Eocene palaeoenvironments and palaeoceanography of areas adjacent to the Drake Passage: insights from dinoflagellate cyst analysis

• DOI: 10.1111/pala.12601
• Publication Date: 2022-06-13T05:17:14Z
• Authors: Cecilia R. Amenábar; G. Raquel Guerstein; Marta I. Alperin; Elbio D. Palma; Silvio Casadío; Alexandra Belgaburo; Martín Rodríguez ...
• Keywords: Dinoflagellate; Dinocyst; Paleogene

Abstract A proper understanding of the palaeoceanographic evolution Drake Passage during Palaeogene is hampered by lack precise tools to date and correlate sedimentary units areas adjacent region. In this work, considering recently published radiometric U–Pb dates, we revised age a previous dinoflagellate zones for middle upper Eocene Austral–Magallanes Basin. The quantitative analysis late cyst assemblages from different localities close allowed us reconstruct palaeoenvironmental conditions possible surface ocean currents time in area. Assemblages dated between 41.3 38.1 Ma represent relatively warm waters inner shelf settings, while those ranged 36 35 reflect coastal with cool, nutrient‐rich waters. proposed circulation pattern, based on cysts distribution Ma, agrees results palaeoclimatic numerical model simulation performed shallow opening 100 m depth. At c . several Antarctic gonyaulacacean taxa tolerant warmer were replaced some peridinacean species better adapted colder conditions. This change could be linked progressive deepening that estimated have reached 1000 depth promoting cooling South Atlantic. Such passage would enabled stronger flows Pacific Atlantic Ocean, which reflected increase cosmopolitan species.