Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Frasnian-Famennian boundary" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
Stratigraphy and geological events at the Frasnian-Famennian boundary in the Southern Urals
Autorzy:
Veimarn, A. B.
Puchkov, V. N.
Abramova, A. N.
Artyushkova, O. V.
Baryshev, V. N.
Degtyaryov, K. E.
Kononova, L. I.
Maslov, V. A
Mosejchuk, V. M.
Pazukhin, V. N.
Pravikova, N. V.
Tevelev, A. V.
Yarkova, A. V.
Powiązania:
https://bibliotekanauki.pl/articles/2058843.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Frasnian-Famennian boundary
Southern Urals
conodonts
superplume
Opis:
Detailed biostratigraphic correlation of late Frasnian and Famennian sections in the Southern Urals shows that the key global scale events near the boundary of Frasnian and Famennian are clearly expressed in combination with important regional scale tectonic events. The maximum regression occured during triangularis zones time, being recorded as common hiatuses. The beginning of specific ultra- potassic mantle volcanism took place during the linguiformis Zone. Processes of olistostrome deposition, uplift of the Uraltau zone, the start of flysch deposition, and exhumation of the high pressure-low temperature Maksiutovo metamorphic complex also took place very close to the Frasnian-Famennian boundary, as the general regression coincided with active local tectonic movements as the Magnitogorsk island arc collised with the East European continent. The global scale events at the F-F boundary are connected with activity of the Late Devonian superplume, which encompassed a vast area of the Kazakhstanian, East European, Siberian, Gondwana and South Chinese plates.
Źródło:
Geological Quarterly; 2004, 48, 3; 233--244
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conodont biostratigraphy of the Frasnian-Famennian boundary in the Esfahan and Tabas areas, Central Iran
Autorzy:
Gholamalian, H.
Powiązania:
https://bibliotekanauki.pl/articles/2059517.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Iran
Late Devonian
Frasnian-Famennian boundary
biostratigraphy
conodonts
Opis:
The Frasnian-Famennian (F-F) boundary in Central Iran has been investigated on the basis of conodont faunas (34 species and subspecies) from four sections: Chahriseh near Esfahan, and Kal-e-Sardar, Howz-e-Dorah and Ghale-Kalaghu near Tabas. The F-F boundary in the Chahriseh section is located in a one-metre interval between beds EX1 and F-F9 whereas in the Kal-e-Sardar section it is at the base of bed Cly1. The F-F boundary can not be recognized in the Howz-e-Dorah and Ghale-Kalaghu sections be cause of uncon form able relation ships and erosion of the upper most late Frasnian beds indicated incidentally by reworked boulders (indicating con temporaneous tectonic activity) and by the abrupt appearance of contrasting environments, including tempestites at the base of the lower Famennian. The best conodont and palaeoenvironmental data were obtained from the Kal-e-Sardar section where a deeper marine environment prevailed during the late Frasnian, be coming shallower in the early Famennian; the Chahriseh section displays small fluctuations in sea level during the early Famennian. The conodont faunas display the inception of the Polygnathus communis group in the late Frasnian (rhenana-linguiformis zones) and the appearance of Icriodus alternatus mawsonae in the Late rhenana Zone. A new age-range is suggested for Polygnathus aequalis Klapper and Lane, from the transitans to the linguiformis zones. Three conodont biozones are represented in the late Frasnian to early Famennian of the Chahriseh section, two late Frasnian and one early Famennian in the Kal-e-Sardar section and two biozones in the late Frasnian and early Famennian of both the Howz-e-Dorah and Ghale-Kalaghu sections. Two new species are described: Polygnathus tabasianus (Early to Late crepida zones) and Polygnathus vachiki (Late rhenana-linguiformis zones).
Źródło:
Geological Quarterly; 2007, 51, 4; 453-476
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Późno dewońskie impakty
Late Devonian impacts
Autorzy:
Brachaniec, Tomasz
Brom, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/1033026.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Meteorytowe
Tematy:
Frasnian-Famennian boundary
Late Devonian
Siljan crater
mass extinction
Opis:
In 1970 the first hypothesis, which claimed that large meteorite landed in ocean at Frasnian/Famennian boundary and caused mass extinction was proposed. In Late Devonian deposits there are many potential impact evidences. Nonetheless, many years of searching for iridium anomaly, shocked minerals, microtektites and craters in the F/F boundary passage deposits have failed. The most probably crater, which could be connected with F/F boundary is Siljan Ring in Sweden.
Źródło:
Acta Societatis Metheoriticae Polonorum; 2015, 6; 34-37
2080-5497
Pojawia się w:
Acta Societatis Metheoriticae Polonorum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Devonian facies variety in Iran: volcanism as a possible trigger of the environmental perturbation near the Frasnian-Famennian boundary
Autorzy:
Mahmudy Gharaie, M. H.
Matsumoto, R.
Kakuwa, Y.
Milroy, P. G.
Powiązania:
https://bibliotekanauki.pl/articles/2058813.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Frasnian-Famennian boundary
Iran
black shales
ironstone
greenhouse
volcanism
Opis:
Upper Devonian successions surrounding the Frasnian-Famennian (F-F) boundary in Iran consist of mixed carbonate/silisiclastic deposits. The successions are characterized by conspicuous ferruginous limestones, clay-rich units, black shales, and mafic volcanic rocks that provide important insights into palaeoenvironmental conditions during this interval of Earth’s history. An increase of kaolinite/illite ratio in clays associated with the F-F boundary suggests that increased chemical weathering was facilitated by warm and humid climatic conditions. Distinctive ferruginous-oolite deposits overlying the crucial Frasnian-Famennian boundary interval indicate a high supply rate of Fe-bearing clay originated during enhanced weathering under such climatic conditions. Black shales associated with the F-F boundary are interpreted to be the result of a high primary productivity caused by an increased influx of land-derived nutrients and regional volcanic activity. Widespread rift-related, basaltic activity along eastern Laurussia and northern Gondwana during the mid-Late Devonian is believed to have contribution to this global warming surrounding the F-F boundary.
