The Experts below are selected from a list of 18180 Experts worldwide ranked by ideXlab platform
Petr Skupien - One of the best experts on this subject based on the ideXlab platform.
-
The Jurassic/Cretaceous Boundary and high resolution biostratigraphy of the pelagic sequences of the kurovice section (Outer Western Carpathians, the northern Tethyan margin)
Geologica Carpathica, 2019Co-Authors: Andrea Svobodová, Daniela Reháková, Petr Skupien, Marcela Svobodová, Lilian Švábenická, Tiiu Elbra, Petr SchnablAbstract:Abstract Microfacies and high resolution studies at the Kurovice quarry (Czech Republic, Outer Western Carpathians) on calpionellids, calcareous and non-calcareous dinoflagellate cysts, sporomorphs and calcareous nannofossils, aligned with paleomagnetism, allow construction of a detailed stratigraphy and paleoenvironmental interpretation across the Jurassic/Cretaceous (J/K) Boundary. The Kurovice section consists of allodapic and micrite limestones and marlstones. Identified standard microfacies types SMF 2, SMF 3 and SMF 4 indicate that sediments were deposited on a deep shelf margin (FZ 3), with a change, later, into distal basin conditions and sediments (FZ 1). The sequence spans a stratigraphic range from the Early Tithonian calcareous dinoflagellate Malmica Zone, nannoplankton zone NJT 15 and magnetozone M 21r to the late Early Berriasian calpionellid Elliptica Subzone of the Calpionella Zone, nannoplankton NK-1 Zone and M 17r magnetozone. The J/K Boundary is marked by a quantitative increase of small forms of Calpionella alpina, the base of the Alpina Subzone (that corresponds to NJT 17b and M 19n.2n) and by the rare occurrence of Nannoconus wintereri. Palynomorphs include Early Berriasian terrestrial elements — non-calcareous dinoflagellate cysts Achomosphaera neptunii, Prolixosphaeridium sp. A and Tehamadinium evittii. The depositional area for Kurovice was situated at the margin of the NW Tethys. The influence of cold waters from northern latitudes and potential upwellings is highlighted by: 1) the high proportion of radiolarians and sponge spicules, 2) rare calpionellids represented mostly by hyaline forms, 3) the absence of microgranular calpionellids — chitinoidellids, 4) the small percentage of the genera Nannoconus, Polycostella and Conusphaera in nannofossil assemblages, as compared to other sites in Tethys, 5) scarce Nannoconus compressus, which has otherwise been mentioned from the Atlantic area.
-
dinoflagellates and calpionellids of the jurassic cretaceous Boundary outer western carpathians czech republic
Cretaceous Research, 2019Co-Authors: Petr Skupien, Pavlina DoupovcovaAbstract:Abstract A palynological analysis and study of calpionellids and calcareous dinoflagellate cysts across the Jurassic–Cretaceous (J/K) Boundary succession in the Outer Western Carpathians, Bruzovice section is presented. It is a one of few sections of the Tethyan Realm suitable for the palynological study. The lower part of the section is formed by anoxic deposits consisting of dark grey calcareous claystones. The upper part of the profile is represented by flysch-like alternation of grey limestones, spotted claystones and marlstones. The section spans the stratigraphic range from the upper Tithonian, Cadosina semiradiata calcareous dinoflagellate Zone to the lower Berriasian, calpionellid Calpionella elliptica Subzone. The J/K Boundary is marked by a high abundance of small forms of Calpionella alpina . The Tithonian–Berriasian succession of non–calcareous dinoflagellates is as follows: the base of the section is correlated with the dinocyst Semiradiata Zone along with the presence of Glossodinium dimorphum. The first occurrence (FO) of Amphorula metaelliptica and the last occurrence (LO) of Prolixosphaeridium anasillum are recorded in the Cadosina semiradiata Zone followed by the Cadosina tenuis – Colomisphaera fortis Zone. An aboudance of the spherical C. alpina indicates the onset of the Calpionella Zone and the Calpionella alpina Subzone at the base of the Berriasian Stage. The FO of Diacanthum hollisteri is situated in the lower part of the Calpionella alpina Subzone. The FO of Dichadogonyaulax bensonii coincides approximately with the base of the calpionellid Remaniella ferasini Subzone, and the FO´s of Muderongia longicorna, M. tabulata and Spiniferites cf. ramosus were found in the upper part of the calpionellid Remaniella ferasini Subzone. The FO of Achomosphaera neptunii was found in the lower part of the Calpionella elliptica Subzone. The work is a contribution to the ICS Berriasian Working Group.
