Estudo da evolução da paisagem atual da Serra do Tepequém, município de Amajarí - Roraima a partir da análise de depósitos coluvionares

Abstract

This research aims to understand the evolution of the current landscape mountain Tepequém, Amajarí - RR, from the colluvial deposits analysis. Field activities were carried out in order to characterize the deposition environments of colluvial sediments and sample collection. In laboratory was carried out treatment techniques and manipulation of digital images to create thematic maps highlighting altimetry morphometric parameters, slope and orientation of the slopes, as well as topographic profiles and spatial distribution of colluvial deposits. The colluvial sediments were subjected to particle size analysis, mineralogical, morphological and chemical by EDS. The top of the mountain presents altimetric variations caused by the existence of lowland areas, hills and hills, steep slopes, representing the steepest slopes of the mountain. Environments conducive to deposition of colluvial sediments, is the base of hills and hills, forming elongated or interception fringes. The colluvial sediments consist predominantly of sandy fraction and siltic sand, with average diameter, are very poorly selected, with a degree of positive skewness very positive, and kurtosis values platykurtic the leptokurtic. The grains of colluvial sediments have subangular morphology, still containing angular grains, subrounded and rounded. Exhibit abrasion surface cavities and cracks due to mechanical action. It has been found in the chemical analysis, the composition predominantly of SiO2 and less intense Fe2O3 and K2O plus MgO and TiO2. These data show the transport mass movement by crawling material detrital the short distance between the source area and deposition.