The History of Karstification on the Upper Cretaceous and Lower Paleogene Limestones in the Wider Kozina Area

Abstract

From the time of their sedimentation until today, the Upper Cretaceous and Lower Paleogene limestones of the south-western Slovenia underwent karstification over several karst periods and were subject to a number of karstification and epikarst development phases. Due to denudation, the epikarst, where the rock is markedly dissected by typical surface karst features, moves down the transverse profile of the karst system, through the traces of former karst periods and phases. The most distinct palaeokarst surface and related subsurface palaeokarst features of the area in question were formed during the non-synchronous uplift and subaerial exposure of the Adriatic Carbonate Platform in the Upper Cretaceous and Lower Paleogene. The paralic carbonate sequences that cover the palaeokarst surface were also occasionally subaerially exposed, as evidenced by the appearance of specific karst and palaeosol features. The old traces of cavernosity of the present-day karst aquifer can be observed in the form of unroofed caves and old caves right underneath the current karst surface. Even though the area in question was definitely formed during the post-collision tectonic phases/episodes of varying intensity and although the tectonic processes were “disturbed” by the external, mainly climate-based influences (e.g. the Messinian crisis), the characteristics of the present karst system mostly result from karstification that took place in the course of gradual uplifting of the territory, most notably during the post-Miocene underthrusting of Istria under the External Dinarides.