Pavlina Doupovcova - One of the best experts on this subject based on the ideXlab platform.
-
dinoflagellates and calpionellids of the jurassic cretaceous Boundary outer western carpathians czech republic
Cretaceous Research, 2019Co-Authors: Petr Skupien, Pavlina DoupovcovaAbstract:Abstract A palynological analysis and study of calpionellids and calcareous dinoflagellate cysts across the Jurassic–Cretaceous (J/K) Boundary succession in the Outer Western Carpathians, Bruzovice section is presented. It is a one of few sections of the Tethyan Realm suitable for the palynological study. The lower part of the section is formed by anoxic deposits consisting of dark grey calcareous claystones. The upper part of the profile is represented by flysch-like alternation of grey limestones, spotted claystones and marlstones. The section spans the stratigraphic range from the upper Tithonian, Cadosina semiradiata calcareous dinoflagellate Zone to the lower Berriasian, calpionellid Calpionella elliptica Subzone. The J/K Boundary is marked by a high abundance of small forms of Calpionella alpina . The Tithonian–Berriasian succession of non–calcareous dinoflagellates is as follows: the base of the section is correlated with the dinocyst Semiradiata Zone along with the presence of Glossodinium dimorphum. The first occurrence (FO) of Amphorula metaelliptica and the last occurrence (LO) of Prolixosphaeridium anasillum are recorded in the Cadosina semiradiata Zone followed by the Cadosina tenuis – Colomisphaera fortis Zone. An aboudance of the spherical C. alpina indicates the onset of the Calpionella Zone and the Calpionella alpina Subzone at the base of the Berriasian Stage. The FO of Diacanthum hollisteri is situated in the lower part of the Calpionella alpina Subzone. The FO of Dichadogonyaulax bensonii coincides approximately with the base of the calpionellid Remaniella ferasini Subzone, and the FO´s of Muderongia longicorna, M. tabulata and Spiniferites cf. ramosus were found in the upper part of the calpionellid Remaniella ferasini Subzone. The FO of Achomosphaera neptunii was found in the lower part of the Calpionella elliptica Subzone. The work is a contribution to the ICS Berriasian Working Group.
Victor A Ramos - One of the best experts on this subject based on the ideXlab platform.
-
high precision u pb ages in the early tithonian to early berriasian and implications for the numerical age of the jurassic cretaceous Boundary
Solid Earth, 2019Co-Authors: Luis Lena, Rafael Lopezmartinez, Marina Lescano, Veronica V Vennari, Maximiliano Naipauer, Andrea Concheyro, Elias Samankassou, Márcio Martins Pimentel, Beatriz Aguireurreta, Victor A RamosAbstract:Abstract. The numerical age of the Jurassic–Cretaceous Boundary has been controversial and difficult to determine. In this study, we present high-precision U–Pb geochronological data around the Jurassic–Cretaceous Boundary in two distinct sections from different sedimentary basins: the Las Loicas, Neuquen Basin, Argentina, and the Mazatepec, Sierra Madre Oriental, Mexico. These two sections contain primary and secondary fossiliferous markers for the Boundary as well as interbedded volcanic ash horizons, allowing researchers to obtain new radioisotopic dates in the late Tithonian and early Berriasian. We also present the first age determinations in the early Tithonian and tentatively propose a minimum duration for the stage as a cross-check for our ages in the early Berriasian. Given our radioisotopic ages in the early Tithonian to early Berriasian, we discuss implications for the numerical age of the Boundary.
