalves and foraminifera adapted to brackish settings. The uppermost deposit exhibits an oxidation profile which marks the groundwater zone transition. Clayey sediments are also present, infilling the uppermost channels and ditches dug during reclamation, in increasing proportions towards the axis of the estuarine palaeovalley. The tidal signature of sedimentary dynamics is evidenced by heterolithic facies in some channel fills and tidal rhythmites infilling scour depressions linked to dike breaching. The abrupt decrease in channel dynamics across the unit boundary, although sedimentation remained sandy in the upper unit, coincides with the development of embankment of the estuarine border and is tentatively interpreted as a result of reclamation.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 5","pages":"685-707"},"PeriodicalIF":1.9,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.279","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jasper Maars, Gijs van Dijk, Mark J. Dekkers, F. Javier Hernández-Molina, Federico Andreetto, Francisco J. Rodríguez-Tovar, Wout Krijgsman
Palaeocurrent analysis is vital for basin analysis and helps in the interpretation of depositional environments (along-slope or downslope). For that, it is crucial to have multiple measuring methods at hand to apply palaeocurrent analysis with a wide range of different datasets (outcrops, cores and photographs). Here, two relatively underexploited palaeocurrent measurement techniques are assessed when applied to trough cross-stratification observed in the Arenazzolo Formation at Eraclea Minoa (Sicily). The first technique is a novel design of a qualitative approach to infer palaeocurrent directions from photographs of two-dimensional sedimentary structures. The second technique involves measurements of the anisotropy of magnetic susceptibility from drilled samples. A broad agreement, with overlapping uncertainty boundaries, is observed between results from both techniques. This agreement validates the use of trough cross-strata to infer palaeocurrent directions. Moreover, the addition of photographs improves reproducibility and prevents a bias towards the best-exposed troughs. The application of both techniques to outcrops and sedimentary cores provides new opportunities for palaeocurrent analysis in any type of sedimentary environment.
{"title":"New palaeocurrent analysis approach from two-dimensional trough cross-strata using photographs and anisotropy of magnetic susceptibility","authors":"Jasper Maars, Gijs van Dijk, Mark J. Dekkers, F. Javier Hernández-Molina, Federico Andreetto, Francisco J. Rodríguez-Tovar, Wout Krijgsman","doi":"10.1002/dep2.277","DOIUrl":"10.1002/dep2.277","url":null,"abstract":"<p>Palaeocurrent analysis is vital for basin analysis and helps in the interpretation of depositional environments (along-slope or downslope). For that, it is crucial to have multiple measuring methods at hand to apply palaeocurrent analysis with a wide range of different datasets (outcrops, cores and photographs). Here, two relatively underexploited palaeocurrent measurement techniques are assessed when applied to trough cross-stratification observed in the Arenazzolo Formation at Eraclea Minoa (Sicily). The first technique is a novel design of a qualitative approach to infer palaeocurrent directions from photographs of two-dimensional sedimentary structures. The second technique involves measurements of the anisotropy of magnetic susceptibility from drilled samples. A broad agreement, with overlapping uncertainty boundaries, is observed between results from both techniques. This agreement validates the use of trough cross-strata to infer palaeocurrent directions. Moreover, the addition of photographs improves reproducibility and prevents a bias towards the best-exposed troughs. The application of both techniques to outcrops and sedimentary cores provides new opportunities for palaeocurrent analysis in any type of sedimentary environment.