1. Neodymium and Strontium isotopes as source indicators for terrigenous sediments deposited in NE Brazil
- Author
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Leopoldo D. Pena and Itxaso Ruiz
- Subjects
geography ,geography.geographical_feature_category ,Terrigenous sediment ,Amazon rainforest ,Drainage basin ,Geology ,Last Glacial Maximum ,Isotopes of strontium ,Geochemistry and Petrology ,Glacial period ,Stadial ,Geomorphology ,Holocene - Abstract
espanolEste estudio investiga el origen sedimentario de los materiales depositados por el rio Amazonas durante los ultimos 30 kyr BP y reconstruye el patron de precipitacion del area fuente. Para ello, se han utilizado quince muestras de un registro sedimentario marino ubicado en el margen de la Guayana Francesa y se han analizado los isotopos de Neodimio (Nd) y de Estroncio (Sr). Los resultados (Sr: 0.71385±0.00166; eNd: -11.67±0.55) sugieren que la zona del Amazonas occidental es la fuente principal del material terrigeno, y apuntan a la cuenca del rio Solimoes como el origen mas probable. Asi mismo, el analisis paleoclimatico de la zona refuerza esta conclusion, exhibiendo condiciones continentales humedas para los Heinrich Stadials 1 y 2 en comparacion con el Ultimo Maximo Glacial, asi como para el Ultimo Maximo Glacial en comparacion con el Holoceno temprano EnglishThis 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; eNd: -11.67±0.55) suggest that the western Amazon basin catchment area is the main source of the terrigenous material, and point to the Solimoes 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.
- Published
- 2018