-
reply to comments on tethyan calpionellids in the neuquen basin argentine andes their significance in defining the jurassic cretaceous Boundary and pathways for tethyan eastern pacific connections by kietzmann iglesia llanos
Journal of South American Earth Sciences, 2017Co-Authors: Rafael Lopezmartinez, Beatriz Aguirreurreta, Marina Lescano, Veronica V Vennari, Andrea Concheyro, Victor A RamosAbstract:Abstract The comments by Kietzmann & Iglesia Llanos (Comment on “Tethyan calpionellids in the Neuquen Basin (Argentine Andes), their significance in defining the Jurassic/Cretaceous Boundary and pathways for Tethyan-Eastern Pacific connections” by R. Lopez-Martinez, B. Aguirre-Urreta, M. Lescano, A. Concheyro, V. Vennari and V. Ramos) on our paper published in the Journal of South American Earth Sciences 78 (2017): 116-125, provide a worthy opportunity to further clarify our observations and interpretations regarding the importance of precise biostratigraphic studies in the definition of the Jurassic/Cretaceous Boundary in the Argentine Andes. These include the calpionellids as primary markers, the classic and widespread nannofossils bioevents as secondary markers, together with a detailed ammonite zonation.
-
tethyan calpionellids in the neuquen basin argentine andes their significance in defining the jurassic cretaceous Boundary and pathways for tethyan eastern pacific connections
Journal of South American Earth Sciences, 2017Co-Authors: Rafael Lopezmartinez, Beatriz Aguirreurreta, Marina Lescano, Veronica V Vennari, Andrea Concheyro, Victor A RamosAbstract:Abstract The study of calpionellid distribution in the well-documented Las Loicas section of the Vaca Muerta Formation in the Neuquen Basin, Argentine Andes, allows the recognition of the upper part of the Crassicollaria Zone and the lower part of Calpionella Zone across the Jurassic/Cretaceous Boundary. The Crassicollaria Zone, Colomi Subzone (Upper Tithonian) is composed of Calpionella alpina Lorenz, Crassicollaria colomi Doben, Crassicollaria parvula Remane, Crassicollaria massutiniana (Colom), Crassicollaria brevis Remane, Tintinnopsella remanei (Borza) and Tintinnopsella carpathica (Murgeanu and Filipescu). The Calpionella Zone, Alpina Subzone (Lower Berriasian) is indicated by the explosion of the small and globular form of Calpionella alpina dominating over very scarce Crassicollaria massutiniana. The FAD of Nannoconus wintereri can be clearly correlated with the upper part of Crassicollaria Zone and the FAD of Nannoconus kamptneri minor with the Calpionella Zone. Additional studies are necessary to establish a more detailed calpionellid biozonation and its correlation with other fossil groups. The present work confirms similar calpionellid bioevents in westernmost Tethys (Cuba and Mexico) and the Andean region, strengthening the Paleo-Pacific-Tethyan connections through the Hispanic Corridor already known from other fossil groups.
William A P Wimbledon - One of the best experts on this subject based on the ideXlab platform.
-
palaeo and rock magnetic investigations across jurassic cretaceous Boundary at st bertrand s spring drome france applications to magnetostratigraphy
Studia Geophysica Et Geodaetica, 2018Co-Authors: Tiiu Elbra, Daniela Reháková, Andrea Svobodová, Petr Schnabl, Camille Frau, Jacek Grabowski, Petr Pruner, Kristýna Cižkova, Simon Kdýr, William A P WimbledonAbstract:Palaeo- and rock-magnetic investigations of the St Bertrand’s Spring (Le Ravin de Font de St Bertrand) locality in France were carried out in order to contribute to, and improve, the stratigraphy of the Jurassic-Cretaceous Boundary interval. Magnetic susceptibility shows slightly diamagnetic behaviour in the lowermost part of the profile and an increase (paramagnetic) towards its middle and upper parts. Rock-magnetic measurements throughout the section show magnetite as the main magnetic fraction, together with traces of hematite. Additionally, thermal demagnetization indicates the presence of goethite. Our magnetostratigraphy indicates three normal/reversed polarity sequences; possibly encompassing the magnetozones M19r to the M17n. This suggests that the St Bertrand section straddles the Tithonian/Berriasian Boundary and reaches the middle Berriasian sensu lato.
