"Estudos geomorfológicos no litoral do Pará: setores de Bragança, Quatipurú e Salinas"

Abstract

The coastal regions are subjected to the interaction of extremely dynamic continental, marine and atmospheric processes. The present work is a contribution for a better understanding of the geomorphological processes of the Para coast using, as depositional indicators, the granulometry and exoscopy of quartz grains from beaches, dunes and estuaries, aiming to obtain new data and establish the comparison/distinction with other coastal areas of the state and the tropical world. The samples were collected in three main sectors of the Para coast (Quatipuru, Bragança, and Atalaia), submitted to particle size analysis (five sieve joqo), prepared for examination under binocular magnification, and later morphometric analysis with MPEG's Scanning Electron Microscope (SEM). The sands on the riverbank of the Campinho River (Quatipuru) and the beaches of Ajuruteua (Bragança) and Atalaia (Salinas) are very fine to fine, but their degrees of roundness are variable (highest in the dunes, next in the beaches, and third in the riverbank), i.e., the grains are mostly spherical, from rounded to rounded, going up to grains with rounded angles or even sub-angular. Thus, the conditions of use vary from one location to another, which is common in coastal areas. As for the textures, they portray either mechanical actions (shiny and polished grains from water action, shock marks, conchoidal fractures, and matted surface from wind action) or chemical alteration (dissolution, irregular and matted surface from weathering ...). The results obtained are preliminary and further studies should be carried out in the next 12 months to better understand these deposits whose understanding is determined both by the intensity of the geomorphological processes operating there and by the duration of their actions.