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First discovery of Mississippian trace fossils in the Świebodzice Unit from the Witoszów region (SW Poland)

Muszer Jolanta

Geological Quarterly

2020

Vol. 64, No. 4

838--860

Abundant and moderately diverse trace fossil assemblage have been discovered for the first time in mudstones of the Pogorzała Formation from the Witoszów region, SW Poland. Fifteen ichnospecies including fourteen ichnogenera are described. The ichnofauna is dominated by Dictyodora liebeana and contains numerous Palaeophycus tubularis, rarer Archaeonassa fossulata, Archaeonassa isp., Chondrites cf. intricatus, Curvolithus simplex, Diplopodichnus biformis, Lockeia isp., ?Lophoctenium isp., Nereites isp., Phycosiphon isp., Protovirgularia isp., ?Psammichnites isp., Taenidium isp. and one ichnospecies of fish swimming trails, Undichna cf. britannica. Some other structures (wave ripples influenced by microbial mats and zigzag structures) also occur. The trace fossil assemblages differ in various exposures, but three of them are similar and display the Dictyodora liebeana ichnoassemblage. It is represented mostly by the ethological categories fodinichnia and repichnia, with fewer pascichnia, domichnia and cubichnia. This new data from the Świebodzice Unit sheds light on the palaeontology, age and palaeoenvironment of the Pogorzała Formation. The occurrence of D. liebeana and U. cf. britannica indicates the Mississippian age of most mudstones studied, formerly considered Upper Devonian. The trace fossil assemblage belongs to the non-standard Nereites ichnofacies, without graphoglyptids. The lithological features of mudstones, trace fossil assemblage and poverty of macrofauna, testify to their deposition in a deeper sedimentation zone below storm wave base, most likely in dysaerobic, pro-delta conditions. This study suggests that rocks containing D. liebeana may form a correlative horizon in the Świebodzice Unit.

Miospore evidence for the Carboniferous age of rocks from the Świebodzice Unit (Sudetes, SW Poland)

Pluta K., Górecka-Nowak A.

Geological Quarterly

2018

Vol. 62, No. 1

120--133

The paper provides new results of palynological studies of rocks from the Świebodzice Unit. An abundant Carboniferous miospores were found in rocks of the Pogorzała Formation from the southern part of this unit. These miospores occur in rocks containing also macrofloral and marine macrofaunal fossils, partly reworked, which were usually considered Upper Devonian. Two miospore sub-assemblages of different ages and colours have been distinguished. One of them consists of poorly preserved miospores, dark in colour, which indicate the Late Visean–Serpukhovian age of the rocks. The other sub-assemblage, found only in a few samples, consists of much lighter and well-preserved miospores of the Asturian age. Their presence is considered as a result of stratigraphical leakage. Observation of the miospore colour indicates that the thermal event occurred after the Late Devonian and before the Asturian and the palaeotemperature exceeded ~180°C. These new data indicate that the geological history of the Świebodzice Unit lasted longer and was much complex than it was previously considered.