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Didier Neraudeau - One of the best experts on this subject based on the ideXlab platform.
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palynological assemblage from the lower Cenomanian plant bearing lagerstatte of jaunay clan ormeau saint denis vienne western france stratigraphic and paleoenvironmental implications
Review of Palaeobotany and Palynology, 2019Co-Authors: Alexis Licht, Didier Neraudeau, Aude Cincotta, David J Batten, Pauline Depuydt, Geraldine Garcia, Xavier ValentinAbstract:Abstract We describe here the palynological content from the lower Cenomanian plant-rich site of Jaunay-Clan (Vienne, western France), a site that previously yielded exceptional leaf impressions. Altogether, 184 species of palynomorphs have been identified, and two palynological intervals were recognized in the sedimentary sequence. The lower interval is characterized by the taxonomical and numerical dominance of spores of Gleicheniaceae, Cyatheales, and Anemiaceae, while the upper interval is characterized by an abrupt increase in the abundance of Classopollis and the appearance of dinocysts. This shift in the palynological composition, coupled with paleobotanical observations, is interpreted as reflecting a transition from a calm freshwater environment, with occasional droughts to an environment more open to very occasional marine inputs, such as an inner lagoon. The association of Tehamadinium coummia, Trichodinium spinosum, Tricolpites nemejcii, Retitricolporites decorosus, and Microreticulatiporites sacalii, coupled with the absence of Normapolles pollen grains, suggests that the Jaunay-Clan assemblage is early Cenomanian in age, corroborating the previous determination based on lithological and paleontological proxies. However, the Jaunay-Clan palynoflora is considered to be slightly younger than the numerous earliest Cenomanian assemblages described from Charente-Maritime, owing to its resemblance with mid-lower Cenomanian palynofloras from western France. The paleoflora and palynoflora from Jaunay-Clan are similar to other assemblages found in the upper Albian of Spain (Teruel Province), and in the Cenomanian of France and Czech Republic (Peruc-Korycany Formation, La Buzinie, Archingeay). The combined Jaunay-Clan palynoflora and paleoflora is considered to be the most diversified Cenomanian paleobotanical-palynological assemblage described so far in Western Europe.
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vertebrate remains from the Cenomanian late cretaceous plant bearing lagerstatte of puy puy charente maritime france
Cretaceous Research, 2013Co-Authors: Romain Vullo, Didier Neraudeau, Eric DepreAbstract:The vertebrate remains from the early Cenomanian Lagerstatte of Puy-Puy (Tonnay-Charente, Charente- Maritime, France) are described. They consist of two hybodont shark egg capsules (Palaeoxyris sp.) and a single isolated body contour feather. The hybodont shark Tribodus is regarded as the most likely producer of the egg capsules, while the feather belonged to an indeterminate (avian or non-avian) theropod. These rare specimens are the first vertebrate fossils recovered from the plant-bearing clay of Puy-Puy and add to the short faunal list of the locality, thus providing important information for the palaeoecological reconstruction of this mid-Cretaceous paralic Lagerstatte. The fossils described here represent the first Cenomanian occurrence of Palaeoxyris and one of the very few records of Cenomanian feathers.
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Vertebrate remains from the Cenomanian (Late Cretaceous) plantbearing Lagerstätte of Puy-Puy (Charente-Maritime, France)
Cretaceous Research, 2013Co-Authors: Romain Vullo, Didier Neraudeau, Eric DepreAbstract:The vertebrate remains from the early Cenomanian Lagerstätte of Puy-Puy (Tonnay-Charente, Charente- Maritime, France) are described. They consist of two hybodont shark egg capsules (Palaeoxyris sp.) and a single isolated body contour feather. The hybodont shark Tribodus is regarded as the most likely producer of the egg capsules, while the feather belonged to an indeterminate (avian or non-avian) theropod. These rare specimens are the first vertebrate fossils recovered from the plant-bearing clay of Puy-Puy and add to the short faunal list of the locality, thus providing important information for the palaeoecological reconstruction of this mid-Cretaceous paralic Lagerstätte. The fossils described here represent the first Cenomanian occurrence of Palaeoxyris and one of the very few records of Cenomanian feathers.
