Fossil assemblages reflecting processes of the early development of the Prague Basin (Bohemian Massif, Czech Republic)
Abstract
The assemblages from all fossiliferous localities in the south-western part of the Prague Basin were studied in detail. Species distribution and comparison of locality assemblages were analyzed to trace any distribution pattern of fossils.
As a result three regions, characterized by specific fossil associations, were distinguished. These regions correspond to distribution of prevailing facies and lithological associations only very approximately.
It seems that all facies associations occur in each region. The distribution pattern of fossil assemblages was more controlled by other environmental features.
Chemistry of the environment, especially water acidity that was directly influenced by coeval subaeric volcanism, is considered to be responsible for low primary diversity, the prevalence of animals with organo-phosphatic shells, their spatial distribution and subsequent secondary taphonomic processes reducing diversity of the fossil record in affected sediment. Thus, initial colonization of the Prague Basin and its early communities reflected stressful conditions.
Inhospitable conditions were locally improved by hydrothermal fluids accompanying the volcanism.