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 2","pages":"298-311"},"PeriodicalIF":2.4,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.277","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140214292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper explores the response to Holocene ash inundation in different sub-environments of two fluvio-lacustrine systems, Las Piedritas and Totoral, focussing on the processes of volcaniclastic remobilisation. Sediment cores and outcrops were used to recognise three deposit types, noting how some differ from lahars, through sedimentological and stratigraphic analysis: (1) thick, laterally discontinuous, pumice-dominated deposits occur overlying alluvial plain and lower terrace surfaces across both watersheds; (2) chaotic, extremely poorly sorted and matrix-supported beds composed of both epiclastic and pyroclastic material occur as two conspicuous deposits at Las Piedritas outcrops, in a low-gradient confined channel setting; and (3) layers with an exclusively pyroclastic composition and no flow sedimentary structures or fragment roundness were found draping each of the two chaotic intervals and intercalating with the background sediment in Las Piedritas prodelta. Thick pumice packages capping the floodplains resulted from the overflow of streams carrying a floating pumice load. Due to its positive buoyancy, the pumice is transported as a slowly moving overlying mantle without mixing with the streamflow. The disorganised pattern and poor sorting of the matrix-rich polymictic beds are consistent with laminar, gravity-driven, high-concentration flows. They constitute secondary lahars, originating upstream from large run-off processes that reworked a pyroclastic substrate. The lack of reworking features in the vitric-rich units identified in the lake core retrieved from Las Piedritas prodelta, as well as the continuous and widespread occurrences of those interbedded in upstream outcrops, indicate an airfall origin. No reworked tephra unit is recognised in the prodelta sediment record, although various deposits from the hydrologic remobilisation of airfall tephra are found along the subaerial portion of both watersheds. Apparently, large amounts of flotation-remobilised tephra were retained on the delta plain, while another considerable fraction would have been carried away from the creek mouth under the influence of dominant regional winds.
本文探讨了 Las Piedritas 和 Totoral 这两个河流-湖沼系统的不同子环境对全新世火山灰淹没的反应,重点是火山碎屑的再移动过程。通过沉积学和地层学分析,利用沉积物岩心和露头确认了三种沉积类型,并注意到其中一些类型与火山岩的不同之处:(1) 厚的、横向不连续的、以浮石为主的沉积层出现在两个流域的冲积平原和下阶地表面上;(2) 杂乱的、分选极差的、基质支撑的床层,由外积岩和火成岩物质组成,是拉斯皮德里塔斯露头的两种明显的沉积层,出现在低梯度的封闭河道环境中;(3) 在 Las Piedritas prodelta 的两个混沌区间均发现了完全由火成岩组成的地层,没有流动沉积结构或圆形碎屑。洪泛平原上覆盖的厚厚浮石包是由携带浮石负荷的溪流溢出造成的。由于浮石具有正浮力,浮石作为缓慢移动的上覆地幔被搬运,不会与溪流混合。富含基质的多岩床形态杂乱,分选能力差,这与层流、重力驱动的高浓度流一致。它们是次级拉哈尔,源自上游对火成岩基质进行再加工的大型径流过程。从 Las Piedritas prodelta 取回的湖芯中发现的富含矾土的单位中缺乏再加工特征,而这些单位在上游露头地层中连续而广泛地存在,这表明它们起源于空气瀑布。虽然在两个流域的地下部分都发现了气流沉积物在水文作用下重新移动形成的各种沉积物,但在原岩沉积物记录中没有发现再加工的凝灰岩单元。显然,大量经浮选重新移动的凝灰岩被保留在三角洲平原上,而另有相当一部分则在区域主导风的影响下被带离溪口。
{"title":"Hydrologic remobilisation of tephra-fall deposits: A sedimentological analysis throughout fluvio-lacustrine systems of North-West Patagonia","authors":"Nahuel Losano, Gustavo Villarosa, Débora Beigt, Pablo Amat, Julieta Cottet, Valeria Outes","doi":"10.1002/dep2.274","DOIUrl":"10.1002/dep2.274","url":null,"abstract":"<p>This paper explores the response to Holocene ash inundation in different sub-environments of two fluvio-lacustrine systems, Las Piedritas and Totoral, focussing on the processes of volcaniclastic remobilisation. Sediment cores and outcrops were used to recognise three deposit types, noting how some differ from lahars, through sedimentological and stratigraphic