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Anuran and squamate remains from the Cenomanian (Late Cretaceous) of Charentes, western France
Journal of Vertebrate Paleontology, 2011Co-Authors: Romain Vullo, Jean-claude Rage, Didier NeraudeauAbstract:New remains of an anuran and various squamate reptiles have been recovered from Cenomanian paralic deposits of Charentes (southwestern France). Remains are not abundant, yet they make up one of the most diverse Cenomanian assemblages and the most diverse one from Europe. Nine or 10 taxa are present. Precise taxonomic assignment of most of them is not always possible, even at family level; however, the mosasauroid Carentonosaurus mineaui, the snake Simoliophis rochebrunei, as well as a possible dolichosaurid lizard are identified. At least two taxa are new, but they cannot be named on the basis of the available material. Among the fossils are an anuran and terrestrial lizards that rank among the very scarce ones from the Cenomanian. In addition, three distinct snakes are among the oldest ones. The faunas from the Cenomanian of Charentes are mixtures of terrestrial and predominantly marine taxa.
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Intramarginal veined Lauraceae leaves from the Albian-Cenomanian of Charente-Maritime (Western France)
Palaeontology, 2009Co-Authors: C. Coiffard, Frédéric Thévenard, Mélanie Thiébaut, Jiri Kvacek, Didier NeraudeauAbstract:Eucalyptolaurus depreii gen. et sp. nov. is proposed for angiosperm leaves newly collected from uppermost Albian lowermost Cenomanian of Charente-Maritime (western France). They consist of simple, narrow, elongate laminas with entire margins and intramarginal veins. The epidermal cells of adaxial cuticle shows small, rounded, blunt papillae outward that protrude inward and fuse together as rolls along and parallel to the margins, while the adaxial cuticle bears brachyparacytic stomatal apparatus that exhibit sunken guard cells and hair bases consisting of a thick-walled pore surrounded by radially arranged differentiated cells. Resin bodies occur inside the mesophyll. These characters closely resemble the lauroid taxa 'Myrtophyllum' and Pandemophyllum from the Cenomanian of the Czech Republic and Dakota (USA) respectively. The narrow angle of basilaminar secondaries and the whole suite of features in the guard cells (sunken guard cells embedded into subsidiary cells and stomatal ledges) strongly support close affinity with the Lauraceae. From the Cenomanian lauraceous reproductive organs and their related leaves already showed high disparity and diversity. In addition they displayed a broad ecological range from freshwater floodplains to brackish swamps. This combined to high diversity of reproductive organs suggest ecological radiation of Lauraceae by the Cenomanian.
Romain Vullo - One of the best experts on this subject based on the ideXlab platform.
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The first Gondwanan borioteiioid lizard and the mid-Cretaceous dispersal event between North America and Africa
The Science of Nature, 2018Co-Authors: Romain Vullo, Jean-claude RageAbstract:Borioteiioidea are an enigmatic group of Cretaceous lizards widely distributed in northern continents (Laurasia). Here, we describe the first borioteiioid lizard from Gondwana, represented by a new species of the polyglyphanodontine genus Bicuspidon , B. hogreli sp. nov., from the Cenomanian Kem Kem beds of Morocco. The discovery of Bicuspidon hogreli sp. nov., which is one of the oldest known member of Polyglyphanodontini, challenges previous assumptions on the center of origin and dispersal of the group. In addition, the known distribution of Bicuspidon (Cenomanian of Utah and Morocco, and Santonian–Maastrichtian of eastern Europe) suggests a complex palaeobiogeographical history for the genus. The existence of a terrestrial dispersal route persisting during the whole Early Cretaceous between North America and Africa is hypothesized to explain some similarities observed between the Cenomanian squamate assemblages of these two continents. Alternatively, dispersal between the two landmasses may have occurred by transatlantic rafting. During the Cenomanian–Santonian interval, Bicuspidon colonized the European archipelago probably from North Africa, like many “Eurogondwanan” taxa.
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vertebrate remains from the Cenomanian late cretaceous plant bearing lagerstatte of puy puy charente maritime france
Cretaceous Research, 2013Co-Authors: Romain Vullo, Didier Neraudeau, Eric DepreAbstract:The vertebrate remains from the early Cenomanian Lagerstatte of Puy-Puy (Tonnay-Charente, Charente- Maritime, France) are described. They consist of two hybodont shark egg capsules (Palaeoxyris sp.) and a single isolated body contour feather. The hybodont shark Tribodus is regarded as the most likely producer of the egg capsules, while the feather belonged to an indeterminate (avian or non-avian) theropod. These rare specimens are the first vertebrate fossils recovered from the plant-bearing clay of Puy-Puy and add to the short faunal list of the locality, thus providing important information for the palaeoecological reconstruction of this mid-Cretaceous paralic Lagerstatte. The fossils described here represent the first Cenomanian occurrence of Palaeoxyris and one of the very few records of Cenomanian feathers.
