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V. V. Mitta - One of the best experts on this subject based on the ideXlab platform.
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Biostratigraphy of the Bajocian–Bathonian boundary beds in the basin of the Bolshoi Zelenchuk River (Northern Caucasus)
Stratigraphy and Geological Correlation, 2017Co-Authors: V. V. Mitta, Anna A. Feodorova, Yu. N. Savelieva, Olga V. ShurekovaAbstract:The study of ammonites from the upper part of the upper Bajocian and lower part of the lower Bathonian in the sections of the basin of the Bolshoi Zelenchuk (Karachay-Cherkessia) allowed the recognition of Beds with Parkinsonia djanelidzei (approximate equivalent of the middle part of the Parkinsonia parkinsoni Chronozone) and Beds with Oraniceras scythicum (lower part of the Zigzagiceras zigzag Chronozone). The taxonomic composition and distribution of foraminifers, ostracodes, dinoflagellate cysts, and miospores were studied in the samples from these deposits (upper part of the upper member of Djangura Formation). The recognized characteristic assemblages of microfauna and palynomorphs allowed ostracode and dinocyst subdivisions to be proposed for the Bajocian–Bathonian boundary beds of the Northern Caucasus for the first time. The most important taxa, including ammonites, foraminifers, ostracodes, and dinocysts, are illustrated.
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biostratigraphy of the bajocian Bathonian boundary beds in the basin of the bolshoi zelenchuk river northern caucasus
Stratigraphy and Geological Correlation, 2017Co-Authors: Anna A. Feodorova, V. V. Mitta, Yu. N. Savelieva, Olga V. ShurekovaAbstract:The study of ammonites from the upper part of the upper Bajocian and lower part of the lower Bathonian in the sections of the basin of the Bolshoi Zelenchuk (Karachay-Cherkessia) allowed the recognition of Beds with Parkinsonia djanelidzei (approximate equivalent of the middle part of the Parkinsonia parkinsoni Chronozone) and Beds with Oraniceras scythicum (lower part of the Zigzagiceras zigzag Chronozone). The taxonomic composition and distribution of foraminifers, ostracodes, dinoflagellate cysts, and miospores were studied in the samples from these deposits (upper part of the upper member of Djangura Formation). The recognized characteristic assemblages of microfauna and palynomorphs allowed ostracode and dinocyst subdivisions to be proposed for the Bajocian–Bathonian boundary beds of the Northern Caucasus for the first time. The most important taxa, including ammonites, foraminifers, ostracodes, and dinocysts, are illustrated.
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biostratigraphy and sedimentary settings of the upper bajocian lower Bathonian in the vicinity of saratov central russia
Neues Jahrbuch Fur Geologie Und Palaontologie-abhandlungen, 2014Co-Authors: V. V. Mitta, V V Kostyleva, O S Dzyuba, Larisa Glinskikh, B N Shurygin, Vladimir Seltzer, Alexey Ivanov, O S UrmanAbstract:This paper presents the results of a detailed study of the Bajocian-Bathonian sections in the “Sokur” Quarry near the city of Saratov and of a borehole drilled in the same quarry. The study of these Bajocian-Bathonian boundary beds, unique for the Boreal-Tethyan ecotone, offers a solution to the much-debated problem of the Middle Jurassic Boreal-Tethyan correlation. The BajocianBathonian boundary beds of this section contain both Peri-Tethyan and Boreal ammonite species, allowing recognition of the Boreal ammonite zones and associated “Boreal” Bathonian zones based on belemnites, bivalves, and foraminifers. This integrated biostratigraphy allows correlation of the Late Bajocian-Early Bathonian boundary interval of the Boreal Jurassic scale with the Submediterranean standard scale.
