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An exceptional 47-m-thick succession of Maastrichtian to Paleocene inner-platform carbonates is exposed in the Dalmatian island of Hvar (Adriatic Sea, Croatia) in a seaside locality called Majerovica. The middle part of this succession comprises a ~5 m thick intraformational massive deposit, which is underlain by well-bedded peritidal inner-platform limestones containing latest Maastrichtian rudists and shallow water benthic foraminifera. This deposit includes a polygenic, matrix-supported carbonate breccia characterized by ripped-up platform limestone lithoclasts, up to boulder sized, and polygenic microbreccia in a muddy matrix. The microbreccia contains rare small intraclasts of pelagic mudstone containing terminal Maastrichtian planktonic foraminifera. The deposit is overlain in turn by mudstone containing a planktonic foraminiferal association belonging to the P0 and P Zones of the basal Paleogene, and by shallow-water muddy limestones containing planktonic foraminifera belonging to the P1 Zone. While facies suggest that the deposit was emplaced over the inner platform by a single large tsunami, the biostratigraphic assessment of this section and the presence of enhanced concentrations of platinum group elements, such as iridium in the topmost part of the massive deposit, lend support to the hypothesis that this tsunamite is related to the K-Pg event, triggered by the Chicxulub impact in Yucatán. This is potentially the first case of a tropical carbonate platform sedimentary succession recording the K-Pg event, which provides a new constraint for modeling both the western Tethyan paleogeography and the catastrophic aftermaths of the Chixculub impact at the Cretaceous-Paleogene boundary.

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 Bra c (Croatia). The last terminal Maastrichtian fossils appear within a distinct 10-12 cm thick event bed that is characterised by soft-sediment bioturbation and rare shocked-quartz grains, and is interpreted as a distal tsunamite. Directly overlying this is a 2 cm thick reddishbrown 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 neighbouring island of Hvar, and these two complementary sections represent probably the most complete record of the event among known distal shallow-marine successions.

Abstract

Planktonic foraminifera were quantitatively analyzed across the Santonian succession and their boundaries at the Jebel Ennahli and Ettout sections, northern Tunisia. The continuous sedimentary succession is dominated by hemipelagic facies, allowing a good biostratigraphic correlation for this time interval. Fifty-fi fe planktonic foraminiferal species belonging to 13 genera have been identifi ed. The distribution pattern of 17 heterohelicids and 38 trochospiral forms reveals the identifi cation of 12 major bio-events and allows establishment of three zones based on heterohelicids and fi ve zones based on trochospiral forms. Trochospiral based zones are from the base to the top: 1) Dicarinella primitiva Interval Zone, 2) Dicarinella concavata Interval Zone, 3) Dicarinella asymetrica Total Range Zone, 4) Globotruncanita elevata/Globotruncana arca Concurrent Range Zone, and 5) Globotruncanita ventricosa Interval Zone. The heterohelicid planktonic foraminiferal zones are: 1) Pseudotextularia nuttalli Interval Zone, 2) Sigalia carpatica Interval Zone, and 3) Ventilabrella eggeri/Planoglobuliina manuelensis Concurrent Range Zone. The bioevents and planktonic foraminiferal zones were correlated with previously published works especially on Tunisia and other areas. The lowest occurrence (LO) of Dicarinella asymetrica is the only planktonic foraminiferal datum recorded across the Coniacian/Santonian boundary (CSB). It occurs slightly below the LO of the inoceramid Platyceramus cycloides cycloides representing a good proxy for the CSB. The Santonian/Campanian boundary in the studied sections is characterized by a major faunal turnover represented by the LO of Ventilabrella and Planoglobulina and the LO of Globotruncana and Globotruncanita slightly above. The boundary interval is also characterized by the highest occurrence (HO) of Sigalia, Dicarinella, and Whiteinella.

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