Lithostratigraphy and biostratigraphy of the uppermost Cretaceous to lowermost Palaeogene shallow-marine succession: top of the Adriatic Carbonate Platform at the Likva Cove section (island of Brač, Croatia)

Abstract

The Likva Cove section on the island of Brač (Croatia) represents a rare example within the Adriatic Carbonate Platform (AdCP) succession of the basal Palaeocene limestones overlying the uppermost Maastrichtian shallow-platform limestones with evidence of only a brief stratigraphic hiatus at the Cretaceous/Palaeogene (K/Pg) contact. Detailed study of the 50-m-thick section resulted in the description of eight lithofacies arranged into six lithostratigraphic units: (A) rudist limestones, (B) deposits with coral–stromatoporoid patch reefs, (C) bindstones, and (D) fine-grained limestones with benthic and rare planktonic foraminifera in the uppermost Maastrichtian (comprising microfossil assemblage biozones I and II), and (E) limestones with benthic foraminifera (mostly discorbids), ostracods and rare planktonic foraminifera, and (F) ostracod–discorbid limestones in the lowermost Palaeocene (representing microfossil assemblage biozone III).The K/Pg contact is constrained between the last occurrence of Maastrichtian benthic and rare planktonic foraminifera, and the first occurrence of Danian planktonic and benthic foraminifera. The uppermost Cretaceous bed represents a firmground, but low biostratigraphic resolution precludes defining duration of a probable short-lasting hiatus at the K/Pg contact. Planktonic foraminifera are mixed with benthic forms in a 3.5-m-thick interval comprising the K/Pg contact as a consequence of decreased depositional rate and probable storm influence.Top of the section contains well developed coral patch reefs intensely karstified during a long-lasting regional unconformity, which in the studied part of the AdCP commenced in the early Palaeocene, i.e. later than at most parts of the platform. Therefore, the end of AdCP deposition should be locally extended into the Palaeocene in both its NW and SE parts.