Uso de traçadores geoquímicos para caracterização dos sedimentos fluviais modernos - na fração areia - na região do médio Tocantins

Abstract

Understanding that river systems are sensitive and reporting climate change has made sedimentological studies geomorphological and chronological in the Amazon, what became the basis for geochemical studies from the analysis of larger elements to characterize the provenance of modern river sed iments in the region midle Tocantins river. The main objective of this work is to use geochemical tracers from the analysis of larger elements to characterize the modern river sediments in the region midle Tocantins river, in order to interpret the sedimentation and deposition processes. A particle size study was applied to help understand possible correlations between the particle size and sediment geochemistry in the sand fraction. High resolution scanning X-ray fluorescence (XRF) analyzes on sediments were performed to provide data on the elemental ratios Ti/Ca, Fe/Ca, Si/K, Fe/Si and Fe/k defined as proxies for the characterization of the sediments river and Interpreting the interference or not of weathering, caused by Fe concentration in the samples as a means of characterizing the modern sediments that make up the Tocantins. The main control factor of the different sedimentation sources is the weathering process associated with the lithological variation of the rocks and geological anomalies that are drained by the watershed. Results of analysis by XRF of elementar y ratios, analysis of elementary ratios made it possible to distinguish the sediments that make up the river bank and channel and, consequently, to distinguis h between geochemical signatures, which allowed us to understand that they drain areas composed of distinct lithologies and Thus, it allowed the interpretation of deposition and sedimentation processes for them.