Revista Brasileira de Geomorfologia

Geomorphology of Pereiro Massif, Northeast Brazil

Thu, 13 Feb 2025 00:00:00 -0300

The Pereiro Massif (Northeast Brazil) is a granite relief situated between the Jaguaribe and Portalegre shear zones, exhibiting strong structural control over its morphology. This study aims to analyze the morphostructural context of the massif and interpret its evolution based on denudation rates, using in situ cosmogenic isotope (¹⁰Be) production, OSL dating of colluvial deposits, and GIS-based morphometric analyses. The results suggest that the massif represents a relief inherited from a lithostructural framework associated with the Brazilian orogeny, with Cretaceous reactivations and Cenozoic denudational cycles. Its formation is primarily attributed to differential erosion, driven by the greater resistance of granitoids compared to the surrounding metamorphic lithologies. There is no clear evidence of neotectonic activity influencing regional morphogenesis. Denudation rates range from 10.1 to 24.6 m∙My^-1, indicating higher denudation trends influenced by lithostructural and topographic controls. Post-Miocene morphodynamics were shaped by the regional semi-arid climate, punctuated by humid paleoclimatic variations that account for colluviation between the Last Glacial Maximum (LGM) and the Younger Dryas.

Remote sensing applied to the morphodynamics of the meandering Usumacinta River in the period 1986-2019

Wed, 12 Feb 2025 00:00:00 -0300

The Usumacinta River (UR), one of the longest and most voluminous rivers in Central America, is a free-flowing river without significant anthropogenic control. However, its fluvial dynamics and interactions with the environment drive changes that are influenced by the hydraulic, morphological, and sedimentary conditions that evolve. Remote Sensing (RS) and Geographic Information Systems (GIS) are increasingly being utilized for the analysis of historical morphological changes in rivers, offering accelerated and predictive insights. In this study, we employed RS and GIS techniques to examine the morphodynamics of UR from 1986 to 2019, focusing on variables such as channel migration, channel width, sinuosity, and slope. Our analysis revealed that 91% of the 1,458 transects (each 1,400 m) exhibited low migration (<50 m) and only 0.61% experienced high migration (>200 m). The UR is characterized by high sinuosity (S = 2.01) and meandering channels with slopes ranging from 0º to 84º. These findings provide crucial data for policymakers and resource managers, offering a foundation for strategies aimed at protecting, conserving, and sustainably managing water resources in the UR basin.