Origin and development of a delta landscape at the mouth of the Amazon River: The Breves-Boiuçu delta – Northern Brazil

The genesis and formation of fluvial features at the mouth of the Amazon River (Northern Brazil) have been commonly associated only with changes in the mean sea level that occurred in the Quaternary. In this sense, the objective of this study was to understand the dynamics of the Breves-Boiuçu Delta and its Quaternary evolution, according to its progradation/erosion and Neotectonic controls. Structural lineaments were automatically detected using SRTM data by the SID3 software, and statically analyzed to identify the main lineament domains. In addition, drainage anomalies were mapped and the coastline changes (1986 to 2019) were evaluated using Landsat 5 and 8 satellite images. The lineament domain analysis point to the existence of a regional dextral shear zone NE-SW oriented. The ENE-WSW structures correspond to T fractures, whereas the N-S structures are dextral P, and NW-SE are sinistral faults (R’). The drainage patterns are tectonically controlled, and there is a long paleochannel between the Pará and Amazon Rivers, suggesting the existence of an ancient connection between these rivers. Finally, the changes in the coastline data indicate progradations in the delta frontal part and erosion in the distributary zone. In this context, through an evolutionary model we infer that there was a paleodelta between the Pará and Amazon rivers, which was abandoned due to river captures, resulting from the reactivation of the NE-SW dextral shear corridor and the Gurupá Arch. After the abandonment of the paleodelta, the Breves-Boiuçu Delta developed on the north of the Melgaço Bay.