Temat: middle Frasnian - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Early-Middle Frasnian transition: Biotic response to a major perturbation of the global carbon budget
Autorzy:: Balinski, A
Olempska, E.
Racki, G.
Tematy:: Early-Middle Frasnian
Frasnian
biotic response
perturbation
global carbon budget; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22463.pdf Link otwiera się w nowym oknie
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: From palaeosols to carbonate mounds: facies and environments of the middle Frasnian platform in Belgium
Autorzy:: Silva da, A. C.
Boulvain, F.
Tematy:: Belgium
middle Frasnian
carbonate platform
palaeogeography
facies
carbonate mounds; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2058840.pdf Link otwiera się w nowym oknie
Opis:: This paper provides a synthetic sedimentological overview of themiddle Frasnian carbonate platform of Belgium and associated carbonate mounds. Carbonate mounds started usually in a relatively deep, quiet subphotic environment with a crinoid-coral-sponge assemblage, then reached the fair-weather wave base and the euphotic zone with an algal-microbial facies. The upper parts of themounds are characterised by lateral facies differentiation with the algal-microbial facies protecting a central sedimentation area with a dendroid stromatoporoids facies and fenestral limestone. The lateral facies reflect different kinds of input of reworked mound material in the proximal area, from transported fine-grained sediment to coarse-grained fossil debris. On the platform, environments range from the outer zone (crinoidal facies) to stromatoporoid-dominated biostromes and to the lagoonal area of the inner zones (subtidal facies with Amphipora floatstone, algal packstone, intertidal mudstone and laminated peloidal packstone and palaeosols). These facies are stacked in metre-scale shallowing-upward cycles. The larger scale sequential organisation corresponds to transgressions and regressions, whose cycles are responsible for differentiating a lower open-marine biostrome dominated unit from an upper lagoonal unit. The last regression- transgression cycle, responsible for the platform-scale development of lagoonal facies, can be correlated with an atoll-stage evolution of the carbonate mounds belonging to the Lion Member.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

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.
Tematy:: ostracod
Early Frasnian
Frasnian
Middle Frasnian
Nevada
relationship
Alamo Event
Ostracoda
conodont
sedimentology
paleoecology; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23394.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Early-Middle Frasnian cyrtospiriferid brachiopods from the East European Platform
Autorzy:: Sokiran, E V
Tematy:: Early-Middle Frasnian
Frasnian
cyrtospiriferid brachiopod
brachiopod
East European Platform
paleontology
Russia
Brachiopoda
Cyrtospiriferidae; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21097.pdf Link otwiera się w nowym oknie
Opis:: The cyrtospiriferids are among the most important fossils in the Frasnian strata of the East European Platform (EEP). During the Early Frasnian (Palmatolepis falsiovalis Zone) the numerous and morphologically distinct Uchtospiriferinae, accompanied by very scarce Cyrtospiriferinae, are known from South Timan. The mass appearance of cyrtospiriferins on the platform at the beginning of the Middle Frasnian is linked with significant sea−level rise of Devonian Transgression−Regression (T−R) cycle IIc. At that interval these brachiopods attain their highest diversity of the entire Frasnian. The Early Frasnian type species of the genus Uchtospirifer is here revised, and subfamily Uchtospiriferinae re−established. Cyrtospirifer schelonicus, C. rudkinensis, C. mylaensis sp. nov., and C. tenticulum are described from the Middle Frasnian of NW and central regions of EEP and Middle Timan.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Early and Middle Frasnian brachiopod faunas and turnover on the South China shelf
Autorzy:: Ma, X -P
Becker, R.T.
Li, H.
Sun, Y.-Y.