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Vertebrate remains from the Cenomanian (Late Cretaceous) plantbearing Lagerstätte of Puy-Puy (Charente-Maritime, France)
Cretaceous Research, 2013Co-Authors: Romain Vullo, Didier Neraudeau, Eric DepreAbstract:The vertebrate remains from the early Cenomanian Lagerstätte of Puy-Puy (Tonnay-Charente, Charente- Maritime, France) are described. They consist of two hybodont shark egg capsules (Palaeoxyris sp.) and a single isolated body contour feather. The hybodont shark Tribodus is regarded as the most likely producer of the egg capsules, while the feather belonged to an indeterminate (avian or non-avian) theropod. These rare specimens are the first vertebrate fossils recovered from the plant-bearing clay of Puy-Puy and add to the short faunal list of the locality, thus providing important information for the palaeoecological reconstruction of this mid-Cretaceous paralic Lagerstätte. The fossils described here represent the first Cenomanian occurrence of Palaeoxyris and one of the very few records of Cenomanian feathers.
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Anuran and squamate remains from the Cenomanian (Late Cretaceous) of Charentes, western France
Journal of Vertebrate Paleontology, 2011Co-Authors: Romain Vullo, Jean-claude Rage, Didier NeraudeauAbstract:New remains of an anuran and various squamate reptiles have been recovered from Cenomanian paralic deposits of Charentes (southwestern France). Remains are not abundant, yet they make up one of the most diverse Cenomanian assemblages and the most diverse one from Europe. Nine or 10 taxa are present. Precise taxonomic assignment of most of them is not always possible, even at family level; however, the mosasauroid Carentonosaurus mineaui, the snake Simoliophis rochebrunei, as well as a possible dolichosaurid lizard are identified. At least two taxa are new, but they cannot be named on the basis of the available material. Among the fossils are an anuran and terrestrial lizards that rank among the very scarce ones from the Cenomanian. In addition, three distinct snakes are among the oldest ones. The faunas from the Cenomanian of Charentes are mixtures of terrestrial and predominantly marine taxa.
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Cenomanian vertebrate assemblages from southwestern France: a new insight into the European mid-Cretaceous continental fauna
Cretaceous Research, 2008Co-Authors: Romain Vullo, Didier NeraudeauAbstract:Cenomanian paralic deposits of Charentes (southwestern France) have yielded abundant vertebrate microremains, including rather diversified continental taxa (e.g., frogs, turtles, crocodilians, dinosaurs, pterosaurs, lizards, and mammals). In this short report, the succession of faunal assemblages observed is briefly described in relation to palaeoenvironmental change resulting from the Cenomanian-early Turonian transgressive episode. Continental forms occur commonly in estuarine and shallow marine rocks of the lower part of the Cenomanian stage, but seem to be lacking in younger strata deposited in more open marine settings. Among an unexpected biodiversity, several non-marine groups (e.g., ziphodont crocodilians, carcharodontosaurid and troodontid dinosaurs, marsupial-like mammals) are recorded for the first time in the lower Upper Cretaceous of Europe, thus providing new palaeobiogeographical indications for this poorly documented part of the world.
Emad Nagm - One of the best experts on this subject based on the ideXlab platform.
