Análise faciológica da planície de Maré de Icapuí (CE)

Abstract

This study was carried out in the tidal plain of Icapuí, in order to analyze the faciology and stratigraphy of the tidal plain during the Holocene age, its evolutionary context and its coastal dynamics. The tidal plain of the study area presents an area of approximately 12.5 km², being formed by the sand-mud deposits of Banco dos Cajuais. The work consisted of the analysis of four 2 meter pipes that were introduced in the tidal plain. The sedimentary facies of the study area were characterized by granulometry and calcium carbonate content, statistical treatment, heavy minerals, biotic components, and organic matter and organic carbon contents. The structures found in the pipes are homogeneous, some gradational and abrupt contacts, very mineral micaceous, and fragments of marine and coral organisms. Seven sedimentary facies were defined, with the sand fraction predominating in the samples, followed by mud and gravel. Statistical treatment indicated an intermediate textural maturity and an environment unbalanced energetically. The calcium carbonate content of the sediments presented average to high values, and it is distributed in the pipes in a very heterogeneous way, which arouses the curiosity in the sedimentation change of the area. The analysis of organic carbon and organic matter suggest a low energy sedimentation. The studies of the heavy minerals indicated a reworking of the sediments of the Barreiras Formation, and contribution of the weathering of rocks of the Santarém Formation. The study of the biotic components showed suspension transport in a low energy environment with rapid sedimentation of the organism. From the results, it is understood that the Icapuí tidal plain presents the expected data. However, it leaves some doubts, which suggests more studies in the area.