Alternate Atlantic forest and climate phases during the early Pleistocene 41 kyr cycles in southeastern Brazil

• Published in: Quaternary Science Reviews
• Main Authors: Rodríguez-Zorro, Paula A., Ledru, Marie-Pierre, Favier, Charly, Bard, Edouard, Bicudo, Denise C., Garcia Molina, Marta, Marquardt, Gisele, Rostek, Frauke, Sawakuchi, André O., Simon, Quentin, Kazuyo, Tachikawa
• Other Authors: Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de recherche pour le développement IRD : UR226-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Biodiversity Conservation, Environmental Research Institute, University of Guarulhos, Universidade de São Paulo = University of São Paulo (USP)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Subtropical front; Araucaria; Southern Hemisphere; Antarctic ice volume; Tropical forest; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarctic; Pacific; Antarc*
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03690968; https://doi.org/10.1016/j.quascirev.2022.107560

International audience The early Pleistocene was driven by 41 kyr glacial cycles that have been rarely characterized in continental records, especially in South America. Most of long-term records derive from marine records (e.g. sea surface temperatures (SST)) and have been widely used to infer past climate dynamics but implications for the continent have rarely been evaluated. We present an early Pleistocene record (COL17c) from the Colônia basin in the Atlantic forest domain in southeastern Brazil. Our aim was to integrate past environmental dynamics and the drivers of change between ca. 1.5 to 1.3 Myr at the latitude of Colônia (23°S; ca. 700 m a.s.l.). We applied a multi-proxy approach including pollen, charcoal, X-Ray fluorescence scanning (XRF), biomarkers and diatoms. We identified three glacial periods and four interglacials containing a continuous cool forest, mainly dominated by Araucaria. The glacial periods were characterized by increases in organic matter input on the lake, semi-deciduous forest, and shore and herbaceous vegetation. In contrast, the interglacials were marked by increases in evergreen forest and reduced organic matter input. We attribute these alternating phases of vegetation and lake productivity to meridional temperature differences that regulated the input of moisture at the latitude of Colônia. After 1.430 Myr, glacial and interglacial periods showed a different dynamism with an increase in Araucaria forests and drops in relative temperature, concomitant with regional long-trend cooling observed in marine records. The observed forest responses inferred from the COL17c record are in phase with regional climate features such as the development of the cold Pacific tongue and the equatorward migration of subpolar fronts, highlighting the strong influence of the Southern Hemisphere at Colônia during the early Pleistocene.