Geological study of sediments from the Negro and Solimões rivers<i></i>

The Amazon is the largest and most complex ecosystem on the planet, and its entire evolutionary history was influenced by the dynamics of the Amazon River System. The geomorphological features of sections of the Solimões-Amazonas River have been studied using images from remote sensors, combined with multitemporal analysis data, and part of the sedimentary deposits is confined in four tectonic depressions that occurred during the Neomiocene-Pliocene, called hemigrábens of Paraná do Ariaú (GPA), Cacau do Pereira (GCP), Cachoeira do Castanho (GCC) and Lago do Miriti (GLM). The objective of this work was to characterize 59 sediment samples from the confluence region of the Negro and Solimões Rivers, Central Amazon using the instrumental neutron activation analysis (INAA). The experimental results obtained were subjected to cluster and discriminate analysis, revealing the formation of three groups with similar chemical composition. The differences are related to the geochemical conditions inherent in the individual depositional environments.