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Wyszukujesz frazę "conodont" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
New upper Givetian to basal Frasnian conodont faunas from the Tafilalt (Anti-Atlas, Southern Morocco)
Autorzy:
Aboussalam, Z.S.
Becker, R.T.
Powiązania:
https://bibliotekanauki.pl/articles/2059516.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Morocco
Frasnes Event
Givetian
Frasnian
conodont taxonomy
conodont biostratigraphy
Opis:
Conodont faunas, mostly from previously unsampled sections of the Tafilalt (eastern Anti-Atlas, Morocco) and spanning the upper Givetian to basal Frasnian, include first records of species for the region and NW Gondwana as well as new taxa: "Ozarkodina" maroccanica n. sp., Polygnathus aequidivisus n. sp., Po. dengleri sagitta n. ssp., Po. jorfensis n. sp., Po. saevus n. sp., Po. tafilensis n. sp., and Schmidtognathus longicavus n. sp. The morphology of Tortodus subsymmetricus n. sp. suggests relation ships of Tortodus with Frasnian ancyrognathids. Other taxa are described in open nomenclature: Po. cristatus n. ssp., Icriodus aff. I. symmetricus, Skeletognathus aff. Sk. norrisi, and enigmatic supposed Pb elements (Gen. et sp. indet.). Ctenopolygnathus lanei Kuzmin (1995) is emended and distinctive morphotypes are recognized in Ct. angustidiscus and Po. collieri. Mesotaxis falsiovalis Sandberg et al. (1989) is a subjective junior synonym of the widely over looked M. guanwushanensis (Tian, 1988). There vised regional lithostratigraphy and conodont sequences allow to refine the upper Givetian zonation. The former Upper disparilis Zone is subdivided into succes sive Po. dengleri sagitta and Po. dengleri dengleri subzones. The basalmost Frasnian Ancyrodella rotundiloba pristina Zone (= MN 1 Zone) is preserved as a thin, condensed lime stone just at one locality (Bine Jebilet). The over lying Frasnes Event Beds (Lower Styliolinites) seem to fall in the subsequent Ad. rotundiloba soluta Zone (MN 2 Zone). Records of rare taxa, such as Po. paradecorosus, Po. Pollocki Morphotype 1, old est Po. webbi, Ct. angustidiscus, and Ct. lanei may be help ful for correlation into distant areas or shallower facies.
Źródło:
Geological Quarterly; 2007, 51, 4; 345-374
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ostracods and facies of the Early and Middle Frasnian at Devils Gate in Nevada: Relationship to the Alamo Event
Autorzy:
Casier, J -G
Berra, I.
Olempska, E.
Sandberg, C.
Preat, A.
Powiązania:
https://bibliotekanauki.pl/articles/23394.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ostracod
Early Frasnian
Frasnian
Middle Frasnian
Nevada
relationship
Alamo Event
Ostracoda
conodont
sedimentology
paleoecology
Opis:
In order to document the Alamo Event and to investigate its influence on shallow−marine environments, we undertook a study of ostracods, conodonts, and analysis of the sedimentology of the lower member of the type Devils Gate Limestone. Six major carbonate microfacies (MF1–MF6) ranging from open−marine environments below storm wave base to pre−evaporitic supratidal lagoons were recognized. The sedimentological study detected no important sedimentological changes during the Alamo Event; only an influx of detrital material and lithoclasts indicate that an unusual event had occurred. Ostracods are generally rare or absent in the lower member of the Devils Gate Limestone, and only 2,000 carapaces, valves and fragments were extracted; from these some 26 taxa were identified. Two new species, Voronina? eureka and Serenida dorsoplicata are proposed. The ostracods belong to the Eifelian Mega−Assemblage and their distribution was influenced by strong salinity variations. Because of the rarity and low diversity of ostracods and conodonts in samples collected from the lower part of the lower member of the Devils Gate Limestone it is not adequate to demonstrate conclusively an extinction event close to the Alamo Event Bed. Nevertheless the greater abundance and diversity of ostracods above this bed seems to indicate that the Alamo Event did not result in significant extinction of ostracod taxa in this shallow water setting. The ostracod fauna present in the lower member of the Devils Gate Limestone suggests faunal exchanges between Nevada and the Russian Platform via the Western Canadian platform.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 4; 813-828
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Post-extinction survivor fauna from the lowermost Famennian of Eastern North America
Autorzy:
Day, J
Over, D.J.
