Post-impact event bed (tsunamite) at the Cretaceous-Palaeogene boundary deposited on a distal carbonate platform interior

We show crucial evidence for the Cretaceous–Palaeogene (K–Pg) boundary event recorded within a rare succession deposited in an inner-platform lagoon on top of a Mesozoic, tropical, intra-oceanic (western Tethys) Adriatic carbonate platform, which is exposed at Likva cove on the island of Brac (Croatia). The last terminal Maastrichtian fossils appear within a distinct 10–12 cm thick event bed that is characterized by soft-sediment bioturbation and rare shocked-quartz grains, and is interpreted as a distal tsunamite. Directly overlying this is a 2 cm thick reddish-brown clayey mudstone containing planktonic foraminifera typical of the basal Danian, and with elevated platinum-group elements in chondritic proportions indicating a clear link to the Chicxulub asteroid impact. These results strongly support the first discovery of a “potential” K–Pg boundary tsunamite on the neighboring island of Hvar, and these two complementary sections represent probably the most complete record of the event among known distal shallow-marine successions.