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Ammonites of the genus Cadoceras (Cardioceratidae) from the uppermost Bathonian-Lowermost Callovian of the northern Caucasus (Ingushetia)
Paleontological Journal, 2011Co-Authors: V. V. MittaAbstract:Based on the study of the ammonite collection assembled by A.S. Sakharov from the Middle Jurassic Armkhi Formation of the Gerchyoch Mountain Pass (northern Ingushetia) and on literature sources, the species composition and stratigraphic position of northern Caucasian Cadoceras are discussed. Early Callovian C. tchegemicum Lominadze, C. tschernyschewi Sokolov, and C. suevicum Callomon et Dietl are identified; the name C. loginovae Lominadze, 2004 is synonymized under C. stupachenkoi Mitta, 1998. The Late Bathonian species are identified as C. sakharovi sp. nov. and C. aff. perrarum Voronetz. The presence of Upper Bathonian sediments is substantiated for the northern Caucasus; the theory of the inversion of the Kepplerites beds is shows to be erroneous.
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The Upper Bajocian-Lower Bathonian boundary section in the outskirts of Saratov: Molluscan characteristics and biostratigraphy
Stratigraphy and Geological Correlation, 2011Co-Authors: V. V. Mitta, Victor Zakharov, I. S. Barskov, V. B. Sel’tser, A. V. IvanovAbstract:The analysis of all available data on the structure of the Bajocian-Bathonian boundary section in the outskirts of Saratov (Sokur quarry) and the taxonomic composition of its ammonites, belemnites, and bivalves revealed a continuous succession of the Pseudocosmoceras michalskii (Upper Bajocian), Oraniceras besnosovi, and Arcticoceras ishmae (Lower Bathonian) zones. In connection with the critique by Meledina et al. (2009), correlation of Bajocian and Bathonian boundary strata of the Central Russia and Northern Siberia is discussed. The inconsistency of Siberian bivalve and belemnite assemblages with Central Russian ammonite zones is explained by heterochronous invasions of different molluscan groups.
Pavel P. Skutschas - One of the best experts on this subject based on the ideXlab platform.
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haramiyidan mammals from the middle jurassic of western siberia russia part 1 shenshouidae and maiopatagium
Journal of Vertebrate Paleontology, 2019Co-Authors: Alexander O Averianov, Pavel P. Skutschas, Thomas Martin, A V Lopatin, Julia A Schultz, Rico Schellhorn, S A Krasnolutskii, Stepan IvantsovAbstract:Three new euharamiyidan taxa are described based on isolated teeth from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk coal mine in Krasnoyarsk Territory, Western Siberia, Russia. ...
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On the Finding of Neosuchians (Neosuchia, Crocodyliformes) in the Middle Jurassic (Bathonian) Deposits of the Moscow Region
Paleontological Journal, 2018Co-Authors: D. I. Pashchenko, Pavel P. Skutschas, Ivan Kuzmin, A. G. Sennikov, M. B. EfimovAbstract:Remains of neosuchian crocodyliforms (isolated teeth, fragment mandibular bone) from the Middle Jurassic (Bathonian) Peski locality in the Moscow Region are described for the first time. The neosuchian from Peski is characterized by well-pronounced ornamentation on the dermal skull bones, and also bicarinate teeth oval in cross section without serration and with triangular conical crowns and fine striation of the enamel. The similarity of Bathonian vertebrate faunas of the Moscow Region, Great Britain, Western Siberia, and Kyrgyzstan is evidence of homogeneity of the vertebrate fauna throughout Laurasia.
