Lithological and mesoclimatic controls on denudation rates in transform margin crystalline massifs: Insights from cosmogenic 10Be and 26Al in semi-arid Brazil

The landscapes of the transform margin of semi-arid Brazil are characterized by planation surfaces dotted with varied residual reliefs. In this context, denudation rates were measured in crystalline massifs with lithological and climatic contrasts, evaluating the role of differential erosion and mesoclimatic gradients in their morphogenesis. Data from in situ produced cosmogenic nuclides ( 10 Be and 26 Al) were analyzed from 49 samples of fluvial sediments and bedrock, distributed across four massifs (Baturité, Aratanha, Maranguape, and Uruburetama) and the surrounding planation surfaces. The obtained denudation rates were integrated with morphometric, structural, and biophysical analyses at the catchment scale. Apparent catchment denudation rates range from 3.8 to 32.9 m/Myr, being significantly higher than those of summit bedrock, which are mostly concentrated between 1 and 5 m/Myr. More resistant lithologies, such as granites and quartzites, sustain summits and inselbergs that denude far more slowly than the adjacent gneiss and mica schist surfaces, indicating the continuous action of differential erosion. The results reveal a denudational contrast between dry (leeward) and humid (windward) slopes (apparent rates of 18.3 ± 1.5 and 13.7 ± 1.2 m/Myr) that becomes sharper and statistically significant after correction for sediment burial, reinforcing mesoclimatic and morphopedological controls. Denudation rates are further modulated by structural lineament density, reflecting inherited basement fabric rather than active tectonics. The denudational contrast between elevated and lowered sectors allows inferring evolutionary timescales on the order of ~25–75 Myr, with the massif-scale differential denudation pointing to an onset by the Late Cretaceous, while more localized compartments record progressively younger individualization through the Eocene–Miocene.