Facies dependence of spore assemblages and new data on sedimentary influence on spore taphonomy

Palynological studies have been undertaken on Lower Carboniferous (Mississippian) rocks encountered in boreholes from the North Sea to the Baltic Sea (Rügen) in Northern Germany and from an outcrop at the northern border of the Rhenish Slate Mountains in western central Germany. The studied sections belong to different facies realms within the neritic shelf facies. They begin with very near shore coastal clastic facies in the North Sea and onshore Northern Germany, ranging into carbonate platform facies at Rügen, and then into platform slope facies at the northern margin of the Rhenish Slate Mountains. The focus of this study is the analysis of the relationship between sedimentary facies and spore assemblages; therefore, spores were considered only as sedimentary particles. Thus, it was necessary to create a new spore classification scheme based only on relevant sedimentary features. The new scheme distinguishes three classes of miospore based on shape, with each class subdivided into three subclasses based on features of ornament. The diversity of the spore assemblages and the total palynofacies have also been studied. Correlating palynological results from sections representing different sedimentary facies has led to a better understanding of the influence of sedimentary facies on spore assemblages. Correlations have been made at two stratigraphical levels. Regional correlation is undertaken on the Upper Viséan from the coastal clastic facies (North Sea, Northern Germany), the carbonate platform facies (Rügen) and the marginal platform slope facies (Velbert). Local correlation within the carbonate platform facies has been attempted using samples of Mid-Viséan TS zone from four boreholes on Rügen. Certain important differences have been observed. The local correlation at Rügen shows a decrease in spore frequency and spore assemblage diversity related to increasing resedimentation within subsided blocks of the platform. The composition of spore assemblages, strongly dominated by round-shaped spores, is nearly the same in all sections. The regional correlation shows clear proximal–distal trends for the total number of spores and also the diversity and composition of spore assemblages. A strong decrease in triangular and transitional spores from proximal to distal facies was observed. In conclusion, spore assemblages seem to be strongly influenced by sedimentary facies as well as by different sedimentary processes within the facies. Facies dependence of spore assemblages is shown to be an important factor for stratigraphical use of spores and for establishing vegetational and climatic trends.