High-latitude Cretaceous–Paleogene transition: New paleoenvironmental and paleoclimatic insights from Seymour Island, Antarctica

Abstract

The Filo Negro Section, on Seymour Island (Antarctic Peninsula), is a fossiliferous section with great potential for Late Cretaceous–Paleogene studies, which also presents an iridium anomaly layer. However, it has not been thoroughly studied in terms of integrated high-resolution paleontological and multi-proxy records yet. Palynomorphs and geochemical proxies are used herein to assess paleoenvironmental and paleoclimatic changes recorded at this section during the Maastrichtian–Danian transition. In addition, statistical tests are applied to our numerical palynological data (cluster analysis, Mann Kendall Trend test and χ2-test) in order to further support our interpretations. The P/G ratio (peridinioid/gonyaulacoid dinoflagellate cysts) was adopted as a paleoproductivity proxy, whereas the T/M ratio (terrestrial/marine palynomorphs) was used to infer proximal/distal depositional settings. The sedimentary succession was divided into three intervals, based on a cluster analysis. We infer humid, relatively warm conditions for the latest Maastrichtian, and cool paleoclimates after the K–Pg transition. This is supported by the Fe/K ratio, which depicts a general trend toward drier climates in the early Danian. A marked increase in terrestrial palynomorphs, along with a general Ti/Al ratio increasing-upwards trend, implies more proximal settings above the maximum flooding surface, marked at 9.9 m. The P/G and Ba/terrigenous elements ratios imply a marine paleoproductivity drop around the K–Pg transition, remaining low during the earliest Danian. We also refined the previous position of the K–Pg transition in this section, placing it within 9.5 to 9.6 m, based on dinoflagellate cysts biostratigraphical analysis and geochemical data (iridium anomaly and increase in siderophile elements).