-
systematic palaeontology of the perisphinctoidea in the jurassic cretaceous Boundary interval at le chouet drome france and its implications for biostratigraphy
Acta Geologica Polonica, 2016Co-Authors: Camille Frau, William A P Wimbledon, Luc G Bulot, Christina IfrimAbstract:This study describes ammonite taxa of the Perisphinctoidea in the Jurassic/Cretaceous Boundary interval at Le Chouet (Drome, France). Emphasis is placed on new and poorly known Himalayitidae, Neocomitidae and Olcostephanidae from the lower part of the Jacobi Zone auctorum. Significant results relate the introduction of Lopeziceras gen. nov., grouping himalayitid-like forms with two rows of tubercles, and Praedalmasiceras gen. nov., grouping the early Berriasian Dalmasiceras taxa. Study of the ontogenetic sequences of both genera show that they were derived from late Tithonian Himalayitidae. This supports the distinction between the subfamilies Himalayitinae and Dalmasiceratidae subfam. nov. Content, variation, dimorphism and vertical range of the Neocomitidae Berriasella , Pseudoneocomites , Elenaella and Delphinella are discussed. A conservative use of the Olcostephanidae Proniceras is followed herein.
-
inter regional correlation of jurassic cretaceous Boundary strata based on the tithonian valanginian dinoflagellate cyst biostratigraphy of the volga basin western russia
Review of Palaeobotany and Palynology, 2011Co-Authors: Ian C Harding, James B. Riding, Giles A Smith, William A P WimbledonAbstract:Abstract Correlation of Jurassic/Cretaceous Boundary successions in the Boreal Realm based on ammonite biostratigraphy is problematical due to faunal provincialism. This paper investigates the marine palynology of the Tithonian to Valanginian strata at Gorodishche and Kashpir in western Russia, documenting the ranges of > 100 dinoflagellate cyst species used to compile a detailed Tithonian-Valanginian palynostratigraphy for the Volga Basin. Datums of key taxa are used to define ages for unreliably dated strata in the Russian successions by comparison with ranges calibrated to ammonite zones in Boreal northwest Europe. The appearance of Gochteodinia villosa indicates a correlation between the bases of the Late Tithonian Epivirgatites nikitini (ammonite) Zone of the Volga Basin and the Galbanites kerberus Zone of northwest Europe. A dinoflagellate cyst interval zonation, comprising five zones and seven subzones is defined for the Volga Basin. There are notable differences between Tithonian and Berriasian dinoflagellate cyst floras in the Volga Basin and northwest Europe, but Valanginian dinoflagellate cyst assemblages throughout the Northern Hemisphere demonstrate a much more cosmopolitan composition.
-
the jurassic cretaceous Boundary an age old correlative enigma
Episodes, 2008Co-Authors: William A P WimbledonAbstract:The Jurassic-Cretaceous Boundary interval has been problematic since the start of stratigraphic study. This is reflected in different stage names being employed in Boreal and Tethyan realms below and above the putative Boundary. Despite attempts at homogenisation where stage terminology is concerned, correlative precision over long distances at or close to a Boundary has not yet been achieved. But the new Berriasian/ J-K Boundary working-group of the Cretaceous Subcommission is now attempting to remedy this situation.
Atsushi Matsuoka - One of the best experts on this subject based on the ideXlab platform.
