Holocene Coastal Evolution and Facies Model of the Bragança Macrotidal Flat on the Amazon Mangrove Coast, Northern Brazil

The Bragança coastal plain is a large back-barrier, macrotidal flat located in Northern Brazil. The plain is part of the largest mangrove system in the world, with approximately 8,900 km². Data derived from surface sediment samples, vibra- and percussion-cores, radiocarbon dating, and pollen analysis, allowed for a detailed stratigraphic interpretation along a 25 km long cross-normal profile and the reconstruction of paleo-environmental changes in the mangrove plain. On the basis of lithology, sedimentary structures, texture, color, elevation and bounding surfaces, ten sedimentary facies were identified. Coastal evolution during the last 5100 ¹⁴C yr B.P. has been apparently modulated by small scale subsidence events, with the onset of three phases of barrier development. Old mangrove deposits have apparently been deposited around the barriers with ages from 5115 ¹⁴C yr BP to 3412 ¹⁴C yr BP. After 2100 14C yr B.P., with the development of the last barrier island, about 20 km of mangrove progradation occurred inside the estuary.