Planation surfaces and divide mobility in the Chapada do Araripe (NE Brazil)

Abstract

This study investigates planation surfaces and the dynamics of river divides in Northeast Brazil, with a focus on the Chapada do Araripe region. The research integrates morphometric metrics and regional geological interpretation to understand the processes that shape the evolution of the relief through the migration of divides and the interposition of planation surfaces. Geomorphometric metrics based on a digital elevation model (including TPI, Ksn, χ index, and Gilbert metrics) were applied, and three main surface levels were identified: S1 (>710 m), S2 (485–710 m), and S3 (<485 m), which reflect distinct stages of pediplanation since the Cretaceous. The analysis reveals that the preservation of these surfaces is strongly conditioned by structural, lithological, and climatic factors. Additionally, the results indicate variations in the stability of the river divides among the Parnaíba, Jaguaribe, and São Francisco basins, with a tendency toward migration on the Jaguaribe-São Francisco and São Francisco-Parnaíba divides, associated with fluvial reorganization processes. This work proposes an evolutionary model for the region's landscape, highlighting the interactions among tectonic heritage, differential erosion, and climate change over geological time.