The influence of cenozoic magmatism on drainage rearrangement processes of the northeast sector of the Borborema Highlands, northeastern Brazil

Abstract

The diversity of structures and tectonic regimes in the Borborema Province caused the various morphostructural compartments to follow different evolutionary pathways throughout and after the fragmentation of Gondwana. In the northern Borborema Highlands, post-rift evolution occurred in a differentiated way, and the present study aims to understand how this occurred. For this, a set of morphological (geomorphological mapping, mapping of drainage anomalies, and extraction of relief lineaments) and morphometrics indexes (hypsometric curves, Basin Asymmetry Factor, Hack Index, Concavity Index, and χ Index) have been applied to drainage watersheds and low-order channels. The results obtained allowed us to propose a post-rift evolutionary model. To the north, the Highlands presents a recent divide resulting from a series of Cenozoic tectonomagmatic reactivations that promoted river rearrangement processes, such as drainage direction reversal and relief inversion—the current conditions of semiaridity and the absence of epigeny cause this drainage divide to remain stationary. The results diverge from the idea that only high relief margins were subject to greater tectonic control. Despite its modest altitudes, the transforming equatorial margin of Northeastern Brazil exhibits a significant recurrence of morphotectonic reactivation events, operating at different space-time scales. The area is also one of the sectors of the Brazilian passive margin with the highest record of modern seismicity.