Powiązania:
https://bibliotekanauki.pl/articles/21376.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Famennian
brachiopod fauna
conodont fauna
stratigraphy
fauna
Frasnian
Conodonta
extinction
survivor fauna
Brachiopoda
North America
paleontology
Opis:
An earliest Famennian (Late Devonian) shell bed was discovered in the Hanover Shale Member of the Java Formation 1.4 meters above the Frasnian–Famennian (F–F) boundary in western New York. The invertebrate shelly fauna of the shell bed (Lower Palmatolepis triangularis conodont Zone), provides information on taxonomy of an outer shelf benthic association during the survival interval of recovery in the Appalachian foreland basin soon after the terminal Upper Kellwasser event marking the F–F mass extinction. Shelly invertebrates are extremely rare in the upper Hanover immediately above and below the shell bed. Abundance of brachiopod valves and remains of other groups in the shell bed reach 80–100 valves/100 cm2. Elongate valves of the linguloid brachiopod Barroisella cf. B. campbelli have preferred alignments roughly parallel to direction of down−slope flow in the deep−water foreland basin depositional setting. The brachiopod fauna is dominated by the representatives of Retichonetes, Barroisella, Cyrtospirifer, Tylothyris, and Praewaagenoconcha. Rare elements include species of Thiemella, Schizophoria, Ripidiorhynchus?, Chapinella?, an indeterminate rhynchonellid, Ambocoelia, and extremely rare Orbiculoidea. Forms including Cyrtospirifer hornellensis, Tylothyris mesacostalis, Praewaagenoconcha speciosa, and few others are late Frasnian carryovers. The range inception of Thiemella leonensis is just above the F–F boundary (Upper Kellwasser horizon) in the upper Hanover Shale shell bed in the western Appalachian foreland basin.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Frasnian-Famennian events in a deep-shelf succession, Subpolar Urals: biotic, depositional, and geochemical records
Autorzy:
Yudina, A B
Racki, G.
Savage, N.M.
Racka, M.
Malkowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/21692.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Famennian
biotic record
Frasnian
geochemical record
depositional record
geochemistry
Kellwasser crisis
conodont
biostratigraphy
paleontology
lithostratigraphy
carbon isotope
Opis:
The Frasnian–Famennian (F–F) boundary is well biostratigraphically documented in the Palmatolepis−rich deposits exposed along the Syv’yu River in the lower slopes of the Subpolar Urals. The thin−bedded calcareous−clayey−siliceous deep−slope succession of the Vorota Formation appears to represent continuous Domanic−type deposition throughout the world−wide carbonate crisis time, without evidence for the basal Famennian hiatus or a large−scale sedimentary perturbation within a regressive setting. The northernmost Laurussian sequence exhibits many well known signatures throughout the broad F–F timespan: the appearance of organicand clay−rich deposits, icriodontid and radiolarian blooms, and a correlative shift of several geochemical proxies towards hypoxic and high−productivity regimes, perfectly recorded by positive 13Ccarb excursions of +3.5‰. Integrative biotic, microfacies and geochemical data substantiate a longer−term oceanographic destabilization, attributable to multiple Earth−bound triggering factors in (episodically enhanced?) greenhouse climate and punctuated eustatic sea−level highstands, superimposed on the elevated deposition of organic carbon−rich sediments during the Upper Kellwasser Event. Unsteady eutrophicated, and oxygen−depleted ecosystems during the F–F biotic crisis interval could be assumed, especially when intensified by various spasmodic tectono−volcanic phenomena in the incipiently closing Ural Ocean.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emergence and collapse of the Frasnian conodont and ammonoid communities in the Holy Cross Mountains, Poland
Autorzy:
Dzik, J
Powiązania:
https://bibliotekanauki.pl/articles/21673.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Ammonoidea
paleobiology
Conodonta
Polska
collapse
population variability
conodont
community
Frasnian
change
Devonian
evolution
Holy Cross Mountains
paleontology
ammonoid
Opis:
The dominant factor in faunal succession of conodonts in the Frasnian of Poland is the apparent immigration of species originating allopatrically in other regions. Each immigration event usually changes the population variability of a local species (character displacement). Only a few lineages show their phyletic evolution within the studied area. Attempts to distinguish conodont species on the basis of platform element shape failed in some of the latest Frasnian palmatolepidids. Even at the apparatus−based generic level, certain ramiform elements of the apparatus appear much more diagnostic than the platforms. Correlative value of the late Frasnian palmatolepidids of unknown apparatus structure is thus questionable. The evolution of platform elements in Ancyrodella offers a more solid basis for age determination although their great population variability makes resolution rather low and requires the population approach. The panderodontids Belodella(?) tenuiserrata sp., B. minutidentata sp. nov., B. robustidentata sp. nov., prioniodontid Icriodus kielcensis sp. nov., enigmatic monospecific Playfordiidae fam. nov., prioniodinids Dyminodina planidentata gen. et sp. nov., D. anterodenticulata sp. nov., D. kovalensis sp. nov., Pluckidina kielcensis gen. et sp. nov., P. slupiensis sp. nov., P. robustipegmata sp. nov., and P. lagoviensis sp. nov., derived polygnathid Avignathus bifurcatus sp. nov., probably secondarily simplified polygnathid Nicollidina gen. nov., and palmatolepidids Kielcelepis gen. nov., Lagovilepis gen. nov. and Klapperilepis gen. nov. are proposed.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conodont-based event stratigraphy of the Early-Middle Frasnian transition on the South Polish carbonate shelf
Autorzy:
Pisarzowska, A
Sobstel, M.
Racki, G.