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A new crown-group salamander from the Middle Jurassic of Western Siberia, Russia
Palaeobiodiversity and Palaeoenvironments, 2015Co-Authors: Pavel P. SkutschasAbstract:A new crown-group salamander, Kiyatriton krasnolutskii sp. nov., from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk Quarry locality in Western Siberia, Russia, is described on the basis of new material and a dentary fragment previously referred to the undescribed salamander taxon “Berezovsk salamander B” (sensu Skutschas2013). Kiyatriton krasnolutskii sp. nov. differs from K. leshchinskiyi (type species of the genus Kiyatriton) in that the ventrolateral ridges on the atlas are sharper anteriorly, more ventrally oriented and reach the anterior cotylar rims and that the dentary has a relatively taller dental parapet. Kiyatriton krasnolutskii sp. nov. is one of the oldest salamanders in the fossil record. The finding of Kiyatriton krasnolutskii sp. nov. in Berezovsk Quarry is significant for: (1) clarifying that the previously reported “Berezovsk salamander B” is a crown-group salamander of the genus Kiyatriton; (2) extending the stratigraphic range of the genus Kiyatriton backward some 40 million years into the Bathonian, from the previously youngest record in the Aptian–Albian; (3) indicating that K. leshchinskiyi from the Aptian–Albian Shestakovo locality in Western Siberia, Russia, survived as a relic into the Early Cretaceous of present-day Western Siberia; (4) supporting the hypothesis that Bathonian vertebrate faunas of Europe and Western Siberia were homogeneous; and (5) suggesting that all Bathonian crown-group salamanders in Asia could be members of one cryptobranchoid clade and could represent the first radiation of Cryptobranchoidea.
Sixto R. Fernández-lópez - One of the best experts on this subject based on the ideXlab platform.
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The Global Boundary Stratotype Section and Point (GSSP) for Base of the Bathonian Stage (Middle Jurassic), Ravin du Bes Section, SE France
Episodes, 2009Co-Authors: Sixto R. Fernández-lópez, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Nicol Morton, Daniele TiraboschiAbstract:The Bathonian GSSP is defined at the base of limestone bed RB071 in the Ravin du Bes Section, Bas-Auran area, southern Subalpine Chains (France). This section satisfies most of the requirements recommended by the International Commission on Stratigraphy. The exposure extends over 13 m in thickness. No vertical biofacies, ichnofacies or taphofacies changes, stratigraphic gaps or hiatuses have been recorded at the Bajocian-Bathonian transition. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. There is a well-preserved, abundant and diverse fossil record, with key markers (ammonites and nannofossils). The base of Bathonian Stage and Zigzag Zone corresponds to the first occurrence level of Gonolkites convergens Buckman that coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils are present in all beds. The GSSP is below the Tethyan calcareous nannofossil NJT10b/11 zonal boundary (lowest Watznaueria barnesiae) and above the Boreal nannofossil NJ10/11 boundary (lowest Pseudoconus enigma). Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate interpretation of an Early Bathonian deepening half-cycle of second order. The criteria of accessibility, conservation and protection are assured by the "Reserve Naturelle Geologique de Haute Provence". The Cabo Mondego Section (Portugal) is the Bathonian auxiliary section and point (ASSP). The proposal was voted by the Bathonian Working Group in December, 2007, and by the International Subcommission on Jurassic Stratigraphy in March, 2008, approved by the ICS in June 2008, and ratified by the IUGS in July, 2008.
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Formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France)
Swiss Journal of Geosciences, 2009Co-Authors: Sixto R. Fernández-lópez, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Daniele TiraboschiAbstract:The Bathonian Global Stratotype Section and Point (GSSP) is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bes Section (43° 57′ 38′′ N, 6° 18′ 55′′ E), Bas-Auran area, “Alpes de Haute Provence” French department. The Ravin du Bes Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy: 1) The exposure extends over 13 m in thickness. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, condensation, stratigraphic gaps or hiatuses have been recorded. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation. The base of the Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman, which coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. 4) The criteria of accessibility, conservation and protection are assured by the “Reserve Naturelle Geologique de Haute Provence”. The Cabo Mondego Section (Portugal) is suggested as the Bathonian auxiliary section and point (ASSP) within this GSSP proposal.