analysis: (1) thick, laterally discontinuous, pumice-dominated deposits occur overlying alluvial plain and lower terrace surfaces across both watersheds; (2) chaotic, extremely poorly sorted and matrix-supported beds composed of both epiclastic and pyroclastic material occur as two conspicuous deposits at Las Piedritas outcrops, in a low-gradient confined channel setting; and (3) layers with an exclusively pyroclastic composition and no flow sedimentary structures or fragment roundness were found draping each of the two chaotic intervals and intercalating with the background sediment in Las Piedritas prodelta. Thick pumice packages capping the floodplains resulted from the overflow of streams carrying a floating pumice load. Due to its positive buoyancy, the pumice is transported as a slowly moving overlying mantle without mixing with the streamflow. The disorganised pattern and poor sorting of the matrix-rich polymictic beds are consistent with laminar, gravity-driven, high-concentration flows. They constitute secondary lahars, originating upstream from large run-off processes that reworked a pyroclastic substrate. The lack of reworking features in the vitric-rich units identified in the lake core retrieved from Las Piedritas prodelta, as well as the continuous and widespread occurrences of those interbedded in upstream outcrops, indicate an airfall origin. No reworked tephra unit is recognised in the prodelta sediment record, although various deposits from the hydrologic remobilisation of airfall tephra are found along the subaerial portion of both watersheds. Apparently, large amounts of flotation-remobilised tephra were retained on the delta plain, while another considerable fraction would have been carried away from the creek mouth under the influence of dominant regional winds.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 5","pages":"670-684"},"PeriodicalIF":1.9,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.274","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140237576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A tufa mound developed at La Saline Lake, an oxbow of the Athabasca River in the Athabasca Oil Sands deposit of north-east Alberta, is characterised by an unusual emplacement of a gypsum caprock. This two-tiered architecture resulted from the bicarbonate-saturated groundwater flow along Upper Devonian limestone being redirected deeper and encountering the halite–anhydrite dissolution trend within the underlying Middle Devonian Prairie Evaporite Formation, 175 to 200 m below. Migrations up-section of sulphate-saturated brine resulted in the gypsum caprock on the tufa mound and discharge of a sulphate-saturated brine spring with total dissolved solids of ca 80,000 mg/L. The brine spring is bifurcated with flows to the south-west and north-west. Calcite–gypsum thrombolytic bottom sediments along the south-western branch were covered by a halite deposit and subsequently a gypsum crust with a microbial community dominated by the cyanobacteria Coleofasciculus chthonoplastes. The thrombolite contact zone with the halite–gypsum encrustation has a more diversified community with the cyanobacteria Dactylococcopsis. Cyanobacterial mats that wrap around the bulbous gypsum crust protuberances distributed along the brine pool bottom surfaces have significant eukaryotic diversity, represented by the heterotrophic Ochrophyte Paraphysomonas. In contrast, sediments accumulated along the adjacent spring branch flow to the north-west were thicker and clogged by abundant decomposed and fermented floral debris, unlike the deposit accumulated along the south-western branch. This resulted in an oxygen-depleted anaerobic environment dominated by sulphate-reducing bacteria resulting in a calcite-rich and sulphate-starved anaerobic sediment with ca 20% elemental sulphur and emanation of H2S gas.