-
radiolarian occurrences from the jurassic cretaceous transition beds in the maiolica formation of the bosso valley section northern apennines central italy
Cretaceous Research, 2020Co-Authors: Atsushi Matsuoka, Marco Chiari, Angela BertinelliAbstract:Abstract The Global Boundary Stratotype Section and Point (GSSP) of the Jurassic–Cretaceous Boundary (JKB) is the last among the GSSPs in the Phanerozoic to be chosen. The Berriasian Working Group of the International Subcommission on Cretaceous Stratigraphy decided in 2016 to use the base of the Calpionella alpina Subzone as the primary marker for the formal definition of the JKB. This definition is satisfactorily applicable for near continent, shallow offshore deposits within the Western Tethys, North Atlantic and central-south America. Unfortunately, the primary marker taxon cannot be found in the Pacific and circum-Pacific regions since the distribution of calpionellids is limited to the Western Tethys and neighboring regions. Radiolarians are good candidates for defining the JKB, because they are widespread and can be found both in shallow and deep pelagic sedimentary facies worldwide. We carried out detailed field observations and careful sample collections in a 5-m thick interval around the JKB in the Bosso Valley section (Northern Apennines), which is one of potential candidates for GSSP of the JKB. The Maiolica Formation, which includes the JKB, is characterized by white to light gray, well-bedded micritic limestones with abundant light gray to black chert layers and nodules. In this study, after selection of samples acid-etched in the field, we observed the etched surface with a scanning electron microscope in the laboratory. Our detailed observations revealed that both micritic limestone and chert generally contain abundant radiolarian tests. Most of them in limestones are replaced by calcite, so that it is impossible to isolate radiolarian tests from rock samples with acid treatment. On the other hand, radiolarian tests within chert layers or nodules are too recrystallized to preserve their original surface ornamentation. The best preserved radiolarian tests are included in micritic limestone near chert layer or nodules. Careful and systematic sampling enabled us to get enough material to establish phylogenetic analysis on radiolarians.
-
radiolarian phylogeny around the jurassic cretaceous Boundary and radiolarian occurrences in the bosso valley section central italy
JK2018, 2018Co-Authors: Atsushi Matsuoka, Peter Baumgartner, Luis Odogherty, Spela Gorican, Marco Chiari, Angela BertinelliAbstract:The Global Boundary Stratotype Section and Point (GSSP) of the Jurassic–Cretaceous Boundary (JKB) is the last among the GSSPs in the Phanerozoic. It is defined as the base of the Berriasian Stage. The formal definition was decided in 2016 to use the base of the Calpionella alpin a Subzone as the primary marker by the Berriasian Working Group in the International Subcommission on Cretaceous Stratigraphy. The definition is satisfactorily applicable for shallow marine deposits within the western Tethys, north Atlantic and central-south America. Unfortunately, the primary marker taxon cannot be found in the Pacific and circum-Pacific regions since the distribution of Calpionellids is limited to the western Tethys, north Atlantic and central-south America. To determine the base of the Berriasian outside of these regions, alternative markers are needed. Radiolarians are good candidates for defining the JKB because they are wide spread and can be found both shallow and deep sedimentary facies. Pelagic sequences across the JKB have been reported in ODP/IODP sites in the western Pacific and land sections in Japan, the Philippines, southern Tibet, Iran and others. Evolutionary lineages of several radiolarian taxa across the JKB are reviewed and suitable bioevents, which are approximate to the JKB, are presented. These lineages include the radiolarian genera: Alievium, Archaeodictyomitra, Cinguloturris, Complexapora, Crococapsa, Doliocapsa, Emiluvia, Eucyrtidiellum, Hemicryptocapsa, Hsuum, Loopus, Mirifusus, Mesovallupus, Neorelumbra, Pantanellium, Protovall u pus, Protunuma, Pseudodictyomitra, Ristola, Spinosicapsa , Tethysetta, Thanarla ， Vallupus ， Xitus , Zhamoidellum . Among them the Loopus – Pseudodictyomitra lineage and the Protovallupus – Mesovallupus – Vallupus lineage can be the most important phylogeny for defining the JKB. As discussed by Gorican et al. (2018), the evolutionary first appearance datums (FADs) within firmly recognized lineages are extremely valuable. The Loopus – Pseudodictyomitra lineage is more advantageous than the Protovallupus – Mesovallupus – Vallupus lineage because the former has a much wider paleobiogeographic distribution than the latter. Applying to the so far established radiolarian zones, the JKB lies within the Unitary Association Zone 13 of Baumgartner et al. (1995) and within the Pseudodictyomitra carpatica Zone of Matsuoka (1995). The base of the Pseudodictyomitra carpatica Zone is defined by the evolutionary FAD of Pseudodictyomitra carpatica . Detailed morphological analysis of Loopus and Pseudodictyomitra species is presented and the relationship between the JKB and speciation within the lineage is discussed. The Bosso Valley section in Umbria–Marche, central Italy, is one of potential candidates for GSSP of the JKB. The Maiolica Formation, which crosses the JKB, is characterized by whitish, beige to gray colored, well-bedded micritic limestones with abundant black to gray chert layers and nodules. Calpionellid stratigraphy and magnetostratigraphy have been studied sufficiently in the section (Housa et al. , 2004). The base of the Calpionella alpina Subzone, i.e. , the JKB, is placed between Beds 77 and 78 (Housa et al. , 2004). We carried out detailed field observations and careful sample collections in a 4-m interval across the JKB. Acid-etched examination of rock samples revealed that well-preserved radiolarians are recognized inside the lime part near the chert layers or nodules. Three samples of micritic limestone below the JKB and two samples above the JKB yield moderatly-preserved radiolarians. The result of radiolarian faunal analysis in the Bosso Valley section is presented.
