Caracterização geológica e topografia espeleológica da Gruta do Castelo, Vale do Pati, Chapada Diamantina (Ba).

Abstract

The Castelo cave is an underground natural cavity developed in the sandstones of the Tombador Formation, in the Pati Valley region, geographic center of the Chapada Diamantina National Park, located in the central western part of the state of Bahia. This work involved the speleological topography and geological characterization of the lithology, structure and speleothems in order to understand the conditioning factors of its speleogenesis,and recommend actions to preserve its natural attributes. The methodological procedures included bibliographic review, research license application to the ICM-Bio, geological mapping, speleological topographic survey, structural analysis, petrographic analysis, speleothem x-ray analysis, sketching and photographic record. The lithological factors that contributed to the development of the cave were the framework composition and the percentage of rock matrix, petrographically classified as feldspar graywacke. Riedel fracture planes and sedimentary bed plans are the structural factors that favored cave formation. The origin of the silicate minerals identified in the speleothem samples is related to the incongruent dissolution reactions of the matrix and the more easily weathered rock minerals, while sulfate and phosphate minerals may be related to the mechanisms of water circulation in the underground system and reaction with guano deposits, which are easily identified in the cavity floor.