Moreira Turcq Patricia auteur aut IRD Turcq Bruno auteur aut IRD Moreira L. S. auteur aut IRD Amorim M. auteur aut IRD Cordeiro R. C. auteur aut IRD Guyot Jean-Loup auteur aut IRD text journalArticle eng text/pdf born digital access Climatic conditions are one of the most important factors affecting hydrological processes in fluvial systems. Higher discharges are responsible for higher erosion, greater transport, and also higher deposition. Consequently, sediment accumulation in Amazonia floodplain river-connected lakes can be directly related to hydrological patterns of the Amazon River mainstream. In this context, we analyzed five sediment cores taken in two floodplain systems situated in the lower Amazon River, to investigate sediment accumulation patterns during the Holocene. Our records show abrupt fluctuations in sedimentation rates in lakes that can reach more than 2 cm/yr during some periods. We find that in all cores, sediment stratigraphy is characterized by packages of sediments of uniform age, which are typically 10-80 cm thick and present a variegated color. The C-14 age of the upper package is about 2700 cal yr BP. During this abrupt event, sediment accumulation rates in floodplain lakes can be at least 200 times higher than those of "normal" periods. This sedimentation event is interpreted as being the consequence of one or several successive extreme floods. The 2700 cal yr BP event has been also observed in other sites in South America and other regions in the world, although different impacts can be observed in each system. This event probably corresponds to a conjunction of favorable conditions for extreme Amazon discharge associated with the Middle to Late Holocene increase of austral summer insolation and shifts of the Intertropical Convergence Zone (ITCZ) from northern to southern positions. In this context, a marked negative peak in solar irradiance at 2700 cal yrs BP seems to have provoked cooling on the continents and a southward shift of the ITCZ associated with a probable reduction in the Atlantic Meridian Overturning Circulation. specialized Paleohydrology Abrupt event Climate extreme 2700 Before present Floodplain sedimentation Amazon basin AMAZONE BASSIN BRESIL PEROU 062 064 032 021 415 SI 175-182 2014 0031-0182 https://www.documentation.ird.fr/hor/fdi:010063601 10.1016/j.palaeo.2014.07.037 0031-0182 [F B010063601] https://www.documentation.ird.fr/hor/fdi:010063601 https://www.documentation.ird.fr/intranet/publi/2015/01/010063601.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-02-02 2017-08-23 fdi:010063601 fre