-
catalogue of mesozoic radiolarian genera part 2 jurassic cretaceous
Geodiversitas, 2009Co-Authors: Luis Odogherty, Peter Baumgartner, Elizabeth S Carter, Paulian Dumitrica, Spela Goriccan, Patrick De Wever, Alexandre N Bandini, Atsushi MatsuokaAbstract:ABSTRACT The catalogue of Mesozoic radiolarian genera is a revision of all described genera with re-illustration of their type species. This project was organized under the auspices of the International Association of Radiolarian Paleontologists (Inter-Rad), and was carried out by the Mesozoic Working Group. This is the second of two contributions, this one devoted to the Jurassic-Cretaceous period. It contains 581 genera with re-illustration of their type species. This part shares 30 genera in common with the Triassic catalogue, most of which arose in the Carnian, Norian and Rhaetian. The sharp difference manifested between the Triassic fauna and the Jurassic-Cretaceous fauna is so evident that it justifies two independent catalogues. A comparable division between the Jurassic and Cretaceous could not be justified however, because of the similarity of the fauna, and by the greater number of genera crossing the Jurassic-Cretaceous Boundary which is three times that for the Triassic-Jurassic Boundary. A di...
-
catalogue of mesozoic radiolarian genera part 2 jurassic cretaceous
Geodiversitas, 2009Co-Authors: Luis Odogherty, Peter Baumgartner, Elizabeth S Carter, Paulian Dumitrica, Spela Goriccan, Patrick De Wever, Alexandre N Bandini, Atsushi MatsuokaAbstract:The catalogue of Mesozoic radiolarian genera is a revision of all described genera with re-illustration of their type species. This project was organized under the auspices of the International Association of Radiolarian Paleontologists (Inter-Rad), and was carried out by the Mesozoic Working Group. This is the second of two contributions, this one devoted to the Jurassic-Cretaceous period. It contains 581 genera with re-illustration of their type species. This part shares 30 genera in common with the Triassic catalogue, most of which arose in the Carnian, Norian and Rhaetian. The sharp difference manifested between the Triassic fauna and the Jurassic-Cretaceous fauna is so evident that it justifies two independent catalogues. A comparable division between the Jurassic and Cretaceous could not be justified however, because of the similarity of the fauna, and by the greater number of genera crossing the Jurassic-Cretaceous Boundary which is three times that for the Triassic-Jurassic Boundary. A distinct characteristic of Jurassic-Cretaceous genera is the high number of nomina dubia (up to 131), contrary to the low number in the Triassic interval. This reflects, in part, the influence of Haeckelian taxonomy in earlier research on Jurassic-Cretaceous faunas prior to the application of SEM techniques.The Mesozoic Working Group has carefully reviewed and re-examined the taxonomy of all available genera, their family assignment and stratigraphic ranges. Following careful comparisons, 91 genera were declared as synonyms. The review has noted 26 homonyms which were duly notified to their corresponding authors, and were corrected previous to the publication of this catalogue. In spite of this effort, unfortunately nine homonyms still remain. Two invalid nominal genera and two nomina nuda are also reported. The systematic revisions have validated 341 genera for the Jurassic-Cretaceous interval. At the end of this catalogue 24 additional photographs are presented as support for those genera having a poor original illustration of the type species.