{"title":"Geochemical and microbiological variability of aerobic and anaerobic sediments along a bifurcated sulphate-saturated brine spring in western Canada","authors":"Paul L. Broughton","doi":"10.1002/dep2.276","DOIUrl":"10.1002/dep2.276","url":null,"abstract":"<p>A tufa mound developed at La Saline Lake, an oxbow of the Athabasca River in the Athabasca Oil Sands deposit of north-east Alberta, is characterised by an unusual emplacement of a gypsum caprock. This two-tiered architecture resulted from the bicarbonate-saturated groundwater flow along Upper Devonian limestone being redirected deeper and encountering the halite–anhydrite dissolution trend within the underlying Middle Devonian Prairie Evaporite Formation, 175 to 200 m below. Migrations up-section of sulphate-saturated brine resulted in the gypsum caprock on the tufa mound and discharge of a sulphate-saturated brine spring with total dissolved solids of <i>ca</i> 80,000 mg/L. The brine spring is bifurcated with flows to the south-west and north-west. Calcite–gypsum thrombolytic bottom sediments along the south-western branch were covered by a halite deposit and subsequently a gypsum crust with a microbial community dominated by the cyanobacteria <i>Coleofasciculus chthonoplastes</i>. The thrombolite contact zone with the halite–gypsum encrustation has a more diversified community with the cyanobacteria <i>Dactylococcopsis</i>. Cyanobacterial mats that wrap around the bulbous gypsum crust protuberances distributed along the brine pool bottom surfaces have significant eukaryotic diversity, represented by the heterotrophic Ochrophyte <i>Paraphysomonas</i>. In contrast, sediments accumulated along the adjacent spring branch flow to the north-west were thicker and clogged by abundant decomposed and fermented floral debris, unlike the deposit accumulated along the south-western branch. This resulted in an oxygen-depleted anaerobic environment dominated by sulphate-reducing bacteria resulting in a calcite-rich and sulphate-starved anaerobic sediment with <i>ca</i> 20% elemental sulphur and emanation of H<sub>2</sub>S gas.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 5","pages":"637-669"},"PeriodicalIF":1.9,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.276","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140265323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikhil Sharma, Alexander C. Whittaker, Thierry Adatte, Sébastien Castelltort
Water discharge and sediment flux variations are important parameters controlling the morphodynamic behaviour of rivers. Although quantitative estimates for water discharge and sediment flux variability are well-constrained for modern rivers, far fewer assessments of flow and sediment flux intermittency in ancient fluvial systems from the rock record are available. In this study, a relationship between water discharge, sediment flux variability and patterns of changing fluvial stratigraphic architecture in the Middle Eocene Escanilla Formation, Spain, is explored. Water discharge intermittency factor (IWF), calculated as a ratio of the total water discharge (over the averaging time period) to the instantaneous channel-forming water discharge if sustained for the same period, ranges from 0.03 to 0.11 in the high amalgamation intervals and from 0.10 to 0.32 in the low amalgamation intervals. Similarly, the sediment flux intermittency factor (ISF) is estimated to be in the range of 0.008 to 0.01 in the high amalgamation intervals and of 0.01 to 0.03 in the low amalgamation intervals. Consequently, high amalgamation intervals were most probably deposited under more intermittent and short-lived intense precipitation events while low amalgamation intervals were the result of less intermittent flows spread throughout the year. Overall, these estimates are consistent with values from modern ephemeral rivers typically found in arid to semi-arid climate and is in agreement with available proxy data for the Middle Eocene climatic context of the studied alluvial system. This highlights an important connection between hydroclimate, river morphodynamics and landscape evolution, and has implications to predict river flow and sediment transport across the Earth's surface in the geological past.
