Neotectonics in the South American passive margin: Evidence of Late Quaternary uplifting in the northern Paraiba Basin (NE Brazil)

摘要

The relief evolution of several areas of northeastern Brazil has been increasingly related to tectonic events. This is the case for the Paraiba Basin, where an abundance of faults and folds were recorded in Neogene and even Late Pleistocene-Holocene deposits. We tested whether dome-like morphologies in the northern sector of this basin, where geological exposures are scarce, were also formed by tectonic deformation. The work combined limited geological data with qualitative and quantitative analyses of the relief applying the 1 arc-second digital elevation model provided by the Shuttle Radar Topography Mission. The geomorphic indices of basin asymmetry factor (AF), swath topographic profiles, enhanced transverse hypsometry index (THi*) and normalized river long-profiles were used for validating a neotectonic origin for the dome-like morphologies. This interpretation was also supported by other morphological evidence of the dome relief, including: recurving channels featured in radial to recurved trellis patterns; tectonically-controlled drainage sub-basins; high relative relief values related to increased fluvial incision; and anomalous river long-profiles indicative of ungraded rivers. The domic structures were attributed to fault- and fold-related strike-slip deformation during the late Quaternary. This record supports the proposal that the South American passive margin remained under tectonic stress long after the main rifting in the late Jurassic-early Cretaceous. Published by Elsevier B.V.