Evolução geomorfológica do inselberg Pedra da Andorinha, Taperuaba, Sobral, Brasil

Abstract

The geomorphological evolution of the granitic-migmatitic terrains that delineate the Inselberg Pedra da Andorinha was investigated through geological, geomorphological, morphotectonic and aerial photogrammetry data, based osn theory of planation climatic. The information concerning lithologic properties and tectonic events were allied to the photointerpretation of the local structural weave through the elaboration of ortomosaico and MDE, produced from a Unmanned Aerial Vehicle (UAV). Geomorphological aspects of a bornhardt were identified, with isotropic sienogranitic, phaneritic and faciological uniformity. Structural mapping identified 13,698 fractures, with main trend at N10W. This direction controls the main geomorphological features, where high discontinuity densities correspond to recessed areas, while low concentrations are observed in the raised portions. It was verified that epigenic intemperic dynamics was intensified in the portions susceptible from a differential weathering, with intensity directly proportional to fracture density. The residual reliefs of this process were exhumed as more resistant cores from the laminar erosion. Therefore, the morphology of the Swallow Stone and the concomitant planing of areas in its surroundings are subordinated to a structural control, whose degree of dissection is controlled by the density of fractures.