Recent geomorphological changes in the Paraiba do Sul delta, South America East Coast

Abstract

The Paraiba do Sul River delta, a South America east coast system, presents deposits recording complex sedimentary dynamics in the deltaic plain during the Little Ice Age (LIA). The use of optically stimulated luminescence (OSL) dating, sediment grain-size characterization, and morpho-chronological analysis showed that from ∼450 to 100years (LIA period), both in lower to upper deltaic plain, remodeling occurred in conjunction with the coastline regression. The freshwater and sediment influx increases due to the moisture enhancements during the LIA resulted in the intensification of the fluvial dynamic, channel downcutting on the marine terrace, and sedimentary environments remodeling. Further, the base-level changes occasioned by the coastline regression strengthen the geomorphological dynamics associated with the recent changes in the Paraiba do Sul delta. Currently, the coastal erosion problem found in the area seems to reflect the coupling between climate dynamic (rainfall rates decrease) and multiple-scale anthropic intervention. Results show a high sensitivity of humid tropical deltaic systems to short-time climate events, further contribute to broadening discussions on the complexity of this delta system’s morphosedimentary evolution during the Late Holocene.