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Research progress on a distinct Cretaceous–Paleogene boundary event bed within the “Liburnia formation” in Kras region (Pivka area, SW Slovenia)

Although the Cretaceous–Paleogene hiatus is a common feature of almost whole Adriatic Carbonate Platform s. str. (Korbar, 2009), there are at least two known exceptional sections in the SW part of the ACP that are characterized by a continuous K–Pg succession and by an unusual deposit at the K-Pg boundary that is interpreted as a major tsunamite related to the Chicxulub asteroid impact (Korbar et al., 2015, 2017a). The Kras region is built predominantly of Cretaceous to Paleogene carbonates (Jurkovšek et al., 2016), and is a type locality of the Liburnian formation. The lower boundary is still not reported in details and that is why the succession is recently tentatively named as “Liburnia formation”(Jurkovšek et al., 2016), since the name is highly debated (Korbar, 2009). At Pivka-Slavina section (PSL) in the middle part of the “Liburnia formation” we investigated unusual 4, 80 m thick intercalation of a massive coarse-grained limestone characterized by very diverse polyspecific predominantly outer-ramp microfossils (Korbar et al., 2017b). Lower boundary of the intercalation is sharp, while the massive bioclastic-intraclastic bed is characterized by fining-upward succession and up to 60 cm thick mudcap containing complete valves and bioclasts of radiolitid and requieniid rudists bivalves, as well as Maastrichtian benthic foraminifera. The mudcap is overlain by approx. 0, 5 cm thick brown soil horizon that is either infiltrated from the surface or represent a completely altered K–Pg boundary “clay” (Korbar et al., 2017a). Dark grey laminated mudstones directly overlay the soil horizon while ostracod mudstones and rare tiny benthic foraminifera characterize Paleocene part of the section.

Adriatic Carbonate Platform ; Cretaceous–Paleogene ; event bed

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