Reconstituição Paleogeomorfológica do Maciço do Itaóca e depósitos sedimentares do seu entorno, Campos dos Goytacazes (RJ)

Abstract

The Itaóca Massif consists of a sequence of domes developed from a granite monolith, delimited by fractures / diaclases, and resistant to differential erosion that reaches at the top the altitude of 414 meters. Among the main forms of granite relief are the cupuliforms and bell-shaped domes, crags, isolated boulders and the flattened rock surfaces that correspond to the slabs leveled at low altitude. The surroundings of the Itaóca Massif are formed by soft hills of the planing surface of the east coast of the State of Rio de Janeiro, isolated trays and the fluvial-marine plains of the Baixada Campista. The proximity and the geographic distribution of the trays constituted by deposits of the Barreiras Formation suggests the existence of an assumed basal surface associated to the lower levels developed in the Itaóca Massif. The general planing in granitic terrain, and partial removal of the regolith under different morphoclimatic domains from the present, may have initially provided a predepositional plan constituted by mosaic of slabs that was covered during the Miocene by the sediments of the Barreiras Formation. Through the geomorphological mapping, the characterization of laboratory clasts, the use of tools in the identification of palynomorphs, recognition of minerals presumed by fluorescence (XRF), and the geographic distribution of Barreiras Formation deposits, the paper tries to present a hypothesis, with the established premises, of the possible evolutionary sequence of the Itaóca Massif and surroundings under different morphoclimatic domains during the Cenozoic in Southeastern Brazil. The Itaóca Massif apparently conserved on its eastern and southern border the remaining Barreiras Formation, which were later covered by eluvial-colluvial deposits from the areas around the granite massif