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Candidate sections for the GSSP of the base of the Bathonian Stage (Middle Jurassic)
2009Co-Authors: Sixto R. Fernández-lópezAbstract:In accordance with the recommendations of the International Commission on Stratigraphy (ICS), the leading candidate for the Global Boundary Stratotype Section and Point (GSSP) of the base of the Bathonian Stage is located in the Ravin du Bes (Bas Auran area, SE France). This section was formally proposed as candidate nineteen years ago. A second potential candidate section is located in the Cabo Mondego area (Portugal). This Portuguese section, however, has not been formally proposed as a candidate for the Bathonian basal boundary stratotype. The formal selection and proposal of a GSSP for the Bathonian Stage is the responsibility of the Bathonian Working Group (BtWG) and is expected by September 2007. In accordance with the procedures to ratify GSSPs, a formal ballot on the selection and proposal of a GSSP for the Bathonian Stage, by post or email, by all members of the BtWG is the responsibility of the convenor and the International Subcommission on Jurassic Stratigraphy Executive, and will be carried out within this time scale.
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Ammonoid succession at the Bajocian-Bathonian transition in the Bas Auran area, Digne district, South-East France.
Rivista Italiana Di Paleontologia E Stratigrafia, 2008Co-Authors: Giulio Pavia, Sixto R. Fernández-lópez, Charles MangoldAbstract:The uppermost Bajocian to lowermost Bathonian ammonoid succession has been studied in the Bas Auran area in view of choosing one of its sections as the Global Stratotype Section and Point (G.S.S.P.) of the Bathonian Stage. The Bas Auran ammonite assemblages display exceptional values of record quality. The stratigraphic distribution of 629 specimens referred to 63 species and 35 genera, collected during the last forty years from three sections (Ravin du Bes, Ravin d'Auran, Ravin des Robines), is plotted and analyzed, bed by bed. Over 85 stratigraphic levels, through 9 m in thickness, have been studied at the top of the "Marno-calcaires a Cancellophycus" formation, ranging from the latest Bajocian (Parkinsoni Zone, Bomfordi Subzone) to the earliest Bathonian (Zigzag Zone, Convergens Subzone) and the base of the Macrescens Subzone. Ammonoid assemblages are composed of Northwest European and Mediterranean elements, associated with Sub-Mediterranean ones, allowing chronocorrelation between the Northwest European Convergens Subzone and the Sub-Mediterranean Parvum Subzone. The basal boundary of the Zigzag Zone and of the Bathonian Stage is placed at the base of Sturani's bed 23 in the Ravin du Bes section and is identified by the first occurrence of Gonolkites convergens, and coincides with the loest occurrence of Morphoceras parvum. Features of the ammonoid succession indicate relatively homogeneous and good record quality, gradual biostratigraphic change and high degree of taxonomic similarity between the Bomfordi and Convergens subzones. Palaeontological criteria also indicate relatively high values of palaeontological and stratigraphic completeness at the base of levels RB070-RB071 (= level 23 in Sturani 1967) which corresponds to the Bajocian/Bathonian boundary. The Ravin du Bes Section, with forty-six successive ammonoid fossil-assemblages of the Convergens Subzone belonging to three biohorizons through five metres of thickness, shows maximum values of biostratigraphic and biochronostratigraphic completeness, being one of the most complete in the world. Therefore, the Ravin du Bes Section should be chosen as the Global Stratotype Section and Point for the base of the Bathonian Stage. Two biostratigraphic logs summarize the ammonite content from the uppermost Bomfordi to basal Macrescens subzones. Three plates illustrate the most characteristic ammonoid taxa at the Bajocian-Bathonian passage in the Bas Auran succession.
