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Wyświetlanie 1-5 z 5
Tytuł:
Distribution of latest Givetian-Frasnian Atrypida [Brachiopoda] in central and western North America
Autorzy:
Day, J
Powiązania:
https://bibliotekanauki.pl/articles/22776.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
brachiopod fauna
fauna
Atrypida
mass extinction
Brachiopoda
Givetian
Frasnian
Devonian
biogeography
biostratigraphy
distribution
North America
paleontology
Opis:
Diverse atrypid brachiopod faunas characterize very late Givetian-early Frasnian deposits of Devonian Transgressive-Regressive (T-R) cycle IIb in North America which feature species of Desquamatia (Seratrypa), Desquamatia (Independatrypa), Pseudoatrypa, Radiatrypa, Spinatrypina (S.), S. (Exatrypa), Spinatrypa (S.), Davidsonia, and possibly Iowatrypa Middle Frasnian faunas are not well documented in much of North America. Middle Frasnian deposits of T-R cycle IIc in the Great Basin, Iowa, and the southern Northwest Territories and Mackenzie shelf feature species of Neatrypa, Pseudoatrypa, Radiatrypa, D. (Seratrypa), Spinatrypa, and possibly Costatrypa. Radiatrypa does not carry over into late Frasnian rocks of T-R cycle IId in North America. Genera common to late Frasnian deposits of T-R cycle IId-1 in central and western North America include widespread species of Pseudoatrypa, Spinatrypa, Costatrypa, Iowatrypa. D. (Seratrypa) and Neatrypa were restricted to the tropical platforms of western Canada at that time. Very late Frasnian brachiopod faunas of T-R cycle IId-2 yield species of Pseudoatrypa, Spinatrypa, Iowatrypa, and Pseudoatrypa? (southwest US only). Available data on Late Frasnian brachiopod records in North American subtropical platforms (New Mexico and Iowa) indicate that two successive stepped late Frasnian extinction events affected those faunas, coinciding with the Lower Kellwasser Event and the Frasnian-Famennian (F-F) Event. Over half of the atrypid genera represented in late Frasnian North American faunas survived the first wave of extinctions (Lower Kellwasser Event). The surviving species, recorded in very late Frasnian deposits of Devonian T-R cycle IId-2, became extinct during the final crisis associated with the F-F Event.
Źródło:
Acta Palaeontologica Polonica; 1998, 43, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Revision of latest Givetian-Frasnian Atrypida [Brachiopoda] from central North America
Autorzy:
Day, J
Copper, P
Powiązania:
https://bibliotekanauki.pl/articles/20627.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Late Frasnian
fauna
brachiopod fauna
Frasnian
Late Devonian
Devonian
Atrypida
taxonomy
North America
Givetian
Brachiopoda
paleontology
Opis:
The brachiopod fauna of the Middle-Late Devonian cratonic carbonate platform deposits of the Iowa Basin, central North America, contains twenty species of the order Atrypida, some of which are types for widespread genera common in Middle and Late Devonian faunas. The latest Givetian-early Frasnian deposits yield a diverse fauna consisting of ten species (two new) included in Desquamatia (Independatrypa), D. (Seratrypa), Pseudoatrypa, Radiatrypa, Spinatrypa (Spinatrypa) and Spinatrypina (Exatrypa). Many of these forms occur in, or are closely similar to species known from, coeval faunas of central and western Canada. Middle Frasnian deposits of northern Iowa contain two species included in Spinatrypa (S.) and Pseudoatrypa, both of which are new. Late Frasnian strata of the Iowa Basin yield eight species included in Costatrypa, Iowatrypa, Pseudoatrypa, and Spinatrypa (Spinatrypa), some of which are widespread in other subtropical and tropical faunas of the western US and western Canada. The taxa Pseudoatrypa witzkei sp. n., Spinatrypa (S.) bunkeri sp. n., Spinatrypa (S.) thompsoni sp. n., and Spinatrypina (Exatrypa) johnsoni sp. n. are proposed. Pseudoatrypa? sp. from the very late Frasnian of southern New Mexico is also illustrated.
