Marcin Barski

Organic-walled dinoflagellate cysts as a tool to recognize carbonate concretions: an example from Oligocene flysch deposits of the Western Carpathians

Organic-walled dinoflagellate cysts as a tool to recognize carbonate concretions: an example from Oligocene flysch deposits of the Western Carpathians Carbonate concretions found within the Krosno shales (Polish Outer Carpathians) have formerly been interpreted as limestone exotics. Both the concretions and the host shales yield well preserved organic-walled dinoflagellate cysts. The dinoflagellate cyst assemblages provide valuable age-diagnostic information: they indicate a mid-Oligocene age and prove the concretionary origin of the carbonates. Detailed analysis of relative abundance, biodiversity and paleoecology of the dinoflagellates from concretions provides additional information on the sedimentary environment and the model of concretion formation.

Formation of intracontinental basins in the opposite corners of the Tabas block as coeval structures controlled by transpressional faulting, Iran

The interaction of strike-slip faults in their restraining junctions allowed for the coeval formation of the Tabas and Abdoughi Basins and led to their inversion during the late Cenozoic. The intracontinental basins filled with Neogene and Quaternary deposits were controlled by large-scale dextral transpression along major faults that bounded the Tabas block, which is a part of the Central Iranian block. The anastomosing strike-slip fault pattern facilitated the development of both basins in opposite corners of the Tabas block. The subsided areas were formed as a result of interaction between the restraining junctions of strike-slip faults and thrusts. Flexural loading caused by the uplifted series of thrust sheets resulted in the depression of the opposite fault slabs, which permitted deposition of Neogene sediments. Deformation according to the “bookshelf” mechanism can be considered as a consequence of accommodation of the shortening of the area north of the Main Zagros thrust and externally imposed shearing along the Great Kavir (Doruneh) fault during the collision of the Arabian and Eurasian plates. Related processes of transpression and counterclockwise rotation of the tectonic blocks included in the Central Iranian block favored the interaction of strike-slip faults. The change of far-field stress and continuous transpression caused inversion of the basins and formation of Neogene folds in the northern and southern corners of the Tabas block. The geomorphic features observed along these strike-slip faults and on the thrust surfaces bounding the folds display their recent activity, consistent with present-day seismicity and geodetic measurements within the Central Iranian block.

Eodinia poulseni sp. nov., a dinoflagellate cyst from Middle Jurassic of Central Poland

A new species of dinoflagellate, Eodinia poulseni, is described from the Middle Jurassic of Central Poland. Light and scaning electron microscopy shows that this species has a complex cyst wall consisting of autophragm and ectophragm. Eodinia poulseni sp. nov. has similarities to some common Middle Jurassic species, especially when separate hypocysts are observed. Important differences between Eodinia pachytheca, Mosaicodinium mosaicum, Wanaea acollaris, W. cornucavata and Hurlandsia rugarum are discussed. Some phylogenetic and environmental relationships to the Early Cretaceous freshwater species Hurlandsia rugarum are suggested. H. rugarum shows similarity in archaeopyle, overall shape and tabulation formula but is acavate and also distinct from E. poulseni in time.