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Ammonoid taphonomy, palaeoenvironments and sequence stratigraphy at the Bajocian/Bathonian boundary on the Bas Auran area (Subalpine Basin, south‐eastern France)
Lethaia, 2007Co-Authors: Sixto R. Fernández-lópezAbstract:Bas Auran, in south-eastern France, is the candidate area for Global Boundary Stratotype Section and Point (GSSP) of the base of the Bathonian Stage (Middle Jurassic). In the Bas Auran area, upper Bajocian and lower Bathonian deposits are made up of limestone beds alternating with marls that correspond to the ‘Marno-calcaires a Cancellophycus’, below the ‘Terres Noires’ Formation. Taphonomic analyses of the successive ammonoid fossil assemblages provide new and complementary data for biostratigraphic completeness, palaeoenvironmental setting and sequence stratigraphy. Lithologic differentiation between limestone and marl intervals resulted from alternating episodes of carbonate input and starvation. Both lithologic phases may contain evidence for sedimentary and taphonomic reworking, associated with scours, that reflects low rates of sedimentation and stratigraphic condensation. Three successive types of elementary cycles resulted from increasing rates of stratigraphic condensation, sedimentary condensation and substrate stabilization during early Bathonian. The occurrence of reelaborated ammonoids (i.e. exhumed and displaced before their final burial) implies that tractive current flows or winnowing affected the burial of concretionary internal moulds. In the lower Bathonian strata, the dominance of homogeneous concretionary internal moulds of phragmocones, completely filled with sediment, is indicative of low rates of sedimentation and sediment accumulation, respectively associated with low degrees of stratigraphic and sedimentary condensation. However, at the Bajocian/ Bathonian transition, hemipelagic, bed-scale limestone–marl alternations show a maximum value of biostratigraphic completeness and there is no evidence for taphonomic condensation in the ammonoid fossil assemblages. Taphonomic analyses of the successive ammonoid fossil assemblages and taphofacies confirm the development of a deepening phase associated with sedimentary starvation, which characterizes the last episode within the deepening half-cycle of third and second order cycles, in the Bas Auran area of French Subalpine Basin during early Bathonian.
Charles Mangold - One of the best experts on this subject based on the ideXlab platform.
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The Global Boundary Stratotype Section and Point (GSSP) for Base of the Bathonian Stage (Middle Jurassic), Ravin du Bes Section, SE France
Episodes, 2009Co-Authors: Sixto R. Fernández-lópez, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Nicol Morton, Daniele TiraboschiAbstract:The Bathonian GSSP is defined at the base of limestone bed RB071 in the Ravin du Bes Section, Bas-Auran area, southern Subalpine Chains (France). This section satisfies most of the requirements recommended by the International Commission on Stratigraphy. The exposure extends over 13 m in thickness. No vertical biofacies, ichnofacies or taphofacies changes, stratigraphic gaps or hiatuses have been recorded at the Bajocian-Bathonian transition. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. There is a well-preserved, abundant and diverse fossil record, with key markers (ammonites and nannofossils). The base of Bathonian Stage and Zigzag Zone corresponds to the first occurrence level of Gonolkites convergens Buckman that coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils are present in all beds. The GSSP is below the Tethyan calcareous nannofossil NJT10b/11 zonal boundary (lowest Watznaueria barnesiae) and above the Boreal nannofossil NJ10/11 boundary (lowest Pseudoconus enigma). Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate interpretation of an Early Bathonian deepening half-cycle of second order. The criteria of accessibility, conservation and protection are assured by the "Reserve Naturelle Geologique de Haute Provence". The Cabo Mondego Section (Portugal) is the Bathonian auxiliary section and point (ASSP). The proposal was voted by the Bathonian Working Group in December, 2007, and by the International Subcommission on Jurassic Stratigraphy in March, 2008, approved by the ICS in June 2008, and ratified by the IUGS in July, 2008.
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Formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France)
Swiss Journal of Geosciences, 2009Co-Authors: Sixto R. Fernández-lópez, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Daniele TiraboschiAbstract:The Bathonian Global Stratotype Section and Point (GSSP) is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bes Section (43° 57′ 38′′ N, 6° 18′ 55′′ E), Bas-Auran area, “Alpes de Haute Provence” French department. The Ravin du Bes Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy: 1) The exposure extends over 13 m in thickness. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, condensation, stratigraphic gaps or hiatuses have been recorded. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation. The base of the Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman, which coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. 4) The criteria of accessibility, conservation and protection are assured by the “Reserve Naturelle Geologique de Haute Provence”. The Cabo Mondego Section (Portugal) is suggested as the Bathonian auxiliary section and point (ASSP) within this GSSP proposal.
