Caracterização geomorfológica e espeleológica das cavernas de Presidente Dutra - MA

Abstract

This study aimed to characterize the geomorphological and speleological aspects of the caves located in the municipality of Presidente Dutra-MA, addressing existing gaps in the documentation of these formations. Although some caves had been cataloged by researchers from the Foundation for the Support of Scientific and Technological Research and Development of Maranhão (FAPEMA), the available information was limited and inconsistent. Thus, this research analyzed the geomorphogenic processes responsible for the formation and evolution of these cavities, as well as identified and characterized the geology of the host rock. Silty sandstones with light to cream tones from the Grajaú Formation were identified in the Furnas caves, while sandstones with planar-parallel cross-stratifications, showing signs of oxidation and disaggregation from the Urucuia Formation, were found in the Angélica caves. The adopted methodology involved the description of geological and geomorphological features essential for the planning of prospecting and vectorization of these caves, physical topographies, and the finalization of detailed speleological maps. The study considered the structural features of the caves, their horizontal extension, geological formations, speleobiological aspects, and potential attractions for conservation and sustainable use. The caves studied in Presidente Dutra- MA revealed complex formations resulting from the combined action of physical and chemical processes. Differential erosion, favored by the presence of sandstone layers with varying resistance, was one of the main speleogenetic mechanisms, according to the model proposed by Auler and Smart (2002). In the Angélica caves, evidence of oxidation and cement dissolution between grains indicates arenization processes, highlighting the chemical activity even in non-carbonate lithologies. The geological characteristics of the Grajaú and Urucuia Formations, including the presence of silexite and carbonate facies, directly influenced the morphology of the caves, explaining the structural variation between the Furnas and Angélica systems. The produced topographic maps detail inclinations, vertical differences, and internal compartments, contributing in an unprecedented way to the speleological documentation of the region and providing a solid foundation for future studies