Geological structure of karst stratigraphical windows at Škocjan Caves, Slovenia

Abstract

Within the UNESCO Škocjan Caves, detailed geological structural mapping of the cave passages and of the surface above the cave revealed interesting structural-lithological characteristics of two major collapse dolines, Velika Dolina and Mala Dolina. As a result of the karst processes effects and the formation of collapse dolines, older—stratigraphically lower—carbonates of the Sežana Formation (K22−4) crop out at the surface, underlying rocks of the younger Lipica Formation (K24−5). Here we do not recognize karst windows only in a geomorphological sense but, acknowledging the characteristic lithostratigraphical relationships involved, we suggest use of the new expression “karst stratigraphical window”. Recognizing that karstic areas contain numerous collapse dolines and other doline types, we presume that many more examples of karst stratigraphical windows exist, and that these are distinct from tectonic windows. Our study showed the importance that during the making of detailed geological surface maps of karst areas, it is essential to examine features such as collapse dolines, which may be identified as karst stratigraphical windows. Therefore, providing additional geological data, information about the stratigraphic boundaries and geological structure, in areas without abundance of outcropping rocks is resulting in a more inclusive and comprehensive geological maps.