Isótopos de Neodimio y Estroncio como indicadores del área fuente del material terrígeno depositado en el NE de Brasil

Abstract

This study investigates the sedimentary origin of materials deposited by the Amazon River over the last 30 kyr BP and reconstructs the precipitation pattern of the source area at the time of the erosion. For this purpose, fifteen samples of a down-core sediment record from the French Guiana margin have been used to analyse neodymium (Nd) and strontium (Sr) isotope ratios. The sample results (Sr: 0.71385±0.00166; e Nd :-11.67±0.55) suggest that the western Amazon basin catchment area is the main source of the terrigenous material, and point to the Solimões river basin as the most probable origin. This study also discusses the strong coherence between the registered millennial events and the atmospheric settings of the region, which indicate humid land conditions for the Heinrich Stadials 1 and 2 compared to the Last Glacial Maximum, and during the Last Glacial Maximum compared to the early Holocene. © 2018, Instituto Geologico y Minero de Espana. All rights reserved.