During late Pleistocene -Holocene climatic changes, the Portuguesa river watershed, Central West Plains, Venezuela, experienced environmental and hydrologic changes. The present study research is based in a morpho-sedimentary analysis and is sustained by 21 optically stimulated luminescence (OSL) datings of fluvial and eolic deposits. Recent sediments are dominated by medium and coarse sands, while the oldest deposits are dominated by medium to coarse silt. The dominant mineralogy for both deposits is quartz and kaolinite. The studied lithofacies reveal channel deposits or meander bars (AF1) and sand bars (AF2) associated with small deltas. The proximal morphological deposits indicate the development of mega-fans and fluvial terraces and the distal sediments developed channel and inundation plain deposits. The ages of the fluvial deposits are between 19000 ±1570 and 15200 ±2300ka, suggesting that the construction of the megafans started at least during the last glacial maximum (LGM), followed by cutting, paleomeander and terrace formation during the early and late Holocene (10990 ±2850 to 3850 ±840ka). The ages of the eolic deposits (14720 ±1800 y 4510 ±860ka) indicate that climate conditions during the Late Glacial and the Middle Holocene still were semiarid to sub humid , or close to present climatic conditions.
|Translated title of the contribution||Paleo-environmental changes during the late pleistocene -holocene in the portuguesa river watershed, central west plains, Venezuela|
|Number of pages||9|
|State||Published - Oct 1 2013|