Numerical Modeling of Weathering, Erosion, Sedimentation, and Uplift in a Triple Junction Divergent Margin

Abstract

The majority of numerical models of landscape evolution in divergent margins are focused on the simulation of margins with simplified lithological control on landscape erosion. However, this approach is insufficient to study the evolution of margins where chemical weathering is an important element increasing rock resistance to physical erosion. One example of this margin is the Borborema Province, northeastern Brazil, where postrift marine sediments are now preserved at elevations ∼700–800 m in up to 1‐km‐high plateaus capped by duricrust layers. The landscape evolution of these uplifted sedimentary basins still eludes explanation. Here we use numerical models that couple weathering, erosion, sedimentation, sea level changes, flexural isostasy, and thermal effects due to lithospheric stretching to simulate the tectonosedimentary evolution of the Borborema Province since the onset of continental stretching during the Lower Cretaceous. These numerical experiments reveal that nearly 70% of the postrift regional uplift observed in the Borborema Province can be explained by differential denudation of the continent and flexural rebound of the lithosphere. The remaining ∼250 m of uplift can be explained by thermal uplift induced by partial erosion of the base of the continental lithosphere under the Borborema Province due to edge‐driven convection, in accordance with the anomalously thin continental lithosphere observed under the Borborema Province. Additionally, the numerical results can explain the regional pattern of fission track ages by the combined effect of differential denudation and flexural rebound in this geometrically complex margin.

New detrital petrographic and thermochronologic constraints on the Late Cretaceous–Neogene erosional history of the equatorial margin of Brazil: Implications for the surface evolution of a complex rift margin

“…According to Pessoa Neto (2003), such a recent stage of denudation would explain the siliciclastic influx observed in the Neogene sediments of the offshore Potiguar Basin (Figure 1). However, these interpretations have been recently challenged based on morpho‐stratigraphic data indicating less than 600 m of post‐Cenomanian surface uplift and mean erosion rates of 1 m/Ma (Peulvast & Bétard, 2021; Sacek et al, 2019). Our detrital AFT data do not detect significant Neogene detrital age populations (Figure 11), indicating that during this time, in the drainage areas of the basins of this study, vertical erosion must have been less than 1 km.…”

“…To explain the Late Cretaceous exhumation of the Borborema Province, Morais Neto et al (2009) proposed thermal-isostatic uplift and magmatic underplating. Sacek et al (2019) explained 70% of the post-rift regional uplift as resulting from the combined effect of differential denudation and flexural rebound of the lithosphere and the remaining 30% as thermal uplift induced by partial erosion of the base of the continental lithosphere underneath the Borborema Province. Our data, rather than revealing the geodynamic scenarios governing post-rift tectonic, provide some constraints on the maximum amount of exhumation related to these events along the equatorial margin of Brazil and inform on the dynamics of the landscape evolution.…”

“…This study contributes with new constraints on the erosional history of the equatorial margin of Brazil. This is a cratonic area that exposes crystalline basement and siliciclastic sedimentary rocks and that underwent a complex, still debated, Late Cretaceous and Cenozoic surface evolution (Garcia et al, 2019; Japsen et al, 2012; Morais Neto et al, 2005–2006, 2008, 2009, 2010, 2012; Morais Neto & Vasconcelos, 2010; Peulvast & Bétard, 2021; Sacek et al, 2019). The Atlantic margin of Brazil evolved since rifting between the African and South American plates in the Late Jurassic–Early Cretaceous.…”

Eroded topography in Proterozoic Basement: the case of Capiá river watershed, Semi‐arid Northeastern Brazil

“…The genesis of these surfaces has been at the core of the debate in Geomorphology, and several conceptual models have been enlisted to elucidate their origin (e.g., ORME, 2013). The morphogenesis of these surfaces has traditionally been described as the end product of prolonged denudation cycles, in contrast to more recent studies that highlight the role of geodynamic mechanisms in the conformation of relief on a regional scale, especially when it comes to the post-rift evolution of continental margins and hinterlands (CORRÊA; MONTEIRO, 2021;SACEK et al, 2019). Likewise, the problem of planation surfaces has been put under the prism of post-orogenic landscape evolution (e.g., PEULVAST; CLAUDINO-SALES, 2002; BONNET et al, 2000) and lithosphere and mantle deformations (e.g., GUILLOCHEAU et al 2018).…”

“…On the other hand, emerging approaches are already available. Sacek et al (2019), through numerical modeling, geochronological and stratigraphic data analysis, state that approximately 70% of the topography of Borborema Province can be explained by a flexural rebound and differential erosion mechanisms. The rest, still according to the authors, would be controlled by the thermal uplift process in response to the erosion of the continental lithosphere base, caused by convection at the boundary between the continental and oceanic crust.…”