Environmental and vegetation changes in southeastern Amazonia during the late Pleistocene and Holocene

摘要

New insights about climate conditions and their effect on vegetation and lakes of southeastern Amazonia were achieved over the last 50 cal ka using recent data obtained from a filled lake located in the Serra Sul de Carajas. Our analysis was done in a sediment core (R2) comprising of faciological, palynological, isotopic and radio carbon measurement supported by Bayesian age-depth modeling, as well species distribution modeling. Wet and cool climate conditions are proposed for the mid-Pleniglacial, which is favorable to intense weathering of the lake's catchment area and the expansion of high altitude taxa (cool-adapted) into forest formations during this period. From the late Pleniglacial to the Last Glacial Maximum, a change from relatively wet to dry climate possibly converted the studied lake from oxidizing to reducing conditions, which leads to the formation of diagenetic siderites at the end of this time interval. Warming during the Pleistocene to Holocene transition caused the disappearance of cool-adapted taxa in the study site. Concomitantly, increasing precipitation allowed the expansion of forest and high lake levels. A drier early-mid Holocene produced extensive open vegetation and desiccated lakes. Current climate and environmental conditions were likely attained in the region from the mid to late Holocene. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.