Reconstruction of palaeoflow and depositional dynamics from the Merjasec unroofed cave, Laze Plain (central Slovenia)

Sparsely preserved unroofed cave deposits are ancient remains of cave systems. The Merjasec unroofed cave is a perfect example of poorly preserved cave deposits where conventional sedimentological study revealed a greater potential for the reconstruction of local to regional palaeoenvironmental conditions. Cave deposits are characterised by polymictic conglomerates, pebbly sandstones and flowstone belonging to five distinct sedimentary facies. Sedimentary features indicate deposition of channel-related bedforms in a narrow cave-connecting conduit, activated only during extreme pulsating floods under epiphreatic conditions. In this sense, it mimics the current hydrology of the regional system and shows that the hydrological history of the cave system is strongly dependent on climatic conditions. Moreover, this study demonstrates a methodological approach that can be successfully applied to similary exposed cave deposits elsewhere, showing that even fragmentary or eroded remnants, when analysed in detail, can significantly contribute to understanding of karst palaeohydrology.