Powiązania:
https://bibliotekanauki.pl/articles/22673.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
conodont association
stratigraphy
Early-Middle Frasnian
Frasnian
Polska
carbonate shelf
biostratigraphy
carbon isotope
paleoecology
Devonian
Palmatolepis transitans
Palmatolepis punctata
Opis:
Early to Middle Frasnian (E–MF) epicontinental sequences are investigated in five representative localities of the Holy Cross Mountains and Cracow region, with emphasis on conodont biostratigraphy, to evaluate the regional stratigraphic and biotic context of a major biogeochemical perturbation in global carbon cycling. Conodont associations from the Palmatolepis transitans to Palmatolepis punctata Zone boundary beds are dominated by the shallow−water polygnathid and ancyrodellid fauna in the South Polish epicontinental successions, and first appearances of index palmatolepid species are delayed due to facies control of pelagic environments during intermittent drowning of the carbonate shelf. Thus, identification of the zonal boundary is based mainly on species of Ancyrodella, and five distinctive ancyrodellid levels in the succession across the E–MF interval enable refined correlation of the sections studied, especially when paired with chemostratigraphic proxies. Prominent conodont biofacies shifts coincided with eustatic deepening, which is correlated with the Timan, Middlesex, and early Rhinestreet events, respectively. Trends in the conodont dynamics, mortality and diversity, partly replicated by the benthic biota (especially shelly faunas and crinoids), indicate that the faunal turnovers correlate also with the main δ¹³C excursions and related changes in trophic conditions. The E–MF transitional interval, marked by short−term sea−level fluctuations, is distinguished by a change from relatively diversified biofacies to more homogenous, mostly impoverished faunas. The latter change is a biotic response to the beginning of a prolonged (ca. 0.5 Ma) positive δ¹³C anomaly, probably paired with unsteady eutrophic and partly anoxic regimes. The late Pa. punctata Zone negative carbon isotope anomaly is synchronous with the second large−scale pelagic biofacies remodelling, including mesotaxid extinction. A stabilization of the carbon cycle and its return to normal background values at the start of the Early Palmatolepis hassi Zone coincide with conodont biofacies diversification and recovery of reef−related biofacies. With the exception of collapsed, endemic Kadzielnia−type mud−mound biota and a moderate biodiversity depletion due to overall ecosystem stagnation, no significant extinction events can be demonstrated, even if the large−scale changes in carbon cycling during the E–MF timespan are of higher−amplitude than the celebrated carbon isotopic anomalies related to the Frasnian–Famennian mass extinction. Thus, this regional succession in detail confirms that the large−scale punctata Isotopic Event (= Pa. punctata Event) is correlated neither with catastrophic enviromental nor radical biotic changes.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 4; 609-646
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conodont ecology in the Early-Middle Frasnian transition on the South Polish carbonate shelf
Autorzy:
Sobstel, M
Makowska-Haftka, M.
Racki, G.
Powiązania:
https://bibliotekanauki.pl/articles/23066.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
conodont
ecology
Early-Middle Frasnian
Frasnian
Southern Poland
carbonate shelf
paleoecology
Holy Cross Mountains
deposit
Palmatolepis transitans
Palmatolepis punctata
Opis:
Well exposed Early–Middle Frasnian (E–MF, Palmatolepis transitans to Palmatolepis punctata zonal interval) deposits of the Holy Cross Mountains, in particular the reference Wietrznia section at Kielce, were studied in terms of conodont biofacies dynamics. Frequency of the conodont elements has been controlled mostly by depositional rate in hemipelagic muddy lithofacies and post−mortem gravity sorting during lateral redeposition in storm−generated, talus−like and encrinite layers. The conodont assemblages are dominated by a highly varying proportion of polygnathid, icriodontid, and ancyrodellid fauna. Major biofacies turnovers coincided with the deepening pulses corresponding to Timan, Middlesex, and early Rhinestreet global events. Trends in the conodont dynamics, mortality, and diversity point that the biotic shifts also coincide with the large−scale δ¹³C excursions as a record of changing trophic conditions during the major biogeochemical perturbation. A gradual decline of the Early Frasnian Ancyrodella reef−dwelling community correlates with the minor positive and succeeding larger negative δ¹³C excursion, and this is paired with a replacement by, mostly sparse, polygnathid and polygnathid−icriodontid biofacies, as well as with a short−term Belodella acme in mud−mounds areas. The distinctive habitat deterioration in pelagic and reef ecosystems is broadly correlative with the Domanik Crisis. The progressive biofacies unification is a conodont response to onset of the prolonged (ca. 0.5 Ma) δ¹³C enrichment, probably linked with high−stress life conditions due to eutrophication and partly anoxic regimes. A negative carbon isotope excursion in the late Pamatolepis punctata Zone is marked by the second major biofacies turning point during the Rhinestreet transgression, as recorded primarily in a final mesotaxid extinction, and highlighted also by decrease of conodont size and increased mortality of juveniles. After stabilization of δ¹³C values and a return to the background level across the Palmatolepis punctata–Palmatolepis hassi zonal transition, renewed biofacies diversification, in particular re−appearance of reef−related ancyrodellid fauna, took place. In addition, a large−scale migration event among palmatolepids and polygnathids during sea−level rise, mainly from the East European Platform, characterised this Middle Frasnian interval.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 4; 719-746
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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