PALEOZOIC EVOLUTION OF THE ROMANIAN PART OF THE MOESIAN PLATFORM: AN OVERVIEW

Based on the review of the litho- and biostratigraphy of the first sedimentary cycle in the northern part of the Moesian Platform (Romania), the Paleozoic evolution of the Moesian realm is presented, along with comments of the proposed models of palaeogeographic affinity. During the Cambrian-Carboniferous cycle, sedimentation largely took place within three main basins, separated by basement highs. Various marine environments prevailed, with episodes of continental deposition during Eifelian and Carboniferous. Restricted, euxinic environments characterized the Late Ordovician-Silurian and Upper Devonian intervals. Marine carbonate platform conditions prevailed throughout the Givetian-Visean times, with restricted lagoonal environments (from brackish to hypersaline) in the Middle Devonian to open sea (normal marine) environments in the Carboniferous. In the Romanian part of the Moesian platform coarse elastics accumulated in the Ordovician and most of the Middle Devonian, while the Silurian and Lower Devonian are mainly pelitic. Carbonate rock accumulation expanded at the end of the Middle Devonian and peaked during the Early Carboniferous. Lithology and facies of carbonate sediments suggest that latest Middle to Upper Devonian carbonate sedimentation took place in tidal flat conditions, from supratidal, sabkha, to intertidal and subtidal, euxinic environments. Detrital sedimentation with local coal measures prevailed during the Lower and Upper Carboniferous, with clastics interfingering in places with carbonate sediments.