{"title":"Water discharge and sediment flux intermittency in the fluvial Escanilla Formation, Spain: Implications for changes in stratigraphic architecture","authors":"Nikhil Sharma, Alexander C. Whittaker, Thierry Adatte, Sébastien Castelltort","doi":"10.1002/dep2.272","DOIUrl":"https://doi.org/10.1002/dep2.272","url":null,"abstract":"<p>Water discharge and sediment flux variations are important parameters controlling the morphodynamic behaviour of rivers. Although quantitative estimates for water discharge and sediment flux variability are well-constrained for modern rivers, far fewer assessments of flow and sediment flux intermittency in ancient fluvial systems from the rock record are available. In this study, a relationship between water discharge, sediment flux variability and patterns of changing fluvial stratigraphic architecture in the Middle Eocene Escanilla Formation, Spain, is explored. Water discharge intermittency factor (I<sub>WF</sub>), calculated as a ratio of the total water discharge (over the averaging time period) to the instantaneous channel-forming water discharge if sustained for the same period, ranges from 0.03 to 0.11 in the high amalgamation intervals and from 0.10 to 0.32 in the low amalgamation intervals. Similarly, the sediment flux intermittency factor (I<sub>SF</sub>) is estimated to be in the range of 0.008 to 0.01 in the high amalgamation intervals and of 0.01 to 0.03 in the low amalgamation intervals. Consequently, high amalgamation intervals were most probably deposited under more intermittent and short-lived intense precipitation events while low amalgamation intervals were the result of less intermittent flows spread throughout the year. Overall, these estimates are consistent with values from modern ephemeral rivers typically found in arid to semi-arid climate and is in agreement with available proxy data for the Middle Eocene climatic context of the studied alluvial system. This highlights an important connection between hydroclimate, river morphodynamics and landscape evolution, and has implications to predict river flow and sediment transport across the Earth's surface in the geological past.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"245-259"},"PeriodicalIF":2.4,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.272","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139976552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Midcontinent Rift System of North America is one of the oldest continental rifts but rifting ceased before continental breakup. The southern segment of the Midcontinent Rift System lies in Kansas, USA, where the stratigraphic succession and rift evolution are largely unknown. This study analysed the rift basin infill in this part of the Midcontinent Rift System to propose a depositional model. The Precambrian rift succession was described in discontinuous cores drilled in the Texaco Noel Poersch#1 well in Washington County. Sixteen lithofacies were identified and grouped into four different facies associations (fluvial, aeolian, lacustrine and alluvial fan). Overall, the studied succession comprises continental deposits accumulated dominantly in alluvial and aeolian settings, with the intermittent development of lacustrine systems. The proposed depositional models for the available core intervals indicate cyclic patterns of overfilled and underfilled phases within the rift basin. These changes in the accommodation-to-supply ratio were controlled by tectonism and probably modulated by climate during evolution in the syn-rift phase. This study advances our understanding of variations across the Midcontinent Rift System.
{"title":"Facies analysis and depositional model of the Midcontinent Rift System in Kansas, USA","authors":"Iffat Azmi, Karin Goldberg","doi":"10.1002/dep2.275","DOIUrl":"10.1002/dep2.275","url":null,"abstract":"<p>The Midcontinent Rift System of North America is one of the oldest continental rifts but rifting ceased before continental breakup. The southern segment of the Midcontinent Rift System lies in Kansas, USA, where the stratigraphic succession and rift evolution are largely unknown. This study analysed the rift basin infill in this part of the Midcontinent Rift System to propose a depositional model. The Precambrian rift succession was described in discontinuous cores drilled in the Texaco Noel Poersch#1 well in Washington County. Sixteen lithofacies were identified and grouped into four different facies associations (fluvial, aeolian, lacustrine and alluvial fan). Overall, the studied succession comprises continental deposits accumulated dominantly in alluvial and aeolian settings, with the intermittent development of lacustrine systems. The proposed depositional models for the available core intervals indicate cyclic patterns of overfilled and underfilled phases within the rift basin. These changes in the accommodation-to-supply ratio were controlled by tectonism and probably modulated by climate during evolution in the syn-rift phase. This study advances our understanding of variations across the Midcontinent Rift System.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 2","pages":"282-297"},"PeriodicalIF":2.4,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.275","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140441171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo-Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X-ray diffraction reveal three distinct lithologies of bedded gypsum: bottom-growth gypsum, laminated gypsum and clastic gypsum. Bottom-growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian-reworked bottom-growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.
