Abstract

This study examines surface coverings in the sub-middle sector of the S & atilde;o Francisco River, situated in the semi-arid core of northeastern Brazil, to reconstruct environmental changes from the Last Glacial Maximum through the Holocene. A morphostratigraphic approach integrated sedimentological, geochemical, and Optically Stimulated Luminescence (OSL) analyses of colluvial, fluvial, fluvio-aeolian, and aeolian deposits. Geochemical results indicate predominantly felsic sediment sources and high degrees of chemical weathering, reflecting palaeoclimatic conditions wetter than at present, punctuated by periods of renewed severe semi-aridity. OSL ages spanning similar to 20 ka to the Late Holocene reveal sedimentation pulses synchronous with major global climate events-including Heinrich stadials, the B & oslash;lling-Aller & oslash;d, the Younger Dryas, and the Holocene Climatic Optimum-followed by progressive drying from the onset of the Late Holocene, with a return to aeolian deposition. Alternation between erosional and aggradational phases suggests strong regulation of the S & atilde;o Francisco's hydro-sedimentary regime by large-scale climatic teleconnections, with implications for understanding the resilience and vulnerability of semi-arid environments under future climate-change scenarios. The findings underscore the importance of Quaternary deposits as palaeoenvironmental archives and contribute to addressing key knowledge gaps on the geomorphological and palaeoclimatic dynamics of northeastern Brazil.