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Ammonoid succession at the Bajocian-Bathonian transition in the Bas Auran area, Digne district, South-East France.
Rivista Italiana Di Paleontologia E Stratigrafia, 2008Co-Authors: Giulio Pavia, Sixto R. Fernández-lópez, Charles MangoldAbstract:The uppermost Bajocian to lowermost Bathonian ammonoid succession has been studied in the Bas Auran area in view of choosing one of its sections as the Global Stratotype Section and Point (G.S.S.P.) of the Bathonian Stage. The Bas Auran ammonite assemblages display exceptional values of record quality. The stratigraphic distribution of 629 specimens referred to 63 species and 35 genera, collected during the last forty years from three sections (Ravin du Bes, Ravin d'Auran, Ravin des Robines), is plotted and analyzed, bed by bed. Over 85 stratigraphic levels, through 9 m in thickness, have been studied at the top of the "Marno-calcaires a Cancellophycus" formation, ranging from the latest Bajocian (Parkinsoni Zone, Bomfordi Subzone) to the earliest Bathonian (Zigzag Zone, Convergens Subzone) and the base of the Macrescens Subzone. Ammonoid assemblages are composed of Northwest European and Mediterranean elements, associated with Sub-Mediterranean ones, allowing chronocorrelation between the Northwest European Convergens Subzone and the Sub-Mediterranean Parvum Subzone. The basal boundary of the Zigzag Zone and of the Bathonian Stage is placed at the base of Sturani's bed 23 in the Ravin du Bes section and is identified by the first occurrence of Gonolkites convergens, and coincides with the loest occurrence of Morphoceras parvum. Features of the ammonoid succession indicate relatively homogeneous and good record quality, gradual biostratigraphic change and high degree of taxonomic similarity between the Bomfordi and Convergens subzones. Palaeontological criteria also indicate relatively high values of palaeontological and stratigraphic completeness at the base of levels RB070-RB071 (= level 23 in Sturani 1967) which corresponds to the Bajocian/Bathonian boundary. The Ravin du Bes Section, with forty-six successive ammonoid fossil-assemblages of the Convergens Subzone belonging to three biohorizons through five metres of thickness, shows maximum values of biostratigraphic and biochronostratigraphic completeness, being one of the most complete in the world. Therefore, the Ravin du Bes Section should be chosen as the Global Stratotype Section and Point for the base of the Bathonian Stage. Two biostratigraphic logs summarize the ammonite content from the uppermost Bomfordi to basal Macrescens subzones. Three plates illustrate the most characteristic ammonoid taxa at the Bajocian-Bathonian passage in the Bas Auran succession.
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The base of the Zigzag Zone in the Ravin du Bès Section (Bas-Auran, Subalpine Basin,SE France) as the GSSP for the base of the Bathonian Stage
2008Co-Authors: Sixto Rafael Fernández López, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Nicol Morton, Daniele TiraboschiAbstract:The Global Boundary Stratotype Section and Point (GSSP) for the base of the Bathonian Stage is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bes Section (43o57’38’’N, 6o18’55’’E), Bas-Auran area, in the Chaudon-Norante commune, around 25 km at the South-Southeast of Digne-les-Bains, in the “Alpes de Haute Provence” French department. The Ravin du Bes Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy (ICS): 1) The exposure extends over 13 m in thickness, comprising more than five metres of fossiliferous levels below and above the boundary. The Bathonian basal bed corresponds to the “Marno-calcaires a Cancellophycus”, is located 7.8 m below the “Terres Noires” Formation and forms part of a transgressive-facies cycle. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, stratigraphic gaps or hiatuses have been recorded. There is no evidence of taphonomic condensation (i.e. mixture of fossils of different age or different chronostratigraphic units). Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints in the Bas-Auran area. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation of the uppermost Bajocian and Lower Bathonian. The boundary can be characterized by both primary and secondary (auxiliary) biostratigraphic markers. The section appears to be suitable for biostratigraphic study of microfossils, such as foraminifera, but as yet there are no published studies. The base of Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman and the renewal of parkinsonids. This level coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds, enabling documentation of the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate interpretation of an Early Bathonian deepening half-cycle of second order. No data are currently available for strontium isotope (87Sr/86Sr ratio), oxygen isotope (δ18O) or carbon isotope (δ13C) chemostratigraphy. Bajocian and Bathonian deposits have been remagnetized with a steady normal polarity. Volcanogenic deposits suitable for direct radio-isotope dating are not known in the section. 4) The criteria of accessibility, conservation and protection are assured by the “Reserve Naturelle Geologique de Haute Provence”, protected under national law as recognised by UNESCO. The Cabo Mondego Section (Portugal), which provides complementary data on the ammonite succession in the Sub-Mediterranean Parvum Subzone and its chronocorrelation with the Northwest European Convergens Subzone, is suggested as the Bathonian auxiliary section and point (ASP) within this GSSP proposal.
