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Taxonomy and palaeoecology of the Late Cretaceous (Campanian) Phymatellidae (lithistid demosponges) from the Miechów and Mogilno-Łódź synclinoria (southern and central Poland)

Świerczewska-Gładysz Ewa, Jurkowska Agata

Annales Societatis Geologorum Poloniae

2023

Vol. 93, No. 3

269--304

Phymatellid demosponges are common fossils in the Campanian deposits of central Europe. In Poland, the Campanian phymatellids were known mostly from the opoka facies of the Miechów Synclinorium (southern Poland), where they occur mainly in the characteristic horizons of siliceous nodules in the lower Campanian opoka succession. Similarly preserved early Campanian phymatellids were identified in a redeposited lithistid assemblage in the Neogene gravels, exposed in the Bełchatów Lignite Mine (Mogilno-Łódź Synclinorium, central Poland). Rare phymatellids were noted for the first time in the upper Campanian gaize of the Miechów Synclinorium. The taxonomic descriptions of 16 phymatellid species presented here, including one new species, Kalpinella fragilis, completes existing knowledge of the taxonomic diversity of these sponges in the Late Cretaceous basins of central Europe. The present study also supplements the data on the stratigraphic ranges and spatial distribution of these species. The palaeoecology of Cretaceous phymatellids is discussed on the basis of their occurrence in the various facies.

Opoka – a mysterious carbonate-siliceous rock: an overview of general concepts

Jurkowska Agata, Świerczewska-Gładysz Ewa

Geology, Geophysics and Environment

2022

Vol. 48, no. 3

257--278

The opoka is a carbonate-siliceous marine sedimentary rock, forming a thick succession of Upper Cretaceous age in Poland and in another regions of Europe. This rock has been studied for over 150 years, but only the use of modern analytical techniques enables for the formulation of its mineralogical definition, which identifies the distinct features of opoka and allows it to be distinguished from other rocks (e.g. chalk, gaize). Parallel to the petrographic research on opoka, its palaeobathymetric interpretations, which were based on the palaeotectonic models of Danish-Polish Trough inversion has been revised. Depending on the model of palaeotectonic history, opoka has been interpreted as a deep-water or shallow facies, without detailed petrographic studies of its mineralogical composition. The paper presents various aspects of opoka, including: history of the term, nomenclature, mineralogical composition, microtexture and palaeoecological significance of Cretaceous opoka. New data which permit precise definition of this rock term, and its mineralogical composition are discussed in the light of palaeoecological reconstructions, bathymetry and existing models of opoka distribution.