Calcispheres as a source of lime mud and peloids - evidence from the early Middle Devonian of the Prague Basin, the Czech Republic

Several types of peloids are present in the Lower and Middle Devonian limestones of the Prague Basin (uppermost part of the Trebotov Limestone of the Daleje-Trebotov Formation and Chotec Formation, uppermost Emsian-Eifelian) and are interpreted as being of calcispheral, echinoderm, and/or calcimicrobial origin. Possible mechanisms of peloid formation, the mode of life of calcispheres and their role in the accumulation of Paleozoic lime mud are discussed. Mass occurrences of peloids and calcispheres are characteristic features of the Chotec Formation (Eifelian, costatus-kockelianus conodont zones). It is concluded that specific environmental conditions, such as a higher nutrient load, existed during the sedimentation of this unit, probably in response to the Basal Chotec event.