Implications of drainage rearrangement for passive margin escarpment evolution in southern Brazil Michael Vinicius de Sordi a, ⁎, André Augusto Rodrigues Salgado a , Lionel Siame b , Didier Bourlès b , Julio Cesar Paisani c , Laëtitia Léanni b , Régis Braucher b , Edivando Vítor do Couto d , ASTER Team (Georges Aumaître and Karim Keddadouche) b a Geography Department of Minas Gerais Federal University, 6.627 Antônio Carlos Avenue, Pampulha, CEP 31270-901 Belo Horizonte, MG, Brazil b Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France c State University of Western Paraná, Francisco Beltrão Campus, 1200 Maringá Street, Francisco Beltrão, PR, Brazil d Environmental Academic Department of Paraná Federal Technological University, 1233 Via Rosalina Maria dos Santos, CEP, 87301-899 Campo Mourão, PR, Brazil abstract article info Article history: Received 16 September 2017 Received in revised form 8 January 2018 Accepted 8 January 2018 Available online 31 January 2018 Although several authors have pointed out the importance of earth surface process to passive margin escarpments relief evolution and even drainage rearrangements, the dynamics of a consolidated capture area (after a drainage network erodes the escarpment, as the one from the Itajaí-Açu River) remain poorly under- stood. Here, results are presented from radar elevation and aerial imagery data coupled with in-situ-produced 10 Be concentrations measured in sand-sized river-born sediments from the Serra Geral escarpment, southern Brazil. The Studied area's relief evolution is captained by the drainage network: while the Itajaí-Açu watershed relief is the most dissected and lowest in elevation, it is significantly less dissected in the intermediate elevation Iguaçu catchment, an important Paraná River tributary. These less dissected and topographically higher areas belong to the Uruguai River catchment. These differences are conditioned by (i) different lithology compositions, structures and genesis; (ii) different morphological configurations, notably slope, range, relief; and (iii) different regional base levels. Along the Serra Geral escarpment, drainage features such as elbows, underfitted valleys, river profile anomalies, and contrasts in mapped χ-values are evidence of the rearrangement process, mainly beheading, where ocean-facing tributaries of the Itajaí-Açu River capture the inland catchments (Iguaçu and Uruguai). The 10 Be derived denudation rates reinforced such processes: while samples from the Caçador and Araucárias Plateaus yield weighted means of 3.1 ± 0.2 and 6.5 ± 0.4 m/Ma respectively, samples from along the escarpment yield a weighted mean of 46.8 ± 3.6 m/Ma, almost 8 times higher. Such significant denudation rate differences are explained by base-level control, relief characteristics, and the geology framework. The main regional morphological evolutionary mechanism is headward denudation and piracy by the Itajaí-Açu River tributaries. As the escarpment moves from east to west, Itajaí-Açu River tributaries develop, leading to regional relief lowering and area losses within the Iguaçu and Uruguai catchments. Such processes were accelerated since Itajaí-Açu tributaries reached into sedimentary and volcanic rocks. From this moment on, Serra Geral became the main hydrographic divide between the ocean- and inland facing-catchments in the area. © 2018 Elsevier B.V. All rights reserved. Keywords: Passive margin escarpment Southern Brazil Serra Geral Cosmogenic nuclide Drainage rearrangement 1. Introduction Passive margin escarpments are among the most notable landforms worldwide and their origin is associated to extensional tectonics, which results from continental plate breakup, rift opening and oceanic expansion (Summerfield, 1991; Gilchrist and Summerfield, 1994; Matmon et al., 2002). Escarpments are typical features of passive margins, separating inland plateaus from coastal plains (Seidl et al., 1996). Over the last decades, significant advances in low-temperature thermochronological (zircon and apatite fission track) and in-situ- produced cosmogenic nuclide techniques have reactivated discussions about the long-term evolution of passive margin escarpments (Seidl et al., 1996; Cockburn et al., 2000; Brown et al., 2002; Matmon et al., 2002; Persano et al., 2002; Braun and van der Beek, 2004; Vanacker et al., 2007; Roller et al., 2012; Salgado et al., 2014, 2016; Braun, 2018). Such studies have shown that after an initial phase of accelerated retreat, during the early stages of seafloor spreading, escarpments remain almost stationary, with their location being a function of the crustal structure and the distribution of the normal faults related to rifting and expansion. After stabilization, escarpments are then eroded mainly by surface processes, namely hydrographic and mass-wasting processes, in close relation to headward erosion and migration of knickpoints along river profiles. Geomorphology 306 (2018) 155–169 ⁎ Corresponding author. E-mail address: michael.sordi@gmail.com (M.V. de Sordi). https://doi.org/10.1016/j.geomorph.2018.01.007 0169-555X/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph