Discontinuity surfaces of possible microkarst origin in the Viivikonna Formation (Kukruse Stage, Middle Ordovician) of Estonia

The purpose of this paper is to describe two discontinuity surfaces encountered in the Viivikonna Formation that display well-developed microkarst-like features and to interpret the environmental conditions of their formation. Considering morphology and facial position of the discontinuity surfaces studied it seems reasonable to presume their subaerial origin. They possibly represent analogues to modern coastal microkarst forms in temperate areas. The exposed seafloor could not have had any appreciable topographic relief above sea level. As the Baltoscandian epicontinental sea owned an extraordinarily flat and very gently sloping seafloor (Jaanusson, 1973), a sea level rise of only a few centimetres would have rapidly submerged hundreds of metres or even kilometers of coastal limestone.