Paleohydrological changes, chronology of events and sediment dynamics in the quaternary of the Pantanal Wetland

Abstract

Late Pleistocene to Holocene paleo-hydrologic changes are recorded in the landscape and sedimentary record of the Pantanal wetlands, central-west Brazil. Environmental changes are mainly controlled by climatic events that took place since the aridity during the Last Glacial Maximum to more humid conditions prevailing during the Holocene and by structural factors related to the tectonic regime that operates in the sedimentary basin. Although allogenic factors related to climate and neotectonics strongly control the morphological evolution and landforms, many changes in the physical properties of sediments and sites of deposition have resulted from autogenic fluvial processes, particularly those related to avulsive river systems. In many important rivers of Pantanal fluvial plain, modern shifts in the fluvial channels have been causing great consternation of the local population. In this context, the main objectives of this project are the recognition of paleodrainage patterns, the reconstruction of Quaternary geologic and climatic events, the understanding of the hydro-sedimentary dynamics and evidences of paleohydrological changes and the establishment of relationships between allogenic and autogenic factors in the depositional setting. Many methods and techniques will be used to achieve these objectives, such as interpretation of orbital data (sattelite images and SRTM), data bank organized and processed with GIS, subsurface investigation using ground penetrating radar (GPR), surface and subsurface sampling (vibrocoring and percussion devices), facies analysis in outcrops and cores, granulometric analysis, absolute dating using Carbon-14 and optically stimulated luminescence methods, analysis of proxy data (sponge spicules , phytoliths and palynomorfs), paleopedology investigation in river terraces, hydro-sedimentary surveys with acoustic Doppler current profiler (ADCP). The available information will be integrated in order to understand the role of alogenic and autogenic factors, to define the chronology of landforms and its sedimentary deposits, and to establish the succession of geologic events that occurred in the Pantanal since the late Pleistocene. (AU)