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Ammonite zonal scheme for the upper Cenomanian of the southern Tethys margin from Jordan to Tunisia, with palaeobiogeographic implications
Journal of African Earth Sciences, 2019Co-Authors: Emad Nagm, Sherif Farouk, Fayez Ahmad, Zaineb ElamriAbstract:Abstract An ammonite zonal scheme is applied for the upper Cenomanian carbonate/siliciclastic successions of the southern Tethys margin exposed in Jordan, Egypt, Libya and Tunisia. Different palaeobiogeographic distributions of the upper Cenomanian ammonites in the Middle East and North Africa resulted in different zonal schemes. Here, we traced the contemporaneous ammonite occurrences from different provinces along the southern Tethys margin in order to introduce one valid zonal scheme for the area from Jordan to Tunisia. The applied scheme consists of the following three ammonite zones that are widely recorded in the Tethyan realm: the lower upper Cenomanian Neolobites vibrayeanus, the middle upper Cenomanian Euomphaloceras septemseriatum and the uppermost Cenomanian Pseudaspidoceras pseudonodosoides zones. The palaeobiogeographic distribution of the studied ammonites presents a significant relation to the palaeowater depth and sedimentary facies. Furthermore, upper Cenomanian ammonites of the southern Tethys margin tend to be geographically associated as ecologically related communities. Globally, the studied ammonites reflect a change from an expanded Tethyan bioprovince in the early and middle late Cenomanian to a cosmopolitan distribution during the latest Cenomanian. The rapid sea-level rise and the major palaeoenvironmental perturbations that dominate globally during the late Cenomanian time may played an important role in these palaeobiogeographic distribution patterns observed for the upper Cenomanian ammonites in Jordan, Egypt, Libya and Tunisia.
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The Cenomanian–Turonian boundary in Jordan: Ammonite biostratigraphy and faunal turnover
Geobios, 2017Co-Authors: Emad Nagm, Sherif Farouk, Fayez AhmadAbstract:Abstract Well-exposed fossiliferous Upper Cenomanian–Lower Turonian marine sedimentary rocks are present in west-central Jordan. Ammonites serve as an important faunal marker for this interval and can be used to subdivide the Cenomanian–Turonian transition into two upper Cenomanian biozones (Neolobites vibrayeanus and Vascoceras cauvini) and two lower Turonian biozones (Vascoceras proprium and Choffaticeras segne). A revised stratigraphic range of the Vascoceras cauvini Zone in the study area is proposed, consisting of the Metoicoceras geslinianum and Neocardioceras juddii zones of the standard zonation. Based on intercontinental biostratigraphic correlation, a minor unconformity appears to be present around the Cenomanian–Turonian boundary, and a part of the lower Turonian is probably missing. In addition, a faunal turnover is recorded in the uppermost Cenomanian, marked by the disappearance of most of the Cenomanian taxa, including Costagyra olisiponensis (Sharpe), Ceratostreon flabellatum (Goldfuss), Ilymatogyra africana (Lamarck), Rhynchostreon suborbiculatum (Lamarck), Harpagodes nodosus (Sowerby), and Heterodiadema libycum (Desor). This bioevent is thought to be an effect of the Oceanic Anoxic Event OAE 2; the dramatic shifts in species richness and diversity spanning the Cenomanian–Turonian boundary in the study area occurred in response to the major paleoclimatic and paleoenvironmental perturbations prevailing at that time. The stratigraphic and paleontological patterns studied in Jordan are very similar to those recorded in Egypt in terms of litho- and biostratigraphy, event stratigraphy, and macroinvertebrate content, suggesting the presence of uniform triggering mechanisms and bio-sedimentary responses in the Upper Cretaceous basins of the Middle East and providing clues for a high-resolution correlation between the two areas.
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stratigraphic significance of rapid faunal change across the Cenomanian turonian boundary in the eastern desert egypt
Cretaceous Research, 2015Co-Authors: Emad NagmAbstract:Abstract A significant and rapid faunal change across the Cenomanian–Turonian boundary in the Eastern Desert of Egypt has been recognized by reconstructing the stratigraphic ranges of macroinvertebrates within the upper Cenomanian–lower Turonian Galala and Abu Qada formations. The faunal change initiated with a considerable loss of taxa during the late Cenomanian at the top of the Neolobites vibrayeanus ammonite zone, coinciding with sequence boundary SB Ce 5, ∼400 ka before the Cenomanian–Turonian boundary (93.9 Ma). Only 10% of the taxa that existed during the late Cenomanian have been recorded from lower Turonian strata. The changes in the macroinvertebrate faunas continued across the Cenomanian–Turonian boundary and new faunal associations evolved after the earliest Turonian Vascoceras proprium ammonite zone of (∼200 ka after the Cenomanian–Turonian boundary). Therefore, the crisis that caused this faunal change around the Cenomanian–Turonian boundary over approximately 600 ka. The timing of the macrofaunal change recognized in the study area completely overlaps with the well-known Oceanic Anoxic Event (OAE) 2 and most probably it is one of the effects of the major environmental perturbations (critical warming, high atmospheric CO 2 concentration, and ocean water acidification) associated with this event. In addition, the sequence-stratigraphic analysis shows strong correlation exists between pattern of first and last occurrences of macroinvertebrate faunas and sea-level changes. Therefore, the oceanographic changes (rapid sea-level rise) may have also contributed to the Cenomanian–Turonian faunal change in the study area.
