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The Danian and Selandian calcareous benthic foraminiferal assemblages and biostratigraphy of Western Siberia

Podobina Vera

Geologos

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2011

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Vol. 17, No. 2

97--110

EN

Danian and Selandian successions in western Siberia are rich in calcareous benthic foraminifers. The assemblages with a constant systematic composition that have the widest lateral occurrence are distinguished as foraminiferal zones. The Brotzenella praeacuta Zone was established in the low-carbonate, clayey beds that form the transition from the Gankinskaya Suite to the Talitskaya Suite. These transitional beds are assigned to the Danian. The calcareous benthic foraminifers in this zone occur mainly together with agglutinated forms. The zone is traced along the areas of the largest subsidence of the Mesozoic-Cenozoic basin, principally in depressions. The transition from the Cretaceous to the Palaeogene is represented by a continuous succession, in which the Danian deposits escaped from erosion and were found to contain the B. praeacuta assemblage. In Danian rocks with a shallow-marine facies (near Beryozovo and in the Ust’-Tym depression, Fig. 1), the Bathysiphon nodosarieformis - Glomospira charoides assemblage occurs. It is dominated by primitive forms in addition to more advanced tests (mainly Late Maastrichtian relic species). The overlying Selandian (Middle Palaeocene) foraminiferal assemblages are assigned to the Talitskaya Suite. The Ammoscalaria friabilis assemblage is widely spread and is represented mainly by agglutinated quartz-siliceous forms. Beds with these species are attributed to the Ammoscalaria friabilis Zone, which can be correlated with beds in the East containing Cyclammina coksuvorovae. The Cibicidoides proprius assemblage is known from the lower and middle beds of the Talitskaya Suite in Transuralia, the Omsk Depression and more south-eastern areas; the species of this assemblage are characteristic of the Selandian.

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High resolution biostratigraphy based on planktic foraminifera across the Cretaceous-Paleogene transition at the Bidart section (SW France)

Gallala N., Zaghbib-Turki D.

Acta Geologica Polonica

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2010

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Vol. 60, no. 2

243-255

EN

Based on high resolution biostratigraphic analysis of planktic foraminifers, it is confirmed that the Bidart section (eastern margin of the Atlantic Ocean) represents a continuous Cretaceous-Paleogene (K-Pg) succession. Nevertheless, the foraminiferal species Plummerita hantkeninoides, regarded as a latest Maastrichtian marker species, is absent and Abathomphalus mayaroensis ranges to the top of the Maastrichtian (= K/Pg boundary). Pseudoguembelina hariaensis is present throughout the succession, and it is proposed herein to substitute Pl. hantkeninoides as the marker of the uppermost Maastrichtian. At least 53 out of 72 species became suddenly extinct at the K/Pg boundary, defined by the Ir anomaly (Bonte et al. 1984; Delacotte et al. 1982). The extinct species are represented by globotruncanids and large heterohelicids, characteristic of the tropical-subtropical deep photic sea water under the mesotrophic conditions of the Late Maastrichtian. The Lower Danian succession (the zones of Guembelitria cretacea, Parvularugoglobigerina eugubina, Parasubbotina pseudobulloides) is less expanded than at El Kef (Tunisia) [the Global Stratotype Section and Point (GSSP) for the Cretaceous/Paleogene (K/Pg) boundary] or at Elles (Tunisia) [its auxiliary section].

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Dańskie amonity - obecny stan wiedzy i perspektywy badań

Machalski M., Jagt J.W.M., Heinberg C., Landman N.H., Hakansson E.

Przegląd Geologiczny

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2009

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Vol. 57, nr 6

486-493

EN

To date, the strongest arguments for ammonite survival into the Danian (earliest Paleogene) are based on material from the lower Danian Cerithium Limestone at Stevns Klint (Denmark), where ammonites occur above a clay layer with impact products at its base, the latter defining the Cretaceous-Paleogene (K-Pg) boundary. The best-preserved specimen is filled with Danian sediment rather than with Maastrichtian chalk, which would be expected had this been reworked material. Arguments for ammonite survival into the Danian have also been provided by specimens from the sporomorph and calcareous nannoplankton-dated lowermost Danian strata of Meerssen Member unit IVf-7, the Netherlands. Their good preservation indicates that they were not subject to any significant transport or redeposition. However, there are no unequivocal impact-related signatures in unit IVf-7, except for rare shocked quartz grains, recorded from burrows at its base. Sections in the Manasquan Basin, New Jersey, USA, provide equivocal data as far as the problem of ammonite survival into the Danian is concerned. At the top of the Tinton Formation there is a Pinna layer replete with fossils, inclusive of ammonites. Their exquisite preservation and occurrence in monospecific clusters rule out redeposition. The Pinna layer contains exclusively late Maastrichtian microfossils. However, a clear iridium anomaly has been noted at its base. Either the New Jersey ammonites survived the K-Pg event for a short time or the iridium is not in situ due to post-depositional repositioning by percolating water. Planned work is to focus on: 1) a detailed centimetre by centimetre sampling of some Cerithium Limestone basins in Denmark in search of additional ammonite material, 2) palaeontological and taphonomic analysis of ammonites and search for impact signatures in unit IVf-7 in the Netherlands, and 3) geochemical study of the iridium anomaly in New Jersey in order to determine whether its position in respect to the ammonite-bed is original or secondary.

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Additional records of Late Cretaceous and Early Palaeogene echinoids from the Gschliefgraben (Ultrahelvetic, Upper Austria)

Kroh A., Jagt J., Wagreich M.

Acta Geologica Polonica

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2004

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Vol. 54, no. 4

551-571

EN

Late Cretaceous and Early Palaeogene echinoid faunules collected in recent years from the surface of an active mudflow at the Gschliefgraben near Gmunden (east of the Traunsee, Upper Austria) are both fairly diverse and of considerable palaeobiogeographic interest. So far, only (Late) Campanian taxa have been described and illustrated. In the present paper, notes are presented on additional Campanian, Maastrichtian and Palaeogene taxa, namely Lampadocorys? estermanni sp.nov., Lampadocorys? sp.nov. 1, Lampadocorys? sp.nov. 2, Rispolia cf. subtrigonata (CATULLO), Seunaster cf. heberti (SEUNES), Echinocorys ancileformis MOSKVIN & SHIMANSKAYA, Echinocorys ex gr. fonticola ARNAUD, Ganbirretia? sp., Micraster aturicus HEBERT in SEUNES, Micraster corcolumbarium DESOR, Micraster stolleyi (LAMBERT in DE GROSSOUVRE), Pseudogibbaster? sp., and Coraster beneharnicus SEUNES.These species indicate a close relationship with the Tethyan areas of northern Spain and SW France, the Crimea, Georgia and the northern Caucasus, although a number of holasteroid and micrasterid taxa would appear to be more common and widely distributed in boreal settings (e.g., NW Europe).