Sedimentation and Coastal Geochemistry on a Brazilian Oceanic Island

This book focuses primarily on the spatio-temporal study of the sedimentary, geochemical and morphological aspects of a sheltered coastal environment on an oceanic island. The research site is the Sueste Environmental System (4 degreesS/32 degreesW), located in the Mar de Fora, on the southern coast of the Fernando de Noronha Archipelago, in the south-equatorial Atlantic. The seasonal study conducted quarterly in 2010-11 indicated a textural and compositional homogeneity of the sediments, in general, moderately selected bioclastic fine sands, composed of mollusc/coral fragments and with low organic content (C -19.00/00PDB). Although seasonal morphology and geochemistry indicated spatial and temporal differences between sediments in the western and eastern portions of Sueste Beach, as well as in each sedimentary subenvironment studied: bay, beach, dune, lagoon, and mangrove. Finally, the beach profiles reveal a seasonal pattern of erosion and deposition due to regional oceanographic-climatic conditions and local morphodynamic factors. These transects also indicate the ongoing silting process in the Sueste mangrove and lagoon.