Źródło:
Geological Quarterly; 2004, 48, 4; 323-332
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Upper Devonian mercury enrichments : comparison of Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) and Atomic Absorption Spectrometry (AAS) analytical data
Autorzy:
Racki, G.
Rakociński, M.
Marynowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/2060451.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Mercury anomalies
analytical methods
geochemistry
Frasnian-Famennian boundary
Devonian-Carboniferous boundary
volcanism
Opis:
Mercury geochemistry is emerging recently as a hot topic in chemostratigraphical and facies research, owing to the diagnostic character of Hg enrichments as a proxy of volcanic activity (crucial in the context of assumed causal links between volcanic cataclysms and mass extinctions). Thus, as a prerequisite to such far-reaching interpretations, reliable analytical determinations of Hg concentrations are necessary. In conventionally performed analyses in sedimentary geochemistry, Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) is usually applied, as an analytical standard for trace elements, including Hg. However, with a detection limit (DL) of 10 ppb, such measured values have been questioned as a conclusive geochemical indicator of Hg anomalies, and, instead, far more accurate techniques, such as Atomic Absorption Spectrometry (AAS; DL = 0.2 ppb), are requested. As a preliminary test of this view, we present comparative analysis of 91 samples from three sections encompassing the key Frasnian-Famennian and Famennian-Tournaisian boundary intervals in Morocco (Lahmida), Germany (Kahlleite) and Uzbekistan (Novchomok), for which Hg concentrations were determined by both methods in the same samples. Despite some differences, especially at low Hg concentrations, both analytical methods reveal the same 12 extraordinarily enriched samples in excess of 1 ppm (with one exception, the determination error is <20%), as well as similar overall chemostratigraphic patterns characterized by a few prominent Hg spikes, with a top value of 5.8 ppm. The Hg concentrations determined by ICP-MS and AAS are significantly correlated, as high as r = 0.98 (Novchomok), even if the first method reveals a general tendency toward slightly heightened values (by ~15 to 30% for medians). Therefore, ICP-MS results can conclusively be used in mercury chemostratigraphy in order to recognize extraordinary volcanic (or other) signals, at least in the Devonian geological record. False Hg anomalies were not generated by these conventional ICP-MS determinations.
Źródło:
Geological Quarterly; 2018, 62, 3; 487--495
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Alvarez impact theory of mass extinction; limits to its applicability and the "great expectations syndrome"
Autorzy:
Racki, G.
Powiązania:
https://bibliotekanauki.pl/articles/20155.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Alvarez impact theory
mass extinction
great expectation syndrome
bolide impact
extraterrestrial marker
impact crater
Cretaceous
Paleogene
Triassic
Jurassic
Frasnian
Famennian
boundary
Opis:
For the past three decades, the Alvarez impact theory of mass extinction, causally related to catastrophic meteorite impacts, has been recurrently applied to multiple extinction boundaries. However, these multidisciplinary research efforts across the globe have been largely unsuccessful to date, with one outstanding exception: the Cretaceous–Paleogene boundary. The unicausal impact scenario as a leading explanation, when applied to the complex fossil record, has resulted in force−fitting of data and interpretations (“great expectations syndrome”). The misunderstandings can be grouped at three successive levels of the testing process, and involve the unreflective application of the impact paradigm: (i) factual misidentification, i.e., an erroneous or indefinite recognition of the extraterrestrial record in sedimentological, physical and geochemical contexts, (ii) correlative misinterpretation of the adequately documented impact signals due to their incorrect dating, and (iii) causal overestimation when the proved impact characteristics are doubtful as a sufficient trigger of a contemporaneous global cosmic catastrophe. Examples of uncritical belief in the simple cause−effect scenario for the Frasnian–Famennian, Permian–Triassic, and Triassic–Jurassic (and the Eifelian–Givetian and Paleocene–Eocene as well) global events include mostly item−1 pitfalls (factual misidentification), with Ir enrichments and shocked minerals frequently misidentified. Therefore, these mass extinctions are still at the first test level, and only the F–F extinction is potentially seen in the context of item−2, the interpretative step, because of the possible causative link with the Siljan Ring crater (53 km in diameter). The erratically recognized cratering signature is often marked by large timing and size uncertainties, and item−3, the advanced causal inference, is in fact limited to clustered impacts that clearly predate major mass extinctions. The multi−impact lag−time pattern is particularly clear in the Late Triassic, when the largest (100 km diameter) Manicouagan crater was possibly concurrent with the end−Carnian extinction (or with the late Norian tetrapod turnover on an alternative time scale). The relatively small crater sizes and cratonic (crystalline rock basement) setting of these two craters further suggest the strongly insufficient extraterrestrial trigger of worldwide environmental traumas. However, to discuss the kill potential of impact events in a more robust fashion, their location and timing, vulnerability factors, especially target geology and palaeogeography in the context of associated climate−active volatile fluxes, should to be rigorously assessed. The current lack of conclusive impact evidence synchronous with most mass extinctions may still be somewhat misleading due to the predicted large set of undiscovered craters, particularly in light of the obscured record of oceanic impact events.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies