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1

Continuous versus pulsed origination and extinction and biozones

Trammer J.

Acta Geologica Polonica

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2014

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Vol. 64, no. 4

361--366

EN

The count of biozones as an approximate measure of the origination and extinction rates of index taxa (mostly species) is proposed. The mean number of extinctions of these taxa per m.y. is 1.136 (Palaeozoic mean 0.902, Mesozoic mean 1.680, Cenozoic mean 0.789). In contrast with the majority of taxa, the originations and extinctions of index taxa, as well as of other taxa belonging to biostratigraphically important systematic groups, seems to be continuous.

2

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].

3

Lower Devonian conodonts from the Karlik Valley and Na Branzovech sections in the Barrandian area, Czech Republic, and their significance for Pragian conodont zonation

Slavik L.

Acta Geologica Polonica

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2001

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Vol. 51, nr 3

253-271

EN

Two Early Devonian sections used for this study display a markedly different facies development and lie opposite limbs of the central Barrandian synform, in the stratotype area of the Pragian Stage. The present biostratigraphical information based on 18 species with a total of 350 conodont specimens is mostly related to the late Lochkovian and early Pragian, whilst the remaining parts of the Pragian involve mostly long-range conodont species. The late Lochkovian conodonts correspond to two zones eurekaensis and delta. The latest Lochkovian zone pesavis was found in the northwestern limb, but not on the opposite side. The absence of pesavis Zone in the south (Koneprusy) and, as it has been newly shown, in the south-east of the central Barrandian synform (Karlik Valley) suggests that a prominent lowstand sedimentary starvation affected much larger areas than only the tops of elevated ridges. The lower two thirds of the Pragian sequences can be zoned using two newly suggested conodont zones steinachensis and serratus, respectively, that are defined by the first and last occurrences of these taxa.The occurrence of Latericriodus steinachensis (AL-RAWI) eta morph. marks the lower third and the entry of Peleksygnathus serratus serratus JENTZSCH corresponds to the base of the middle third of the Pragian. The newly suggested stratigraphical applicability of these two species can effectively substitute the pre-existing sulcatus and kindlei subdivisions that have no zonal species representation in the stratotype area. The first occurrence of Latericriodus bilatericrescens bilatericrescens (ZIEGLER) seems to indicate the base of the Emsian in the Na Branzovech section. The entry of this taxon is connected with the black-shale Graptolite Event within the latest Dvorce-Prokop Limestone that is several beds higher than the levels usually considered for entry of a debatable taxon Polygnatus pireneae. The base of the Graptolite Event gives better chance for the correlation of the Pragian-Emsian boundary than any of the underlying levels. Evolution of the Barrandian conodont assemblages shows many parallels with those of Morocco and Carnic Alps.

4

The youngest members of the folded Miocene in the Andrychów region (Southern Poland)

Wójcik A., Jugowiec M.

Przegląd Geologiczny

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1998

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Vol. 46, nr 8/2

763-770

EN

Deposits of the folded Miocene appear in the surrounding of Andrychów. In the profile of the sediments occurring here, clays with gravels and boulders, mainly flysch ones, clays with gravels of crystalline rocks, limestones andflysch deposits, dark clays with organic detritus and large flysch olistoliths as well as sandy clays and sands are distinguished. The youngest deposits, developed as gray clays, sandy clays with an irregular and thin sandy inter-lamination, have been identified in the Bulówka stream. Based on the presence ofC. coalithus and C. cf. calyculus the age of the studied deposits has been determined as the nannoplankton zone NN9a/8 that corresponds to the Lower Pannonian in a stratigraphic division for Central Paratethys.