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Stratigraphic significance of rapid faunal change across the Cenomanian–Turonian boundary in the Eastern Desert, Egypt
Cretaceous Research, 2015Co-Authors: Emad NagmAbstract:Abstract A significant and rapid faunal change across the Cenomanian–Turonian boundary in the Eastern Desert of Egypt has been recognized by reconstructing the stratigraphic ranges of macroinvertebrates within the upper Cenomanian–lower Turonian Galala and Abu Qada formations. The faunal change initiated with a considerable loss of taxa during the late Cenomanian at the top of the Neolobites vibrayeanus ammonite zone, coinciding with sequence boundary SB Ce 5, ∼400 ka before the Cenomanian–Turonian boundary (93.9 Ma). Only 10% of the taxa that existed during the late Cenomanian have been recorded from lower Turonian strata. The changes in the macroinvertebrate faunas continued across the Cenomanian–Turonian boundary and new faunal associations evolved after the earliest Turonian Vascoceras proprium ammonite zone of (∼200 ka after the Cenomanian–Turonian boundary). Therefore, the crisis that caused this faunal change around the Cenomanian–Turonian boundary over approximately 600 ka. The timing of the macrofaunal change recognized in the study area completely overlaps with the well-known Oceanic Anoxic Event (OAE) 2 and most probably it is one of the effects of the major environmental perturbations (critical warming, high atmospheric CO 2 concentration, and ocean water acidification) associated with this event. In addition, the sequence-stratigraphic analysis shows strong correlation exists between pattern of first and last occurrences of macroinvertebrate faunas and sea-level changes. Therefore, the oceanographic changes (rapid sea-level rise) may have also contributed to the Cenomanian–Turonian faunal change in the study area.
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stable isotope stratigraphy of the Cenomanian turonian upper cretaceous boundary event ctbe in wadi qena eastern desert egypt
Journal of African Earth Sciences, 2014Co-Authors: Emad Nagm, Gamal Elqot, Markus WilmsenAbstract:A high-resolution δ13C isotope record from Cenomanian–Turonian boundary interval of shallow marine successions in Egypt is presented. The δ13C curves show the typical features of the globally documented Cenomanian–Turonian positive excursion, including three of the main positive isotope peaks defining the Cenomanian–Turonian Boundary Event (CTBE). Based on high-resolution ammonite biostratigraphy, the CTBE started in the study area above the Late Cenomanian Neolobites vibrayeanus Zone within the Galala Formation, directly above the global sequence boundary Cenomanian 5 (SB Ce 5). A stratigraphic gap at that level cuts out the lower a-peak of the CTBE. The Cenomanian–Turonian boundary is located within the upper part of the positive excursion between carbon excursion peaks c and d, coinciding with the boundary between the Late Cenomanian Vascoceras cauvini and the Early Turonian Vascoceratid zones. The CTBE ended up-section of peak d, at the base of the Choffaticeras spp. Zone. The amplitude of the positive δ13C excursion in Egypt is very high (reaching 6.5‰ vs. V-PDB) and largely matches curves of European standard sections and others localities from different basins. Furthermore, the Lower Turonian Holywell Isotope Event, an important marker within the lowermost Turonian, has tentatively been recognized. The positive carbon stable isotope curves presented herein represent the outreach of the oceanic anoxic event (OAE) 2 in shallow-water nearshore sequences.
François Raisson - One of the best experts on this subject based on the ideXlab platform.