在与二叠三叠纪泛大陆红层硅质岩有关的层状蒸发岩中,层状石膏比较常见。然而,人们很少关注古石膏的纹理,而这些纹理可用于完善对沉积环境和成岩历史的解释。该项目描述了怀俄明州格雷布尔附近三叠纪红峰地层(楚格沃特组)露头的层状石膏的纹理。实地考察、岩相学和 X 射线衍射揭示了层状石膏的三种不同岩性:底部生长石膏、层状石膏和碎屑石膏。底生石膏沉淀在浅盐地表水体的底部。层状石膏可能形成于浅盐湖和泥滩。碎屑石膏单元由沉积于沙滩的底部生长石膏晶体经风化再加工而成。红色硅质泥岩的特点是块状和大量块状碎屑。对这一赤峰地层露头的详细研究表明,该地层形成于浅盐湖及相关的泥滩、沙滩和沙漠土壤中。
{"title":"Gypsum lakes, sandflats and soils revealed from the Triassic Red Peak Formation of the Chugwater Group, north-central Wyoming","authors":"Maya Yamei Bradford, Kathleen C. Benison","doi":"10.1002/dep2.273","DOIUrl":"10.1002/dep2.273","url":null,"abstract":"<p>Bedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo-Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X-ray diffraction reveal three distinct lithologies of bedded gypsum: bottom-growth gypsum, laminated gypsum and clastic gypsum. Bottom-growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian-reworked bottom-growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"260-278"},"PeriodicalIF":2.4,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139790511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cinthya Nava-Fernandez, Tobias Braun, Chelsea L. Pederson, Bethany Fox, Adam Hartland, Ola Kwiecien, Sebastian N. Höpker, Stefano Bernasconi, Madalina Jaggi, John Hellstrom, Fernando Gázquez, Amanda French, Norbert Marwan, Adrian Immenhauser, Sebastian F. M. Breitenbach
El Niño–Southern Oscillation dynamics affect global weather patterns, with regionally diverse hydrological responses posing critical societal challenges. The lack of seasonally resolved hydrological proxy reconstructions beyond the observational era limits our understanding of boundary conditions that drive and/or adjust El Niño–Southern Oscillation variability. Detailed reconstructions of past El Niño–Southern Oscillation dynamics can help modelling efforts, highlight impacts on disparate ecosystems and link to extreme events that affect populations from the tropics to high latitudes. Here, mid-Holocene El Niño–Southern Oscillation and hydrological changes are reconstructed in the south-west Pacific using a stalagmite from Niue Island, which represents the period 6.4–5.4 ka BP. Stable oxygen and carbon isotope ratios, trace elements and greyscale data from a U/Th-dated and layer counted stalagmite profile are combined to infer changes in local hydrology at sub-annual to multi-decadal timescales. Principal component analysis reveals seasonal-scale hydrological changes expressed as variations in stalagmite growth patterns and geochemical characteristics. Higher levels of host rock-derived elements (Sr/Ca and U/Ca) and higher δ18O and δ13C values are observed in dark, dense calcite laminae deposited during the dry season, whereas during the wet season, higher concentrations of soil-derived elements (Zn/Ca and Mn/Ca) and lower δ18O and δ13C values are recorded in pale, porous calcite laminae. The multi-proxy record from Niue shows seasonal cycles associated with hydrological changes controlled by the positioning and strength of the South Pacific Convergence Zone. Wavelet analysis of the greyscale record reveals that El Niño–Southern Oscillation was continuously active during the mid-Holocene, with two weaker intervals at 6–5.9 and 5.6–5.5 ka BP. El Niño–Southern Oscillation especially affects dry season rainfall dynamics, with increased cyclone activity that reduces hydrological seasonality during El Niño years.