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Formal proposal for the Global Boundary Stratotype Section and Point (GSSP) of the Bathonian Stage, at the base of the Zigzag Zone in the Ravin du Bès Section (Bas-Auran, Subalpine Basin, SE France).
2007Co-Authors: Sixto Rafael Fernández López, Giulio Pavia, Elisabetta Erba, Myett Guiomar, Maria Helena Henriques, Roberto Lanza, Charles Mangold, Davide Olivero, Daniele TiraboschiAbstract:The Global Boundary Stratotype Section and Point (GSSP) for the base of the Bathonian Stage is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bes Section (43o57’38’’N, 6o18’55’’E), Bas-Auran area, in the Chaudon-Norante commune, around 25 km at the South-Southeast of Digne-les-Bains, in the “Alpes de Haute Provence” French department. The Ravin du Bes Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy (ICS): 1) The exposure extends over 13 m in thickness, comprising more than five metres of fossiliferous levels below and above the boundary. The Bathonian basal bed corresponds to the “Marno-calcaires a Cancellophycus”, is located 7.8 m below the “Terres Noires” Formation and forms part of a transgressive-facies cycle. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, stratigraphic gaps or hiatuses have been recorded. There is no evidence of taphonomic condensation (i.e. mixture of fossils of different age or different chronostratigraphic units). Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints in the Bas-Auran area. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation of the uppermost Bajocian and Lower Bathonian. The boundary can be characterized by both primary and secondary (auxiliary) biostratigraphic markers. The section appears to be suitable for biostratigraphic study of microfossils, such as foraminifera, but as yet there are no published studies. The base of Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the renewal of parkinsonids and the first occurrence level of Gonolkites convergens Buckman. This level coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. No data are currently available for strontium isotope (87Sr/86Sr ratio), oxygen isotope (δ18O) or carbon isotope (δ13C) chemostratigraphy. Bajocian and Bathonian deposits have been remagnetized with a steady normal polarity. Volcanogenic deposits suitable for direct radio-isotope dating are not known in the section. 4) The criteria of accessibility, conservation and protection are assured by the “Reserve Naturelle Geologique de Haute Provence”, protected under national law as recognised by UNESCO. The Cabo Mondego Section (Portugal), which provides complementary data of the ammonite succession at the Sub-Mediterranean Parvum Subzone and its chronocorrelation with the Northwest European Convergens Subzone, is suggested as the Bathonian auxiliary section and point (ASP) within this GSSP proposal.
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haramiyidan mammals from the middle jurassic of western siberia russia part 1 shenshouidae and maiopatagium
Journal of Vertebrate Paleontology, 2019Co-Authors: Alexander O Averianov, Pavel P. Skutschas, Thomas Martin, A V Lopatin, Julia A Schultz, Rico Schellhorn, S A Krasnolutskii, Stepan IvantsovAbstract:Three new euharamiyidan taxa are described based on isolated teeth from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk coal mine in Krasnoyarsk Territory, Western Siberia, Russia. ...