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Stripping back the modern to reveal the Cenomanian-Turonian climate and temperature gradient underneath
Climate of the Past, 2020Co-Authors: Marie Laugié, Yannick Donnadieu, Jean-baptiste Ladant, J. Green, Laurent Bopp, François RaissonAbstract:During past geological times, the Earth experienced several intervals of global warmth, but their driving factors remain equivocal. A careful appraisal of the main processes controlling past warm events is essential to inform future climates and ultimately provide decision makers with a clear understanding of the processes at play in a warmer world. In this context, intervals of greenhouse climates , such as the thermal maximum of the Cenomanian-Turonian (∼ 94 Ma) during the Cretaceous Period, are of particular interest. Here we use the IPSL-CM5A2 (IPSL: In-stitut Pierre et Simon Laplace) Earth system model to unravel the forcing parameters of the Cenomanian-Turonian greenhouse climate. We perform six simulations with an in-cremental change in five major boundary conditions in order to isolate their respective role on climate change between the Cenomanian-Turonian and the preindustrial. Starting with a preindustrial simulation, we implement the following changes in boundary conditions: (1) the absence of polar ice sheets, (2) the increase in atmospheric pCO 2 to 1120 ppm, (3) the change in vegetation and soil parameters, (4) the 1 % decrease in the Cenomanian-Turonian value of the solar constant and (5) the Cenomanian-Turonian palaeo-geography. Between the preindustrial simulation and the Cre-taceous simulation, the model simulates a global warming of more than 11 • C. Most of this warming is driven by the increase in atmospheric pCO 2 to 1120 ppm. Palaeogeo-graphic changes represent the second major contributor to global warming, whereas the reduction in the solar constant counteracts most of geographically driven warming. We further demonstrate that the implementation of Cenomanian-Turonian boundary conditions flattens meridional temperature gradients compared to the preindustrial simulation. Interestingly , we show that palaeogeography is the major driver of the flattening in the low latitudes to midlatitudes, whereas pCO 2 rise and polar ice sheet retreat dominate the high-latitude response.
Markus Wilmsen - One of the best experts on this subject based on the ideXlab platform.
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The Albian–Cenomanian transition and Oceanic Anoxic Event 1d – an example from the Boreal Realm
Sedimentology, 2017Co-Authors: André Bornemann, Markus Wilmsen, Jochen Erbacher, Matthias Heldt, Tina Kollaske, Nathalie Lübke, Stefan Huck, Nele M. Vollmar, Thomas WonikAbstract:The upper Albian to lower Cenomanian interval in the Hanover area (Germany) is characterized by a well-developed lithological transition from upper Albian monotonous (marly) claystones of several hundred metres thickness, which become enriched in biosilica in the topmost Albian, to increasingly CaCO3-rich marls and limestones in the lower and middle Cenomanian. This study presents a new 165-m-thick composite record spanning the latest Albian to mid-early Cenomanian (ca 103.0 to 97.5 Ma) based on two core drillings at Anderten in the central Lower Saxony Basin (east of Hanover), which is a sub-basin of the North German Basin. Due to the lack or delayed occurrences of Tethyan biostratigraphic markers for the late Albian and early Cenomanian in the Boreal Realm, the definition of the Albian–Cenomanian boundary, as based on the lowest occurrence of Thalmanninella globotruncanoides, is not applicable. In order to overcome this issue an integrated biostratigraphic–chemostratigraphic approach has been employed. In addition to biostratigraphy (calcareous nannofossils, ostracods, planktonic foraminifera and inoceramids), the Anderten succession has been studied using sedimentary geochemistry [CaCO3, total organic carbon (TOC), δ13C and δ18O], γ-ray logging and X-ray fluorescence core scanning. This approach enabled successful correlation of the composite Anderten record to European reference sections in England, south-east France and Italy as well as to further low-resolution records from the Lower Saxony Basin (Wunstorf and Konrad 101 core). This work has made it possible to identify the δ13Ccarb expression of: (i) the Oceanic Anoxic Event 1d; (ii) the Albian–Cenomanian boundary interval; and (iii) potentially the Lower Cenomanian Event(s). Chemostratigraphic age assignments are supported by biostratigraphic results. Calcareous nannofossils indicate an extended Upper Cretaceous 0 (UC0) zone (upper Albian) up to UC2 (upper lower Cenomanian) and the occurrence of the ostracod Physocythere steghausi supports an early Cenomanian age for most of the upper part of the composite record. Notably, influxes of the planktonic foraminifer Thalmanninella aff. reicheli have previously been described from this area and the first appearance of this taxon is usually used to define the base of the middle Cenomanian Substage. However, findings from the Anderten cores and elsewhere suggest that this taxon has an apparently earlier first appearance, questioning previous age assignments from the Boreal Realm solely based on planktonic foraminifera. Due to both moderately well-preserved microfossils and high sedimentation rates the drilled succession of Anderten is considered as a potential Boreal reference section for the Albian–Cenomanian transition. This article is protected by copyright. All rights reserved.
