Multi-disciplinary approach to paleokarst occurrence in the Eocene-Oligocene succession of the Apulia Carbonate Platform (Salento, Italy)

Carbonate platforms are subject to falls of the sea level registered in the sedimentary sequences. Traces of these exposures are represented by paleokarst features such as red paleosols, speleothems, breccias and fissures filled by sediment. All these features were recognized in the Eocene–Oligocene deposits of the Salento region (Italy) applying a combination of outcrop observations, cement fabric, cathodoluminescence, stable isotopes (δ18O and δ13C) and trace element analyses. A red paleosol on an epikarst and associated fissure fills are of Pleistocene age based on the fossil content. Speleothems are related to the sea level fall of the Eocene–Oligocene transition, based on stratigraphic contacts. Breccias that fill caves and relatively thin fissures filled by sediment were found in correspondence to the Eocene–Oligocene transition and are related to the sea level drop linked the Oi-1 Event. Stable isotopes and trace elements applied on either the bulk rock or cements allowed us to discern marine and meteoric diagenesis. The paleokarst related to the Eocene–Oligocene transition could precipitate cement at one site, and was purely erosive at another location. The proposed multi-proxy approach was successful in determining the age of the paleokarstic events, identifying the specific paleokarstic environment (epikarst vs. vadose zone), and improving knowledge on the dominant diagenetic processes (precipitation vs. physico-chemical ero sion). The success of our approach can be repeated worldwide in other carbonate ramps affected by exposure to weathering and groundwater flow.