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Emmanuel Fara - One of the best experts on this subject based on the ideXlab platform.
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uncommon preservation of dinosaur footprints in a tidal breccia eubrontes giganteus from the early jurassic mongisty tracksite of aveyron southern france
Geological Magazine, 2021Co-Authors: Jeandavid Moreau, Jacques Sciau, Georges Gand, Emmanuel FaraAbstract:A recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a doloMudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the Mudflat of the Causses Basin was sporadically affected by large Mud Flows that reworked and redeposited Mudstone intraclasts coming from the erosion of upstream, dry and partially lithified Mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.
Jean-paul Foucher - One of the best experts on this subject based on the ideXlab platform.
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Changes in seabed morphology, Mud temperature and free gas venting at the Håkon Mosby Mud volcano, offshore northern Norway, over the time period 2003–2006
Geo-Marine Letters, 2010Co-Authors: Jean-paul Foucher, Tomas Feseker, Stéphanie Dupré, Carla Scalabrin, François Harmegnies, Hervé NouzéAbstract:The Håkon Mosby Mud volcano is a 1.5-km-diameter geological structure located on the Southwest Barents Sea slope at a water depth of 1,270 m. High-definition seabed mapping of the Mud volcano has been carried out in 2003 and 2006. A comparative analysis of the bathymetry and backscatter maps produced from the two surveys shows subtle morphological changes over the entire crater of the Mud volcano, interpreted to be the consequence of Mud eruption events. Mud temperature measurements point to a persistently warm Mud at shallow depth in the crater. This is explained by upward fluid advection, rather than conductive cooling of Mud Flows. The small-scale spatial variability in the temperature distribution may be related to Mud outFlows or changes in the fluid flow regime. Furthermore, the locations of free gas venting observed in 2006 were found to differ from those of 2003. Our observations of overall similar topographic profiles across the Mud volcano in 2003 and 2006 suggest that eruption events would have been modest. Nevertheless, the data bring evidence of significant change in activity even over short time intervals of only 3 years. This may be a characteristic shared by other submarine Mud volcanoes, notably those considered to be in a quiescent stage.
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Spatial distribution of Mud Flows, chemoautotrophic communities, and biogeochemical habitats at Håkon Mosby Mud Volcano
Marine Geology, 2007Co-Authors: Kerstin Jerosch, Michael Schlüter, Jean-paul Foucher, A. G. Allais, Michael Klages, Christian EdyAbstract:Marine Mud volcanoes are significant source locations contributing to the marine methane cycle. Enhanced heat flow, unique chemoautotrophic communities, occurrence of massive gas hydrates and large gas plumes are direct evidences of elevated methane concentrations and the dynamic environment of Mud volcanoes. Related to the high concentrations and large inventories of CH4 in surface sediments only a fraction of the methane is exported to the bottom water. This is mainly due to chemoautotrophic communities oxidizing methane and proving a “microbial filter” reducing CH4 fluxes. Although these processes were studied for several Mud volcanoes still little is known about the spatial pattern and the areas covered by chemoautotrophic communities or by present Mud Flows. For this purposes the Hakon Mosby Mud Volcano (HMMV), which is located at the continental slope of the Barents Sea, was studied by several dives with the Remotely Operated Vehicle Victor6000. During these dives a high resolution microbathymetric map, with a footprint of 25×25 cm and a vertical resolution of better than 10 cm was derived. Furthermore, video streams of the bottom camera were converted into georeferenced mosaics, providing a detailed image about the spatial distribution of seafloor features as bacterial mats, pogonophorans, both indicating methane oxidation, or Mud Flows. Based on visual inspection of 2310 georeferenced mosaics covering an area of 46,160 m 2 , different biogeochemical habitats were identified and quantified on a m 2 basis. By application of geostatistic techniques as indicator kriging the distribution of different biogeochemical habitats was quantified and mapped for the entire HMMV. Considering the flat and hummocky area of HMMV, approximately 16% (115,165 m 2 ) of the flat centre is nearly void of any benthic communities. This area is considered as a region of high methane discharge into bottom water. An area of 5% (38,244 m 2 ), located in the south-eastern part, is densely inhabited by Beggiatoa. The hummocky outer part is colonised dominantly by pogonophoran tube worms (37.3%; 276,121 m 2 ) and only occasional by Beggiatoa. Source locations and drainage directions for current Mud Flows were identified by computation of trend surfaces and consideration of temperature data. This suggests that present Mud flow ascend close to the northern edge of the flat unit of HMMV, and that the drainage pattern of Mud Flows shifted from a westward to a south-south-eastern direction. © 2007 Elsevier B.V. All rights reserved.