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stable isotope stratigraphy of the Cenomanian turonian upper cretaceous boundary event ctbe in wadi qena eastern desert egypt
Journal of African Earth Sciences, 2014Co-Authors: Emad Nagm, Gamal Elqot, Markus WilmsenAbstract:A high-resolution δ13C isotope record from Cenomanian–Turonian boundary interval of shallow marine successions in Egypt is presented. The δ13C curves show the typical features of the globally documented Cenomanian–Turonian positive excursion, including three of the main positive isotope peaks defining the Cenomanian–Turonian Boundary Event (CTBE). Based on high-resolution ammonite biostratigraphy, the CTBE started in the study area above the Late Cenomanian Neolobites vibrayeanus Zone within the Galala Formation, directly above the global sequence boundary Cenomanian 5 (SB Ce 5). A stratigraphic gap at that level cuts out the lower a-peak of the CTBE. The Cenomanian–Turonian boundary is located within the upper part of the positive excursion between carbon excursion peaks c and d, coinciding with the boundary between the Late Cenomanian Vascoceras cauvini and the Early Turonian Vascoceratid zones. The CTBE ended up-section of peak d, at the base of the Choffaticeras spp. Zone. The amplitude of the positive δ13C excursion in Egypt is very high (reaching 6.5‰ vs. V-PDB) and largely matches curves of European standard sections and others localities from different basins. Furthermore, the Lower Turonian Holywell Isotope Event, an important marker within the lowermost Turonian, has tentatively been recognized. The positive carbon stable isotope curves presented herein represent the outreach of the oceanic anoxic event (OAE) 2 in shallow-water nearshore sequences.
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Cenomanian Acanthoceratoidea (Cretaceous Ammonoidea) from the Koppeh Dagh, NE Iran: taxonomy and stratigraphic implications
Acta Geologica Polonica, 2011Co-Authors: Abdolmajid Mosavinia, Markus WilmsenAbstract:Seven species of the acanthoceratoidean genera Forbesiceras Kossmat, 1897, Mantelliceras Hyatt, 1903, Acanthoceras Neumayr, 1875 and Cunningtoniceras Collignon, 1937 are described and illustrated from the upper (i.e., Cenomanian) part of the Aitamir Formation of the Koppeh Dagh, northeast Iran. The mantelliceratines were collected from lower Cenomanian silty shales while the rest of the fauna stems from lower middle Cenomanian glauconitic sandstones in the upper part of the formation. the ammonite association allows recognition of the lower lower Cenomanian Mantelliceras mantelli and the lower middle Cenomanian Acanthoceras rhotomagense zones. the upper lower Cenomanian M. dixoni Zone is not proven by its index but is most likely represented by a unit of fossil-poor shales intercalated between the two above-mentioned zones. the lowermost middle Cenomanian Cunningtoniceras inerme Zone, however, is potentially at least partly missing due to a major sea-level fall and lowstand in the latest Early to earliest middle Cenomanian. A preliminary sequence stratigraphic interpretation of the successions suggests the presence of lower Cenomanian sequence boundaries sb Ce 1–3. The Aitamir Formation is truncated along a major regional unconformity at the base of the overlying Abderaz Formation (Turonian–Coniacian). The upper Cenomanian and most likely also (parts of) the lower Turonian are missing. This major unconformity has a tectonic origin as it deviates from the eustatic sea-level trend which was very high at this time. Furthermore, contemporaneous tectonic unconformities are also known from Central Iran and may have their origins in rotational movements of the Central-East Iranian microcontinent.