Tematy:: Early Frasnian
Middle Frasnian
Frasnian
paleontology
brachiopod fauna
South China shelf
Devonian
Brachiopoda
Cyrtospirifer
faunal turnover; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21029.pdf Link otwiera się w nowym oknie
Opis:: The first appearance of the brachiopod Cyrtospirifer and related forms in the Late Devonian of South China significantly postdates the beginning of the Frasnian and the entry of the group in other parts of the world. Scattered data from different sections suggest that its first entry, associated with the emergence of other plicate spiriferids, such as theodossid and conispiriferid brachiopods, was late in the Middle Frasnian. At the same time, many rhynchonellids disappeared or became extinct locally in South China. This brachiopod faunal overturn near the Palmatolepis punctata–Early Pa. hassi zonal boundary is the most significant event in the Early–Middle Frasnian of South China, characterized by about a 35% loss of existing species and the flourishing of the plicate spiriferids, which was coeval with the end of a major biogeochemical perturbation recently recognized in the Pa. punctata Zone. By contrast, atrypid brachiopods do not seem to show any significant diversity change. The brachiopod faunal change was probably related to a (local?) transgressive event in South China, which also brought new pelagic faunas northwards into some intra−shelf deeper water areas, such as the Shetianqiao area in central Hunan Province. Fifteen brachiopod species are described and illustrated, which include some taxa that are first recorded or recognized in South China, e.g., the spiriferid Pyramidaspirifer, which is now known from both North America and South China. One new species, Desquamatia qiziqiaoensis, is erected.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Benthic ostracods from the Early-Middle Frasnian transition in the north-western East European Platform, Russia
Autorzy:: Evdokimova, I O
Tematy:: benthic ostracod
ostracod
Early-Middle Frasnian
Frasnian
paleontology
East European Platform
Russia
Ostracoda
Main Devonian Field; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21796.pdf Link otwiera się w nowym oknie
Opis:: Pronounced changes in benthic ostracod associations in the north−west part of the East European Platform, across the Early–Middle Frasnian (Devonian) transition, track a marine transgression event. More than 80 ostracod species belonging to the Eifelian Mega−Assemblage were recorded. Cavellinidae and Acratiidae generally dominate the Early Frasnian Sargaevo Horizon. Middle Frasnian ostracod associations of the Semiluki Horizon are more diverse and are characterised by different dominant both geographically and stratigraphically, resulting from significant palaeo−basin bottom relief and benthic biotope differentiation. The ostracod associations are indicative of very shallow, well oxygenated semi−restricted epeiric environment, with occasional marine influence, alternating with short periods of open shelf conditions. The relative abundance of ostracod species in the different associations, and faunal diversity indices, show considerable variations throughout the Early–Middle Frasnian, and suggest a less restricted position within an intra−platform setting in the Middle Frasnian, relative to a more restricted ostracod habitat in the Early Frasnian. The succession of Early–Middle Frasnian micro−benthic associations within the Main Devonian Field seems to be of a regional scale, and resulted from a marine regression−transgression couplet, corresponding to eustatic cycles IIb–IIc. This was paired with synsedimentary tectonic subsidence in adjacent areas of the north−east East European Platform, progressively improving marine water circulation in the extremely shallow−water shelf seas.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Faunal and facies changes at the Early-Middle Frasnian boundary in the north-western East European platform
Autorzy:: Zhuravlev, A V
Sokiran, E.V.
Evdokimova, I.O.
Dorofeeva, L.A.
Rusetskaya, G.A.
Malkowski, K.