Jutta Thielen - One of the best experts on this subject based on the ideXlab platform.
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operational early warning systems for water related hazards in europe
Environmental Science & Policy, 2012Co-Authors: Lorenzo Alfieri, Peter Salamon, Fredrik Wetterhall, Florian Pappenberger, Jutta ThielenAbstract:Abstract Preparedness towards natural hazards is a key factor in the reduction of their impact on the society. Recent international initiatives are fostering the development of a culture of risk prevention and the promotion of early warning systems. Numerical weather predictions have become the basis of several flood-related warning systems, enabling the detection of hazardous events with sufficient lead-time to prepare effective emergency and response plans. The objective of this paper is to review current European operational warning systems for water-related hazards induced by severe weather conditions. In details, it includes systems for detecting surface water flooding, flash floods, debris Flows, Mud Flows, rainfall-induced landslides, river floods and coastal floods. Technical features and capabilities of different systems are described, together with some noteworthy examples. The main strengths of each system type are highlighted and suggestions are provided for developing and further improving their overall skills in hazard detection and the mutual coordination.
Argant Alain - One of the best experts on this subject based on the ideXlab platform.
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La brèche à carnivores du Pléistocène moyen de Château (Saône-et-Loire, France)
Quaternaire, 2020Co-Authors: Argant Alain, Argant JacquelineAbstract:À Château (Saône-et-Loire, France), en 1863, à l’occasion de l’élargissement de la route D165 fut découverte une « prodigieuse quantité d’os d’ours et de lion des cavernes » dans un réseau karstique très ancien démantelé par l’érosion puis par les travaux de carrière du 19ème siècle. A l’époque aucune étude n’a été réalisée. Nous redécouvrons le site en 1968 et pratiquons des fouilles jusqu’en 2008. L’ours (Ursus deningeri) domine largement la faune de Château, mais la particularité de ce site est l’abondance de grands félins (Panthera gombaszogensis et Panthera spelaea fossilis). Un Canidé (Canis mosbachensis) et Arvicola cantiana pour la microfaune complètent la liste de faune pour l’Ensemble Nord. L’analyse pollinique indique un milieu tempéré froid pour les deux brèches et un paysage ouvert. Jusqu’ici, aucune datation absolue n’a pu être obtenue pour cet Ensemble Nord. La biochronologie permet cependant de dater la Brèche 4, la plus ancienne, du Pléistocène moyen ancien et les Brèches 2 et 3, les plus fossilifères, du Pléistocène moyen médian. Dans l’Ensemble Sud, plus récent, trois datations U/Th indiquent le MIS 6. L’Ensemble Sud correspond à un puits à cannelures vertical. Une ouverture latérale par érosion de la pente a permis la formation d’un éboulis de type aven enregistrant la présence d’une tanière d’hyène des cavernes. A la fin du Pléistocène moyen, plusieurs effondrements ont amené des coulées boueuses fossilifères comblant les vides du karst.In 1863, at Château (Saône-et-Loire, France) a widening of part of the D165 road revealed an enormous amount of bear and lion bones in an old karstic system completely destroyed, primarily by erosion, and later by quarrying in the 19th century. No study of the bones was done at the time of this discovery. We rediscovered the site in 1968 and new excavations were carried out there until 2008. Bear remains largely dominate the Château Breccia fossil assemblage, but the singularity of this site is the abundance of big cats (Panthera gombaszogensis et Panthera spelaea fossilis). A canid (Canis mosbachensis) and Arvicola cantiana for the microfauna complete the fauna list in the Ensemble Nord. A study of the fossil pollen indicates a cold temperate environment for the two breccias and suggests an open landscape. So far, no absolute dating could be obtained for the Ensemble Nord. Only the biochronology allows us to suggest a date of the Early Middle Pleistocene age for Breccia 4, the most ancient, and Median Middle Pleistocene for Breccia 2 and 3, the most fossiliferous. In the Ensemble Sud, more recent, three U/Th datings match with MIS 6. The Ensemble Sud corresponds to a vertical “puits à cannelures”. The lateral opening of the “puits” by erosion allowed the formation of an aven type scree that reveals the presence of a hyaena den. A series of underground rockslides enabled Mud Flows with fossils to fill the holes at the end of the Middle Pleistocene