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Facies pattern and sea-level dynamics of the early Late Cretaceous transgression: a case study from the lower Danubian Cretaceous Group (Bavaria, southern Germany)
Facies, 2010Co-Authors: Markus Wilmsen, Birgit Niebuhr, Patrick Chellouche, Thomas Pürner, Michael KlingAbstract:The facies development and onlap pattern of the lower Danubian Cretaceous Group (Bavaria, southern Germany) have been evaluated based on detailed logging, subdivision, and correlation of four key sections using an integrated stratigraphic approach as well as litho-, bio-, and microfacies analyses. Contrary to statements in the literature, the transgressive onlap of the Regensburg Formation started in the Regensburg–Kelheim area already in the early Early Cenomanian Mantelliceras mantelli ammonite Zone and not in the Late Cenomanian. In the Early Cenomanian, nearshore glauconitic-bioclastic sandstones prevailed (Saal Member), followed by Middle to lower Upper Cenomanian mid-shelf siliceous carbonates intercalated with fine-sandy to silty marls (Bad Abbach Member). Starting in the mid-Late Cenomanian ( Metoicoceras geslinianum ammonite Zone), a considerable deepening pulse during the Cenomanian–Turonian Boundary Event (CTBE) initiated the deposition of the deeper shelf silty marls of the Eibrunn Formation, which range into the early Early Turonian. During the CTBE transgression, also the proximal Bodenwöhrer Senke (ca. 40 km NE of Regensburg) was flooded, indicated by the onlap of the Regensburg Formation onto Variscan granites of the Bohemian Massif, overlain by a thin tongue of lowermost Turonian Eibrunn Formation. A detailed record of the positive δ^13C excursion of the global Oceanic Anoxic Event (OAE) 2 has been retrieved from this shallow-water setting. An integrated approach of bio-, event-, carbon stable isotope and sequence stratigraphy was applied to correlate the sections and to decipher the dynamics of this overall transgressive depositional system. The Cenomanian successions show five prominent unconformities, which correlate with those being known from basins in Europe and elsewhere, indicating their eustatic origin. The rate of sea-level rise during the CTBE suggests glacio-eustasy as a driving mechanism for Late Cenomanian sea-level changes. The Regensburg and Eibrunn formations of the lower Danubian Cretaceous Group are highly diachronous lithostratigraphic units. Their regional distribution and northeast-directed onlap pattern onto the southwestern margin of the Bohemian Massif can readily be explained by the lateral movements of roughly coast-parallel (i.e., NW/SE-trending) facies belts of a graded shelf system transgressing on a northeastward-rising substrate. It took the Cenomanian coastline ca. 6 Ma to transgress from southwest of Regensburg to the topographically elevated granite cliffs southeast of Roding in the Bodenwöhrer Senke (=60 km distance).
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Integrated stratigraphy of the upper Lower – lower Middle Cenomanian of northern Germany and southern England
Acta Geologica Polonica, 2007Co-Authors: Markus WilmsenAbstract:A high-resolution stratigraphic calibration of the upper Lower (upper Mantelliceras dixoni Zone) and lower Middle Cenomanian (Cunningtoniceras inerme Zone and lower Acanthoceras rhotomagense Zone) based on an integrated analysis of macrofossil biostratigraphy, event, cyclo-, stable-isotope and sequence stratigraphy of northern German and southern England key sections is presented. Classic event stratigraphy has a good potential in refining biostratigraphic correlations as most of the classic bioevents are isochronous within the integrated stratigraphy. Many lithological event beds such as marker marls can be incorporated into the cyclo- and sequence stratigraphic framework, explaining their significance in interregional correlation. The best stratigraphic resolution provides the cyclostratigraphy based on the typical Cenomanian marl-limestone couplets and their stacking pattern, inferred to reflect orbital forcing of the Milankovitch frequency band: detailed bed-by-bed correlation of couplets (precession cycle, ca. 20 kyr) allows a stratigraphic calibration within ~10 kyr time slices. Conspicuous marker marl beds embrace bundles of ~five couplets and are related to the short eccentricity (100 kyr) cycle. However, for the upper Lower Cenomanian ( dixoni Zone) it appears that the existing couplet scale is incomplete. Sequence stratigraphic analysis demonstrates that the investigated interval comprises the maximum flooding and highstand interval of an Early Cenomanian sequence, capped by a significant late dixoni Zone sequence boundary, followed by uppermost Lower to Middle Cenomanian lowstand and transgressive deposits grading into a Middle Cenomanian maximum flooding zone (“calcimetry break”). Carbon stable-isotope values are stable around 2‰ vs. V-PDB within the mid- and late dixoni Zone, related to equilibrium conditions during maximum flooding and highstand conditions of sea-level. The latest Early to earliest Middle Cenomanian sea-level fall and lowstand was accompanied by a negative δ 13 C excursion of ca. 0.4 ‰ in couplets B34-B40 (Lower-Middle Cenomanian boundary isotope Event, LMCE, new name) followed by a rise of 0.4–0.6‰ δ 13 C in couplets B41-C2 during the early transgressive systems tract (Middle Cenomanian δ 13 C excursion MCE 1). These observations support the interpretation that the δ 13 C signal is a good proxy for (eustatic) sea-level changes. The LMCE is suggested as a proxy marker for the base of the Middle Cenomanian Substage.