New geochemical and stratigraphic data from the K/Pg transition in the Adriatic-Dinaric Carbonate Platform (Karst, Italy)

The Cretaceous-Paleogene (K/Pg) boundary marks one of the most significant mass extinctions in Earth's history, associated with meteorite impact and major environmental changes. Understanding the geochemical, sedimentological, and biogenic signatures of this transition is essential to reconstruct paleoenvironmental conditions and biogeochemical responses after global events. While deep-sea K/Pg boundary deposits have received extensive attention, the shallow-marine sedimentary record remains less explored. The K/Pg transition is recorded in the shallow water carbonates of the Adriatic-Dinaric Carbonate Platform on the Karst Plateau but is often poorly exposed. An 80 m-long core was drilled in Padriciano (Trieste) in an attempt to retrieve a continuous rock record, under the auspices of the Interreg Italy-Slovenia Kras-Carso II project. This effort seeks to enhance the geological heritage of the region by fostering cross-border research collaborations and promoting sustainable development. Detailed analyses on the core will help to enhance knowledge of the K/Pg which is recognized as one of the key geosites in the area. The Padriciano core comprises shallow-water carbonates, predominantly wackestones and packstones, exhibiting variable textural features. The succession includes intraclast-rich horizons, laminated intervals, brecciated layers, and karstified surfaces, reflecting a complex depositional and diagenetic history characterized by episodes of subaerial exposure and subsequent post-depositional alterations. Facies analyses, biostratigraphic investigations, and geochemical analyses (XRF, gamma-ray spectrometry, δ¹³C and δ¹⁸O) were carried out on the core. The integration of these data enhances the stratigraphic resolution of the K/Pg boundary in shallow-marine environments and provides new insights into environmental changes that occurred across the K/Pg transition.