Seções litoestratigráficas e petrografia sedimentar das fácies dos ritmitos areno-pelíticos do cerro da angélica na pedreira Bella Gres, Caçapava do Sul, RS

Abstract

The slopes of the deactivated Bella Gres quarry, where clay extraction for ceramic production was carried out in the early 1980's, is situated near the northern flank of Cerro da Angélica, southeast of the urban center of Caçapava do Sul. Where, it is possible to observe excellent exposure of ritmites arenitic-pelitic and the structures that characterize the Bom Jardim Group's Mangueirão Formation, in the central portion of the Camaquã Basin. The main objective of this research was to carry out the survey of lithostratigraphic sections on a detailed scale through the macroscopic and microscopic description of the facies observed on the slopes of the quarry. In this way, it was possible to identify the presence of sandstones of very fine to medium granulometry and fine sediments, both with internal structures like ripples and planeparallel stratification. Based on this survey, it was possible to define the stacking and the way in which these facies are distributed in space, thus characterizing the periods of acceleration and deceleration of the depositional system. Therefore, it was observed that the facies are repeated throughout the section, with variation of the thickness of each package. Thus, based on these data, it can be mentioned that the facies described in this work correspond to the turbidite sequence of Bouma (1962).