Geologia da área compreendida entre a Gruta dos Brejões e a Serra da Babilônia, município do Morro do Chapéu, Bahia

Abstract

This work is the result of geological mapping on the scale 1:25,000 comprising an area of 220 km 2 , located in the Chapada Diamantina northwest of Morro do Chapeu town, in Bahia state. The stratigraphy of this area is represented, from bottom to top by Morro do Chapeu Formation, of the Chapada Diamantina Group (constituted by quartzites, representing 27% of the area); by Bebedouro Formation (formated by metassiltites, tills, flints, and arkosean quartzites, comprising 18% of the area); by Bambui Group (indicated by calcilutite, dololutitc, dolomite, marldolorrudites, and intraformational breccia, corresponding to 53% of the area); by Caatinga Formation (represented by monomitic breccia, sandstone, petromitic conglomerate, and limestone, representing 0,6% of the area), and unconsolidated sediments comprising 1,4% of the total area. The quartzites of the Morro do Chapeu Formation show transgressive-regressive alternations (with marine-coastal sediments), stood by presence of feldspar, possibiliting its division in two facies. The Bebedouro Formation was separated in two parts: inferior and superior members. Bambui Group, for its characteristics: color, texture, thickness of the layer, and sheets, may be divided into facies and subfacies, and it may be still made on type section to the area, since the Serra da Babilonia until extreme western part of the region.