Morphoestructural conditioning of Pedra da Andorinha Inselberg, northern Sertão of Ceará, Brazil

Abstract

The Morphoestructural conditioning of Pedra da Andorinha inselberg was investigated through regional lithostructural data and photointerpretation of local fracture arrangement from aerophotogrammetry products (orthomosaic and DEM) acquired with drone (UAV). Geomorphological aspects of a bornhardt, associated with several epigenic forms, supported by isotropic sienogranitic lithology, with grannular phaneritic texture, were verified. The structural mapping identified 13.698 fractures, with main direction to N10W, willing in an arrangement associated with topographical disparities of the study area. Relief portions with fractures high concentrations correspond to lowered areas, while fractures low concentrations were verified in elevated areas. In this way, it was noted that fractures density conditioned Inselberg's evolution, allowing that differential weathering was intensified in more deformed portions of the terrain. Residual reliefs found in the study area were exhumed by erosive processes, forming cores of greater resistance to meteorization. Consequently, Pedra da Andorinha Inselberg morphology and concomitant planing of surroundings areas, were subordinated to a structural control, whose dissection degree is controlled by fractures density.