Optically stimulated luminescence dating of fluvial deposits in the middle Purus river, southwest Amazonia

Abstract

The Amazon basin is the largest in the world and cradle to one of the most biodiverse ecosystems on Earth. With the growing concern of society and the scientific community about the impacts of anthropogenic factors on climate, the studies of the climate changes on thousands of years have earned prominence in last years. Is known that fluvial system dynamic is influenced by such changes, being able to present complex and variable answers. The preserved sedimentary deposits in terraces and river plains are potential records of environmental changes on scale of the watershed, its study makes possible to reconstruct past environmental condition and his impact in river dynamics. However, geochronological and sedimentological data enable to understand the evolution of the Amazonian river basin system along the Quaternary is lacking, mainly in reference to rivers that exclusively drain lowlands of central and western Amazonia. The Purus river is main representative of the Amazonian lowland rivers, which the standard feature is high sinuosity of the channel and the well-preserved terrace levels. The main aim of this research project is applying optical stimulated luminescence (OSL) dating to estimate sediment deposition age that are preserved in terrace levels and fluvial plain in the middle Purus river, southwest Amazonia. The integrated analysis of the OSL ages, geomorphological, sedimentological and geochemical data, developed in context of the research project coordinated by the advisor will allow us to elaborate a paleographic model for Purus river during the Late Quaternary. The information produced will also provide data on the answer of Amazonia lowland rivers to climate and tectonic changes and possible relations between geological history and evolution of biodiversity.