A Multi-Proxy Soil–Sediment Framework to Track Paleoenvironmental Changes and Human Occupation in Serra da Capivara, Northeast Brazil

This study investigates how Quaternary colluvial deposits preserved within rock shelters record palaeoenvironmental changes and potential evidence of human occupation in Serra da Capivara, Northeast Brazil (NEB). It integrates morphostratigraphic and granulometric analyses, optically stimulated luminescence (OSL) chronology, phytolith assemblages and indices, and geochemical and mineralogical characterisation (EDXRF, XRD, FTIR, and UV–Vis spectrophotometry) across four sites. Morphostratigraphic and chronological evidence provided the strongest constraints on depositional architecture, sediment accumulation dynamics, and stratigraphic discontinuities, whereas geochemical and phytolith proxies offered complementary insights into environmental conditions and site-use patterns, while remaining more strongly influenced by lithology, taphonomy, and post-depositional processes. Results spanning approximately 37.5–6.0 ka, from the Late Pleistocene to the Middle Holocene, demonstrate that stratigraphic discontinuities and buried palaeosurfaces are associated with both coherent and contrasting responses among proxies, reflecting their differential sensitivity to environmental change, depositional stability, and post-depositional transformation throughout this interval. Phosphorus enrichment was observed in Quaternary deposits relative to the weathered bedrock, indicating allochthonous inputs and providing a useful chemical marker when assessed alongside stratigraphic and archaeological contexts. These findings suggest that the integration of morphostratigraphic, chronological, phytolith, and geochemical approaches strengthens the interpretation of sedimentary archives in rock shelters and provides an integrated basis for evaluating relationships between environmental dynamics and potential pulses of human activity.