厄尔尼诺-南方涛动的动态影响着全球天气模式,各地区不同的水文反应给社会带来了严峻的挑战。由于缺乏观测时代以外的季节分辨水文代用指标重建,限制了我们对驱动和/或调整厄尔尼诺-南方涛动变异的边界条件的理解。对过去厄尔尼诺-南方涛动动态的详细重建有助于建模工作,突出对不同生态系统的影响,并与影响从热带到高纬度人口的极端事件联系起来。本文利用纽埃岛的石笋重建了全新世中期厄尔尼诺-南方涛动和西南太平洋的水文变化,该石笋代表了 6.4-5.4 ka BP 时期。将稳定的氧和碳同位素比值、微量元素和来自 U/Th 日期和层计数石笋剖面的灰度数据结合起来,推断出当地水文在次年至数十年时间尺度上的变化。主成分分析表明,季节尺度的水文变化表现为石笋生长模式和地球化学特征的变化。在旱季沉积的深色致密方解石层中,可以观察到较高水平的主岩衍生元素(Sr/Ca 和 U/Ca)和较高的 δ18O 和 δ13C 值;而在雨季,在浅色多孔方解石层中,可以记录到较高浓度的土壤衍生元素(Zn/Ca 和 Mn/Ca)和较低的 δ18O 和 δ13C 值。纽埃的多代理记录显示了与南太平洋辐合带的位置和强度所控制的水文变化有关的季节性周期。对灰度记录的小波分析表明,厄尔尼诺-南方涛动在全新世中期持续活跃,在 6-5.9 ka BP 和 5.6-5.5 ka BP 有两个较弱的时期。厄尔尼诺-南方涛动尤其影响旱季降雨动态,在厄尔尼诺年,气旋活动增加,降低了水文季节性。
{"title":"Mid-Holocene rainfall seasonality and ENSO dynamics over the south-western Pacific","authors":"Cinthya Nava-Fernandez, Tobias Braun, Chelsea L. Pederson, Bethany Fox, Adam Hartland, Ola Kwiecien, Sebastian N. Höpker, Stefano Bernasconi, Madalina Jaggi, John Hellstrom, Fernando Gázquez, Amanda French, Norbert Marwan, Adrian Immenhauser, Sebastian F. M. Breitenbach","doi":"10.1002/dep2.268","DOIUrl":"10.1002/dep2.268","url":null,"abstract":"<p>El Niño–Southern Oscillation dynamics affect global weather patterns, with regionally diverse hydrological responses posing critical societal challenges. The lack of seasonally resolved hydrological proxy reconstructions beyond the observational era limits our understanding of boundary conditions that drive and/or adjust El Niño–Southern Oscillation variability. Detailed reconstructions of past El Niño–Southern Oscillation dynamics can help modelling efforts, highlight impacts on disparate ecosystems and link to extreme events that affect populations from the tropics to high latitudes. Here, mid-Holocene El Niño–Southern Oscillation and hydrological changes are reconstructed in the south-west Pacific using a stalagmite from Niue Island, which represents the period 6.4–5.4 ka BP. Stable oxygen and carbon isotope ratios, trace elements and greyscale data from a U/Th-dated and layer counted stalagmite profile are combined to infer changes in local hydrology at sub-annual to multi-decadal timescales. Principal component analysis reveals seasonal-scale hydrological changes expressed as variations in stalagmite growth patterns and geochemical characteristics. Higher levels of host rock-derived elements (Sr/Ca and U/Ca) and higher δ<sup>18</sup>O and δ<sup>13</sup>C values are observed in dark, dense calcite laminae deposited during the dry season, whereas during the wet season, higher concentrations of soil-derived elements (Zn/Ca and Mn/Ca) and lower δ<sup>18</sup>O and δ<sup>13</sup>C values are recorded in pale, porous calcite laminae. The multi-proxy record from Niue shows seasonal cycles associated with hydrological changes controlled by the positioning and strength of the South Pacific Convergence Zone. Wavelet analysis of the greyscale record reveals that El Niño–Southern Oscillation was continuously active during the mid-Holocene, with two weaker intervals at 6–5.9 and 5.6–5.5 ka BP. El Niño–Southern Oscillation especially affects dry season rainfall dynamics, with increased cyclone activity that reduces hydrological seasonality during El Niño years.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"176-194"},"PeriodicalIF":2.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.268","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139683596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marianna I. Tuchkova, Elena V. Vatrushkina, Sergey D. Sokolov