Źródło:
Acta Palaeontologica Polonica; 1998, 43, 2
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:
Porównanie podatności magnetycznej (MS) i wskaźników geochemicznych środkowego i górnego franu w Kanadyjskich Górach Skalistych: implikacje dla analiz paleoklimatycznych i paleośrodowiskowych oraz interpretacji zdarzenia punctata
Comparison of magnetic susceptibility (MS) and other geochemical proxies from the Middle-Late Frasnian of the Canadian Rocky Mountains: implication for paleoenvironmental and paleoclimatic analyses and interpretations of the punctata Event
Autorzy:
Śliwiński, M. G.
Whalen, M.
Day, J.
Powiązania:
https://bibliotekanauki.pl/articles/2074752.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
późny dewon
podatność magnetyczna
zdarzenie punctata
pierwiastki śladowe
wycieczka geochemiczna
izotopy trwałe
zbiorniki osadowe Kanady zachodniej
Late Devonian
magnetic susceptibility
punctata Event
trace elements
stable isotopes
Western Canada Sedimentary Basin
Opis:
Ongoing magnetostratigraphic and geochemical studies (including major and trace element geochemistry and stable isotopes of C, N, O) in the Canadian Rocky Mountains are providing insight into the paleoenvironmental changes of the mid-Frasnian punctata Event, a prominent marine geochemical perturbation. The data is evaluated with 1) a regional sequence stratigraphic perspective and 2) within the context of a rapidly changing Late Devonian world, characterized by numerous sedimentological and faunal perturbations leading up to the eventual Frasnian-Fammenian (F/F) mass extinction. Proxies for bottom water paleoredox conditions (Mo, V, U), oceanic primary productivity (δ13Corg, δ15Nbulku, Cu, Ni, Ba), changes in detrital input (Si, Al, K, Ti, Zr), and magnetic susceptibility display similar trends, indicating that these proxies and MS variations are inherently linked. The observed excursions suggest that changes in detrital input were the main driver of a bioproductivity increase. Elevated organic matter export from the photic zone likely led to the deposition and later preservation of organic-carbon rich facies under facilitated conditions of bottom water suboxia-anoxia. These geochemical trends were likely influenced by eustatic sea level change, but may have been enhanced by pulses of coincident orogenic activity and pulses of terrestrial afforestation. The rise and expansion of the first true forests is thought to have drastically altered nutrient fluxes to the oceans via increases in pedogenesis and the expansion of a mature soil profile. Our work is intended to complement the growing body of research aimed at elucidating the causes and understanding the effects of terrestrial and marine events of the P. punctata biozone and, more broadly, at understanding the Earth-system changes of the Late Devonian leading up to the F/F boundary.
Źródło:
Przegląd Geologiczny; 2010, 58, 12; 1152-1160
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Field Magnetotransport of the Pressure Induced Organic Superconductor (BEDT-TTF)$\text{}_{3}$Cl$\text{}_{2}$2H$\text{}_{2}$O
Autorzy:
Lubczyński, W.
Caulfield, J.
Singleton, J.
Hayes, W.
Kurmoo, M.
Day, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933345.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Nj
Opis:
The magnetotransport of single crystals of (BEDT-TTF)$\text{}_{3}$Cl$\text{}_{2}$2H$\text{}_{2}$0 was studied in the Pressure range 10÷20 kbar at continuous magnetic fields up to 15 T and at temperatures down to 700 mK. Above 12.5 kbar a single series of Shubnikov-de Haas oscillations is observed, corresponding to about 0.5-1% of the cross-section of the first Brillouin zone. A superconducting state with the highest transition temperature close to 3 K is stabilised between 10.2 kbar and 13.5 kbar.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 777-779
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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