Sea-level rise and sediment budget controlling the evolution of a transgressive barrier in southern Brazil

This paper presents an evolutionary model for a coastal barrier in the southernmost coastal sector of Brazil during the Holocene. The dataset is based on 15-20 m drill cores and ground-penetrating radar (GPR) records. The model barrier evolution has two main steps. The first step is the transgression of the barrier controlled by sea-level rise during the Postglacial Marine Transgression, which ended at approximately 6-5 cal ka. Radiocarbon dating indicates that the coastal plain began to be flooded by lagoonal waters between ∼10 and 6.7 cal ka. The second step comprises a barrier transgression controlled by a negative sediment budget of the beach system during the last 6-5 cal ka in a period of an overall slow sea-level fall of approximately 2 m. During the second step, the transgressive barrier migrated because of coastal erosion (the negative sediment budget) and the landward transference of sand by wind and lagoonal delta washout.

► Model of a transgressive barrier evolving under a sea-level fall condition. ► Integration of litological data (drill holes) with geophysical data (GPR). ► Palynology as an element of environmental interpretation. ► Connection between barrier transgression and formation of transgressive dunes.