Nauki Ścisłe i Nauki o Ziemi

Acta Geologica Polonica


Acta Geologica Polonica | 2018 | vol. 68 | No 1


The radiolarian biostratigraphy of the Middle–Upper Jurassic pelagic siliceous sediments (Czajakowa Radiolarite

Formation) in the Niedzica succession of the Pieniny Klippen Belt (Carpathians) is interpreted in terms of their

age in a stratotype section, and facies equivalents in other tectonic-facies units of this region. The siliceous sediments

are represented by radiolarian cherts and silicified limestones which are underlain and overlain by red nodular

limestones, equivalents of the Rosso Ammonitico facies. The radiolarian association includes thirty-seven

taxa belonging to twenty one genera which represent the Northern Tethyan Palaeogeographic Province. Key radiolarians

recorded provide a means of correlation with zonation schemes based on Unitary Associations defined

for the Jurassic Tethyan sediments. The age of the Czajakowa Radiolarite Formation in the stratotype section

is determined as U.A.Z.9 to U.A.Z.11 corresponding to middle Oxfordian up to Kimmeridgian. Comparison of

radiolarian biozones from the stratotype section with other facial equivalent sections in the Pieniny Klippen Belt

reveals a significant diachronism for both the lower and the upper limits of the Jurassic pelagic siliceous facies.

Przejdź do artykułu

Autorzy i Afiliacje

Marta Bąk
Sylwia Chodacka
Krzysztof Bąk
Szymon Okoński


The shallow-marine carbonate deposits of the Reuchenette Formation (Kimmeridgian, Upper Jurassic) in

northwestern Switzerland and adjacent France yield highly diverse bivalve associations, but only rarely contain

remains of pinnid bivalves. The three occurring taxa Pinna (Cyrtopinna) socialis d’Orbigny, 1850, Stegoconcha

granulata (J. Sowerby, 1822) and Stegoconcha obliquata (Deshayes, 1839) have been revised. A lectotype for

Pinna (C.) socialis was designated and the taxon is assigned herein to P. (Cyrtopinna) Mörch, 1853, the first record

of the subgenus from the Jurassic. A brief review of Stegoconcha Böhm, 1907 revealed two species groups

within the genus. Species close to the type species S. granulata are characterized by a nearly smooth anterior

shell, followed posteriorly by deep radial furrows and rows of pustules covering the dorsal flank. Another group

comprises radially ribbed species related to S. neptuni (Goldfuss, 1837). It includes among others the Paleogene

species S. faxensis (Ravn, 1902), extending the known range of Stegoconcha from the Middle Jurassic into the

Paleogene. The paper suggests a relationship between Stegoconcha and the Cretaceous Plesiopinna Amano,

1956, with S. obliquata as a possible intermediate species leading to Plesiopinna during the Early Cretaceous.

Furthermore, a possible relationship between Stegoconcha and Atrina Gray, 1842 is discussed.

Przejdź do artykułu

Autorzy i Afiliacje

Jens Koppka


Triceratium barbadense Greville, 1861a, T. brachiatum Brightwell, 1856, T. inconspicuum Greville, 1861b and

T. kanayae Fenner, 1984a, are among the most common diatoms reported worldwide from lower to middle Eocene

biosiliceous sediments. Due to complicated nomenclatural histories, however, they are often confused. A morphometric

analysis performed herein indicates that T. brachiatum is conspecific with T. inconspicuum, and that both

were previously often misidentified as T. barbadense. Triceratium barbadense sensu stricto is a distinct species

similar to Triceratium castellatum West, 1860. Triceratium brachiatum and T. kanayae are transferred herein

to a new genus, Fenneria, for which a close phylogenetic relationship with Medlinia Sims, 1998 is proposed.

A review of the geographic and stratigraphic distribution of Fenneria shows that the best constrained records of

its occurrences are found at DSDP Site 338, and ODP Sites 1051 and 1260. The ages of the base (B) and top (T)

of each species’ stratigraphic range are calibrated here to the Geomagnetic Polarity Timescale either directly or

inferred via correlation with dinocyst biostratigraphy. Latitudinal diachroneity of ~7 million years is documented

for F. brachiata, which disappears earlier in tropical and mid-latitude sites than in the northern high latitudes. These

observations, coupled with a preliminary compilation of the Chron C20n taxonomic composition of pelagic diatom

assemblages for Sites 338, 1051 and 1260, indicate that diatoms diversified palaeobiogeographically considerably

earlier than the Eocene−Oligocene Transition, as commonly believed. This study also emphasizes the importance

of the detailed examination of specimens from both museum collections and deep-sea cores as a step toward enhancing

the utility of Palaeogene diatoms in palaeoceanographic and palaeoenvironmental reconstructions.

Przejdź do artykułu

Autorzy i Afiliacje

Jakub Witkowski


This malacological analysis was conducted at a site with peat and calcareous tufas in Łapsze Niżne, Podhale

(southern Poland). The study was carried out in 6 main and several complementary sections, in which 37 mollusc

species were recognized represented by almost 11 000 specimens. The study enabled the reconstruction of

environmental changes during the accumulation of the Holocene deposits (from the Boreal Phase till present).

Conclusions drawn from these reconstructions were compared with results of malacological and palynological

studies from other sites in Podhale. As a result, regional environmental reconstructions for the Holocene of the

area were made. The specific composition, ecological structure and succession of molluscan assemblages from

Łapsze Niżne indicate a significant role for local factors, thus demonstrating the variability of environmental

conditions within a geographic region.

Przejdź do artykułu

Autorzy i Afiliacje

Witold Paweł Alexandrowicz
Marcin Szymanek
Eliza Rybska


An accumulation of glacial sediments is located near Písečná village in the depression between the Sokol Ridge

and Zlaté Hory Highlands NNE of Jeseník town (Eastern Sudetes). The accumulation lies at the lateral side

of the mountain valley of the Bělá River and fills a preglacial palaeovalley of this river. Research combining

facies analysis of outcrops, ground penetrating radar survey, interpretation drilling survey, and modelling of

the preglacial relief was undertaken at the site. According to the results obtained, the upper part of the sedimentary

accumulation represents a coarse-grained terminoglacial glaciofluvial delta of the Gilbert type. The

development of the accumulation has dominantly been driven by the preglacial morphology. Facies typical for

foresets of coarse-grained deltas represented mainly by high-density flows, cohesionless debris flows, debris

falls and less common low-density flows were found in the outcrops. The delta near Písečná prograded into

a lake dammed by the ice-sheet front in the north. The lake was bounded by the slopes of Sokol Ridge, Zlaté

Hory Highlands and Góry Parkowe on other sides. The lake level reached an altitude of up to 430 m a.s.l., as

the coarse-grained delta plain base lies at this level.

Przejdź do artykułu

Autorzy i Afiliacje

Martin Hanáček
Slavomír Nehyba
Daniel Nývlt
Zuzana Skácelová
Barbora Procházková
Zbynek Engel

Ta strona wykorzystuje pliki 'cookies'. Więcej informacji