| Institution: | 1. Instituto Tecnológico Vale, Rua Boaventura da Silva 955, Nazaré, Belém, Pará, 66055-090 Brazil;2. Instituto Tecnológico Vale, Rua Boaventura da Silva 955, Nazaré, Belém, Pará, 66055-090 Brazil
Department of Environmental Science and Technology, Central University of PB, Bathinda-151001, PB, India;3. Universidade de São Paulo, Centro de Energia Nuclear, Agricultura, Laboratório C, 14, Av. Centenário, 303, São Dimas, Piracicaba, SP, 13400-970 Brazil;4. Vale, South Africa, Gerência de Meio Ambiente – Minas de Carajás, Estrada Raymundo Mascarenhas S/N Mina de N4, Parauapebas, Pará, 68516 000 Brasil |
| Abstract: | This study addresses paleoclimate influences in a southern Amazonia ecotone based on multiproxy records from lakes of the Carajás region during the last 45k cal a bp. Wet and cool environmental conditions marked the initial deposition in shallow depressions with detrital sediments and high weathering rates until 40k cal a bp. 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 a bp under 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 a bp. After 10k cal a bp , 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 a bp under wetter climatic conditions. |
