GEOMORPHOLOGICAL AND SEDIMENTARY MAPPING OF PALEO-LINES OF COAST IN THE CONTINENTAL PLATFORM SOUTH OF ALAGOAS

Abstract

The objective of this study is to investigate the paleo coastlines present in the southern continental shelf of Alagoas. Due to the low contribution of continental sediments contributed by the rivers in this continental shelf, the bottom features formed in the last cycle of sea level variation, did not allow that they were completely buried. Thus, to investigate these features, a bathymetric model was elaborated from the Border Sheets of the Hydrographic and Navigation Department (DHN) of the Brazilian Navy. Subsequently, the main anomalies in the relief (elevation or depression) were identified and mapped. The main features identified in the continental shelf of Alagoas were three sets of submerged reefs aligned and parallel to the coastline were identified at -25m, -15m and -5m and the paleo valleys of Maceió, Jequiá-Jacarecica and Coruripe that were evident in the bathymetric model. We conclude that the origin of the paleo valleys is related to the last glacial maximum when the rivers excavated the continental shelf and the formation of the reefs indicate the periods of stabilization of the sea level that correspond to paleo coastlines.

Keywords

• Sea Level
• Reefs
• Marine Sediments;
• Incised Valleys;
• Coastal Zone.