WAVE ENERGY, SEDIMENT SUPPLY, AND SEA-LEVEL FALL: LATE HOLOCENE BASIN INFILLING IN SOUTHERN BRAZIL

Coastal sedimentation is driven by a combination of wave and tidal energy, sediment supply, and relative sea-level change. During the Holocene, these factors have combined to fill coastal embayments along the headland-dominated coast of Santa Catarina, Brazil. Here, three partially filled basins exhibit marked variability in their sediment sources, wave exposure and resulting stratigraphy and beach morphology. Hydrodynamic modeling highlights the primary roles of sediment supply and wave energy in producing three vastly different basin-fill sequences. The lack of a river source to the Pinheira Strandplain results in a bayfill sequence dominated by shelf-derived sand. Along the open coast of Navegantes, high wave energy removes fine sediments derived from the Itajaí-Açu rivers, producing a sand-dominated sequence. At Tijucas, fed by the much smaller Tijucas River, fronting headlands minimize wave energy, allowing for the accumulation of fluid mud in the shoreface. The result is a basin-fill sequence larger than that at Navegantes, but dominated entirely by mud.