PALEOENVIRONMENTAL EVOLUTION OF THE ITARARÉ GROUP (PARANÁ BASIN) IN THE REGIONS OF SALTO AND ITU, EAST OF SÃO PAULO STATE, BRAZIL

Abstract

Itarare Group represents the glacial record of Gondwana Continent in the intracratonic Parana Basin, encompassing regions of Southern Brazil, Eastern Paraguay, Northeast Argentina and Northern Paraguay. Itarare Group is the thickest sedimentary package of Parana Basin, and was deposited over 36 million years during the end of the Carboniferous and the beginning of the Permian. However, in relation to its paleoenvironmental evolution, it is generally understood that more research is necessary, in order to better understand the genesis of the Itarare Group in different places. The present work entailed mapping facies associations for the Itarare Group in the city of Salto, in Sao Paulo State, by identifying and classifying sedimentary facies that, in turn, were utilized to develop a paleoenvironmental evolution model. This model was based on geological mapping carried out over 125 km². Petrological and petrographic descriptions of 32 outcrops of Itarare Group also were studied. These results were compared with subsurface data obtained by Sistema de Informacoes de Aguas Subterrâneas, Servicos Geologicos do Brasil (SIAGAS-CPRM; System Water Information Groundwater, Geological Survey of Brazil). Through lithofacies and petrographic analyses and making a comparison between five column sections, surface and subsurface data, a stratigraphic correlation model was established for the region. Through this model was possible to identify four facies associations, which, together, indicate how the paleoenvironmental evolution of the region occurred. The first three associations (A, B, C) were interpreted as being formed in subaqueous environment, being related to sandy lobe systems, followed by the last association (D), pertaining to a fluvial system. doi: 10.12957/jse.2016.21956