A 21000 cal years paleoclimatic record from CacoLake, northern Brazil: evidence from sedimentary and pollen analyses

• Published in: Palaeogeography, palaeoclimatology, palaeoecology Vol. 189; no. 1-2; pp. 25 - 34
• Main Authors: Sifeddine, A, Spadano Albuquerque, AL, Ledru, M, Turcq, B, Knoppers, B, Martin, L, Zamboni de Mello, W, Passenau, H, Landim Dominguez, J, Campello Cordeiro, R, Abra, J J, da Silva Pinto Bittencourt, AC
• Format: Journal Article
• Language: English
• Published: 01-01-2003
• Subjects: Brazil, Maranhao; Northern Hemisphere
• ISSN: 0031-0182

Sedimentological studies including seismic profiles, mineralogy and organic geochemistry on two cores from the center and margin of CacoLake, Maranhao State, northern Brazil, revealed variable climatic and environmental conditions during the last 21 cal kyr BP. Between 21 and 17 cal kyr BP, during the Late Glacial Maximum, regional climate was predominantly dry, interrupted by short humid phases, as reflected by a succession of very thin layers of sand and organic matter. The Late Pleistocene climate was relatively wet as is suggested by rapid lake-level rise and forest expansion. The Late Pleistocene humid climate differed significantly from present conditions. We suggest that Late Glacial humid conditions were the consequence of intensification of the Inter-Tropical Convergence Zone or shifts of its position, resulting in Antarctic cold-front occurrences. The abrupt climatic changes during this period were marked by siderite deposition into CacoLake, which appears to be related to regional hydrologic changes linked to global/Northern Hemisphere events. The Holocene was characterized by lower moisture availability and a distinct dry period until 7 cal kyr BP, in response to South American insolation conditions.