Geological Field Guide of Montes Claros Karst, Minas Gerais

Abstract

The Montes Claros Karst is located on the eastern margin of the Bambuí Basin, one of the covers of the São Francisco Craton affected by the Brasiliano Event, which deformed the limestones of the Lagoa do Jacaré Formation, creating a westward folding system and a pair of fractures F1 (NNE-SSW) and F2 (WNW-ESE). These structures control the circulation of water in the limestone massifs, leading to the development of the Montes Claros karst. The main features of the karst landscape are caves, valleys, dolines and limestone massifs. The caves are the best place to observe the main sedimentary facies of the limestones of the Lagoa do Jacaré Formation, as well as sedimentary and deformational structures. The main controls of the cave conduits are the F1 and F2 fractures. These are the same directions described on a regional and local scale, which shows us that the structural control of the exocarst is the same as that of the endocarst. This geological field guide shows in a didactic way the main facies and sedimentary structures of the limestone of the Lagoa do Jacaré Formation, the deformational structures that favoured the karst formation and the typical karst morphologies in limestone rocks.