Tematy:: fauna change
Early-Middle Frasnian
East European Platform
Conodonta
Brachiopoda
Ostracoda
correlation
carbon isotope
Frasnian
Main Devonian Field; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20261.pdf Link otwiera się w nowym oknie
Opis:: Multidisciplinary study of the Early–Middle Frasnian boundary in the north−western East European Platform (Main Devonian Field) allows evaluation of changes in facies, brachiopod, ostracod, and conodont associations, as well as carbon isotope composition. Brachiopod and ostracod faunas, characterized by predominance of rhynchonellids, spiriferids, podocopids, and platycopids in the Early Frasnian, and by predominance of spiriferids, palaeocopids, and kloedenellocopids in the Middle Frasinan, demonstrate significant changes in dominance and diversity likely caused by regressiontransgression couplets in the extremely shallow−water environment. Changes in diversity of the conodont associations, represented mainly by shallow−water polygnathids and spathognathids, are controlled by sea−level fluctuations as well; however significant evolutionary turnover is absent. Deepening pulses lead to an increasing in diversity of both the benthic and nectic groups, whilst regressions cause diversity fall due to progressive habitat reduction. Most prominent decreasing in the fauna diversity is observed in the late Early Frasnian (Dubnik time) coinciding with the regressive phase of the Late Givetian to Early Frasnian eustatic cycle. Positive−negative δ¹³C excursion, detected in brachiopod calcite from the early interval of the Middle Frasnian, can be correlated with global isotopic perturbations near the Frasnian substage boundary: the positive 2.6‰ δ¹³C excursion is probably linked with enhanced primary production in high−nutrient regimes in the epeiric sea.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Gastropod succession across the Early-Middle Frasnian transition in the Holy Cross Mountains, southern Poland
Autorzy:: Krawczynski, W
Tematy:: paleontology
gastropod succession
Early-Middle Frasnian
Frasnian
transition
Holy Cross Mountains
Southern Poland
Polska
Gastropoda
Eotomariidae
Elasmonematidae
bioevent
Devonian; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21568.pdf Link otwiera się w nowym oknie
Opis:: Gastropod response to a marked carbon isotopic geochemical anomaly across the Early–Middle Frasnian transition (Palmatolepis transitans–Palmatolepis punctata conodont zones) has been analysed along the southern Laurussian shelf, mainly within the Dyminy Reef in the Holy Cross Mountains. Gastropods are represented by three reefal associations (Kowalatrochus sanctacrucensis, Euryzone kielcensis, and Grabinopsis guerichi associations), and an impoverished open−shelf Straparollus laevis assemblage. The most severe diversity crisis is connected to the disappearance of local low−energy muddy habitats, as a result of a transgressive pulse (Middlesex Event) and benthic habitat changes tied to strongly fluctuating carbon cycling; this has been observed at the highly diverse Kadzielnia−type assemblage. Fifteen taxa have been recognised in this distinctive Early Frasnian mud−mound association, including six (probably endemics), which are unknown from the Middle Frasnian. The disappearance of three relict Givetian species (Euryzone delphinuloides, Straparollus laevis, and Goniasma? zarecznyi) is also recorded. Other species probably migrated into the shallower water part of Dyminy Reef and persisted in the Middle and Late Frasnian. The Middlesex Event and the earlier major biogeochemical perturbation seem to have less serious effects for evolution of gastropods in the Polish−Moravian part of the Laurussia shelf than the catastrophic Frasnian–Famennian extinction. Two new taxa are described: Frydiella kaimi gen. et sp. nov. (Eotomariidae) and Heidelbergeria czarnieckii gen. et sp. nov. (Elasmonematidae).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Conodont-based event stratigraphy of the Early-Middle Frasnian transition on the South Polish carbonate shelf
Autorzy:: Pisarzowska, A
Sobstel, M.
Racki, G.
Tematy:: conodont association
stratigraphy
Early-Middle Frasnian
Frasnian
Polska
carbonate shelf
biostratigraphy
carbon isotope
paleoecology
Devonian
Palmatolepis transitans
Palmatolepis punctata; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22673.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Conodont ecology in the Early-Middle Frasnian transition on the South Polish carbonate shelf
Autorzy:: Sobstel, M
Makowska-Haftka, M.
Racki, G.
Tematy:: conodont
ecology
Early-Middle Frasnian
Frasnian
Southern Poland
carbonate shelf
paleoecology
Holy Cross Mountains
deposit
Palmatolepis transitans
Palmatolepis punctata; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23066.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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