In the Mesozoic succession of the Anyui–Chukotka fold system (North-East Russia), five stratigraphic intervals were recognised that have an abundance of gravity flow deposits. These are the Olenekian (Lower Triassic), Upper Carnian, Upper Norian, Oxfordian–Kimmeridgian and Valanginian. The Triassic gravity flow deposits formed on the south-facing, passive margin of the Chukotka microplate and consist of greywackes and lithic arenites. Palaeocurrent data indicate that the flows were directed towards the south-east. The Olenekian gravity flow units consist of clast-rich sandstone deposited on the continental slope, and clast-poor sandstone deposited at the base of the slope. Upper Carnian mud-poor sandstones were deposited at the base of the slope and the Norian thin-bedded turbidites were upper to mid-slope deposits. The continental margin was affected by tectonism and was uplifted in the latest Triassic–earliest Jurassic, possibly due to the initiation of the southward translation of the Arctic Alaska–Chukotka microplate. Following an Early–Middle Jurassic uplift of the area, sedimentation resumed in the Late Jurassic and earliest Cretaceous. Several syn-orogenic depressions (Rauchua, Pegtymel, Pevek, Myrgovaam and Kytepveem) developed on the south-western margin of the Chukotka microplate, and deposition in these basins included gravity flow deposits at various times. In both the Oxfordian–Kimmeridgian and Valanginian successions, gravity flow deposits included arkosic and subarkosic sandstones with a northern source area of granitoid complexes and deformed Triassic strata. The intervening Tithonian–Berriasian gravity flow deposits consisted mainly of thin-bedded turbidites. These sediments had a southern source, which included a volcanic arc that had accreted to the southern margin of the Chukotka microplate.
{"title":"Gravity flow deposits in Mesozoic sediments of Chukotka microplate (North-East Russia)","authors":"Marianna I. Tuchkova, Elena V. Vatrushkina, Sergey D. Sokolov","doi":"10.1002/dep2.269","DOIUrl":"10.1002/dep2.269","url":null,"abstract":"<p>In the Mesozoic succession of the Anyui–Chukotka fold system (North-East Russia), five stratigraphic intervals were recognised that have an abundance of gravity flow deposits. These are the Olenekian (Lower Triassic), Upper Carnian, Upper Norian, Oxfordian–Kimmeridgian and Valanginian. The Triassic gravity flow deposits formed on the south-facing, passive margin of the Chukotka microplate and consist of greywackes and lithic arenites. Palaeocurrent data indicate that the flows were directed towards the south-east. The Olenekian gravity flow units consist of clast-rich sandstone deposited on the continental slope, and clast-poor sandstone deposited at the base of the slope. Upper Carnian mud-poor sandstones were deposited at the base of the slope and the Norian thin-bedded turbidites were upper to mid-slope deposits. The continental margin was affected by tectonism and was uplifted in the latest Triassic–earliest Jurassic, possibly due to the initiation of the southward translation of the Arctic Alaska–Chukotka microplate. Following an Early–Middle Jurassic uplift of the area, sedimentation resumed in the Late Jurassic and earliest Cretaceous. Several syn-orogenic depressions (Rauchua, Pegtymel, Pevek, Myrgovaam and Kytepveem) developed on the south-western margin of the Chukotka microplate, and deposition in these basins included gravity flow deposits at various times. In both the Oxfordian–Kimmeridgian and Valanginian successions, gravity flow deposits included arkosic and subarkosic sandstones with a northern source area of granitoid complexes and deformed Triassic strata. The intervening Tithonian–Berriasian gravity flow deposits consisted mainly of thin-bedded turbidites. These sediments had a southern source, which included a volcanic arc that had accreted to the southern margin of the Chukotka microplate.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":"10 1","pages":"195-212"},"PeriodicalIF":2.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}