Lake sedimentary processes and vegetation changes over the last 45k cal abpin the uplands of south‐eastern Amazonia

Abstract

ABSTRACTThis study addresses paleoclimate influences in a southern Amazonia ecotone based on multiproxy records from lakes of the Carajás region during the last 45k cal abp.Wet and cool environmental conditions marked the initial deposition in shallow depressions with detrital sediments and high weathering rates until 40k cal abp.Concomitantly, forest and C3 canga plants, along with cool‐adapted taxa, developed; however, short drier episodes enabled expansion of C4 plants and diagenetic formation of siderite. A massive event of siderite formation occurred approximately 30k cal abpunder strong drier conditions. Afterwards, wet and cool environmental conditions returned and persisted until the Last Glacial Maximum (LGM). The LGM was marked by lake‐level lowstands and subaerial exposure. The transition from the LGM to the Holocene is marked by the onset of oscillations in temperature and humidity, with an expansion of forest and canga plants. Cool taxa were present for the last time in the Carajás region ~ 9.5–9k cal abp.After 10k cal abp, shallow lakes became upland swamps due to natural infilling processes, but the current vegetation types and structures of the plateaus were acquired only after 3k cal abpunder wetter climatic conditions.