Cretaceous-Paleocene transition along a rocky carbonate shore: Implications for the Cretaceous-Paleocene boundary event in shallow platform environments and correlation to the deep sea

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). *Diethard.G.Sanders@uibk.ac.at Current address: Biologiezentrum-Oberösterreichisches Landesmuseum, Johann-Wilhelm-Klein-Strasse 73, A-4040 Linz, Austria. Sanders, D., Keller, G., Schlagintweit, F., and Studeny, M., 2019, Cretaceous-Paleocene transition along a rocky carbonate shore: Implications for the CretaceousPaleocene boundary event in shallow platform environments and correlation to the deep sea, in Adatte, T., Bond, D.P.G., and Keller, G., eds., Mass Extinctions, Volcanism, and Impacts: New Developments: Geological Society of America Special Paper 544, p. 1–XXX, https://doi.org/10.1130/2019.2544(06). © 2019 The Authors. Gold Open Access: This chapter is published under the terms of the CC-BY license and is available open access on www.gsapubs.org. OPEN ACCESS GO LD Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/4929473/spe544-06.pdf by Princeton University user on 27 January 2020