Evidence and facial position of reef mounds in the Lower Cambrian of the Doberlug-Torgau area

The facies of reef mounds from the Lower Cambrian of the Doberlug-Torgau Synclinorium is described for the first time. The examined material was taken from a well situated in the NE area of the synclinorium. The biosedimentary bodies are analysed in respect of their spatial geometry and internal construction. On the basis of the bio- and sedimentary facies as well as of palaeoecological examinations, the palaeobiocoenoses and their spatial distribution are comprehended. The environment of the reef mounds is interpreted as a shallow tilted ramp in the middle subtidal. Under low or absent siliciclastic influx archaeocyaths and calcimicrobes settled within the photic zone. Calcimicrobes stabilised the sediment and established the base for the development of reef mounds. A self-organising ecosystem with a characteristic fauna developed. Within the reef mounds a vertical faunal differentiation is detected. Regular archaeocyaths and calcimicrobes predominate in the basal part and the periphery of the mounds, whereas irregular archaeocyaths predominate in the core. Widespread calcimicrobial meadows are only found at the base of the mound.