Morphostructural aspects of the sandstone karst in Northeastern Brazil: Example from Serra da Capivara – PI

Abstract

This work analyses morphostructural aspects and their influence on the development of the karst reliefof Serra da Capivara (State of Piauí, northeastern Brazil). For this purpose, structural data derived from lineamentextraction, sedimentary bed geometry, karstification degree of the layer, and analysis of the karst morphologywere performed. Structural lineament data showed a NE-SW orientation trend, coinciding with the orientationof the Transbrasiliano Lineament. The reactivation of the brittle structures can be related to the orientation, scarpretreat, direction, and incision of the main valleys. From the analysis of the fracture array (NE-SW) and beddingplanes, we suggest that the fracture connectivity of these structures resulted in conduit formation, which evolvedto form subterranean galleries. Thus, the expansion of the karst system led to the formation of valleys, which aresituated in higher deformed zones, such as fold hinges. These valleys currently constitute the most advancedstage of karstification, with the development of the tributary drainages as the most recent stage. The structuraldirections show a NE-SW trend, represented by larger valleys, and subordinated to this, an NW-SE trend, whereheadwaters of low-order channels are located.