ABSTRACT The Cretaceous-Paleocene (K/P) boundary intervals are rarely preserved in successions of shallow-water limestones. Here, we describe a shallow rocky shore on the active orogenic wedge of the eastern Alps (Austria) fringed by a carbonate platform that was largely cannibalized by erosion. We compared this succession with similar nearshore environments globally, as well as the deep sea, to gain a better understanding of the environmental response to the K/P boundary transition. In the eastern Alps, Cretaceous and Paleocene lithofacies across the K/P boundary transition are separated by a hardground that formed during subaerial exposure and that terminates Upper Maastrichtian limestone with planktic foraminiferal assemblages deposited at neritic depth during zone CF3 (ca. 66.500 Ma). Above the hardground, there are beachrocks with early Danian zone P1a(1) assemblages, which indicate the hardground spans about ~600 k.y. of nondeposition and/or erosion. During the early Danian, the marine transgressive fringe fluctuated between “shoreface to emersion” environments, depositing limestones rich in bryozoans, rhynchonellids, coralline algae, and rare planktic foraminifera along with abraded, bored, and/or encrusted clasts eroded from older rocks. Repeated short subaerial exposure is marked by vadose diagenesis and hardgrounds, including an ~1.5 m.y. interval between magnetochrons C29n to C28n and planktic foraminiferal zones P1b to P1c(2). Comparison with platform carbonate sequences from Croatia, Oman, Madagascar, Belize, and Guatemala, as well as nearshore siliciclastic environments of southern Tunisia, Texas, and Argentina, across the K/P boundary transition revealed surprisingly similar deposition and erosion patterns, with the latter correlative with sea-level falls and repeated subaerial exposure forming hardgrounds. Comparison with deep-sea depositional patterns revealed coeval but shorter intervals of erosion. This pattern shows a uniform response to the K/P boundary transition linked to climate and sea-level changes, whether in shallow nearshore or deep-sea environments, with climate change tied to Deccan volcanism in magnetochrons C29r-C29n.

Abstract The Eastern Mediterranean is one of the most seismically active regions in Europe. Crete, located in the centre of the Eastern Mediterranean, should experience tsunamis resulting from large magnitude earthquakes or volcanic eruptions. At three locations, boulders were observed that may relate to tsunami or storm events. At Lakki, the size of the boulders slightly favours a tsunami origin for deposition. By contrast, at Kommos, boulder size and geomorphology are consistent with storm parameters in the Mediterranean. The most compelling evidence for tsunami transport is found at Diplomo Petris, where a lithologically varied grouping of large boulders (≤690 t) is exposed at sea level. The calculated storm wave heights (15 m) required to transport the observed boulders significantly exceeds winter averages: therefore, these accumulations are interpreted as tsunami deposits. Radiocarbon dating of encrusting biological material was undertaken to constrain periods of boulder motion. Encrustations from Diplomo Petris and Lakki predate the 365 CE earthquake, suggesting that this event transported the largest boulders; the first time that boulder deposits have been identified on Crete from this tsunami. Therefore, these data are important for developing local and regional hazard assessments but also to inform numerical models of tsunami propagation in the Mediterranean.