Fácies e estratigrafia do canal de maré do Porto da Barra Grande, Icapuí - CE

Abstract

The Icapuí coastal plain is composed by overlapping sea terraces, coastal strands, lagoons and wind deposits, bordered in the south by the cliffs of Barreiras Formation, and is morphologically cut by tidal channels where is located the Barra Grande Port. In general, the area presents regressive features during the Upper Holocene. However, tidal flats and channels can be formed under completely different conditions, providing important information about the evolution of this depositional environment. In order to characterize the Barra Grande Port tidal channel in a faciological and stratigraphical aspects, highlight the relationship between factories and understand how the short and long term changes occur in the region, it were stablished 16 facies grouped into three sedimentation stages (lower, intermediate and upper portions) based on six cores sampled in the area of study. The lower portion is basically composed of mud and fine sand. The intermediate portion is composed of medium to coarse sediments, high amount of shells and gravels, high ZTR index, moderate CaCO3 content and low amount of organic matter. The upper portion is composed of fine to medium sediments, with roots and preserved shells, low ZTR index, CaCO3 and organic matter contents. The sedimentary succession was interpreted as lagoon sediments, followed by transgressive and regressive deposits.