Inlet migration during the turning point between transgressive and regressive stages at the Guaratuba Holocene barrier, Parana-Southern Brazil

This paper analyzes the sedimentary record of a paleo-inlet that evolved in association with a coastal barrier, using data that provides a high-resolution stratigraphy. During the evolution of the Guaratuba Holocene barrier, autogenic factors associated with the paleo-estuary dynamics compete with allogenic factors of RSL (Relative Sea Level) variation and the influence of climate on sediment input. The integration of geological mapping, vibrocore, GPR (Ground Penetrating Radar), and radiocarbon dating techniques allowed for recognizing of a paleoinlet migrating east-southeast during the turning point between the transgressive and regressive stages, cyclically affected by episodes of aggradation and reversal in the direction of lateral migration. This dynamic, conditioned by shadow zones of bedrock elevations and the littoral drift of sediments, modifies the stratigraphy and the barrier's depositional architecture, defining diachronous surfaces and lateral variations in the stratigraphic stacking. These features exemplify how barrier-inlet systems are affected by the combination of high frequency, climate-defined events and local coastal processes during their evolution.