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La brèche à Carnivores du Pléistocène moyen de Château (Saône-et-Loire, France)
Centre National de la Recherche Scientifique, 2018Co-Authors: Argant Alain, Jacqueline ArgantAbstract:International audienceIn 1863, at Château (Saône-et-Loire, France) a widening of part of the D165 road revealed an enormous amount of bear and lion bones in an old karstic system completely destroyed, primarily by erosion, and later by quarrying in the 19th century. No study of the bones was done at the time of this discovery. We rediscovered the site in 1968 and new excavations were carried out there until 2008. Bear remains largely dominated the Château Breccia fossil assemblage, but the characteristic peculiarity of this site is the abundance of big cats (Panthera gombaszogensis et Panthera spelaea fossilis). A canid (Canis mosbachensis) and Arvicola cantiana for the microfauna complete the fauna list in the Ensemble Nord. A study of the fossil pollen indicates a milieu of moderate cold for the two breccias and suggests an open landscape. So far, no absolute dating could be obtained for the Ensemble Nord. Only the biochronology allows us to suggest a date of the Early Middle Pleistocene age for Breccia 4, the most ancient, and Median Middle Pleistocene for Breccia 2 and 3, the most fossiliferous. In the Ensemble Sud, more recent, three U/Th datings match with MIS 6. The Ensemble Sud corresponds to a vertical "puits à cannelures". The lateral opening of the "puits" by erosion allowed the formation of an aven type scree which reveals the presence of a hyaena den. A series of underground rockslides enabled Mud Flows with fossils to fill the holes at the end of the Middle Pleistocene.À Château (Saône-et-Loire, France), en 1863, à l'occasion de l'élargissement de la route D165 fut découverte une "prodigieuse quantité d'os d'ours et de lion des cavernes" dans un réseau karstique très ancien démantelé par l'érosion puis par les travaux de carrière du 19ème siècle. A l'époque aucune étude n'a été réalisée. Nous redécouvrons le site en 1968 et pratiquons des fouilles jusqu'en 2008. L'ours (Ursus deningeri) domine largement la faune de Château, mais la particularité de ce site est l'abondance de grands félins (Panthera gombaszogensis et Panthera spelaea fossilis). Un Canidé (Canis mosbachensis) et Arvicola cantiana pour la microfaune complètent la liste de faune pour l’Ensemble Nord. L'analyse pollinique indique un milieu tempéré froid pour les deux brèches et un paysage ouvert. Jusqu'ici, aucune datation absolue n'a pu être obtenue pour cet Ensemble Nord. La biochronologie permet cependant de dater la Brèche 4, la plus ancienne, du Pléistocène moyen ancien et les Brèches 2 et 3, les plus fossilifères, du Pléistocène moyen médian. Dans l'Ensemble Sud, plus récent, trois datations U/Th indiquent le MIS 6. L’Ensemble Sud correspond à un puits à cannelures vertical. Une ouverture latérale par érosion de la pente a permis la formation d’un éboulis de type aven enregistrant la présence d’une tanière d'hyène des cavernes. A la fin du Pléistocène moyen, plusieurs effondrements ont amené des coulées boueuses fossilifères comblant les vides du karst
Jeandavid Moreau - One of the best experts on this subject based on the ideXlab platform.
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uncommon preservation of dinosaur footprints in a tidal breccia eubrontes giganteus from the early jurassic mongisty tracksite of aveyron southern france
Geological Magazine, 2021Co-Authors: Jeandavid Moreau, Jacques Sciau, Georges Gand, Emmanuel FaraAbstract:A recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a doloMudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the Mudflat of the Causses Basin was sporadically affected by large Mud Flows that reworked and redeposited Mudstone intraclasts coming from the erosion of upstream, dry and partially lithified Mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.