Quaternary calcretes in the Oued Nja Valley, located in the Sa & iuml;ss Basin, Morocco, provide an exceptional record of North African palaeoenvironmental dynamics. This multidisciplinary study, integrating sedimentological, mineralogical and diagenetic analyses, identifies nine calcrete types: root-related, nodular, laminar, massive, conglomeratic, powdery, encrusted, and fracture-filling. These formations reflect complex pedogenic and hydrochemical processes. Pedogenic calcretes, organized in distinct horizons, exhibit both biogenic (rhizoliths, pisoliths, calcified filaments) and abiotic (laminations, dense microfabrics) structures, indicating soil-atmosphere interactions under semi-arid to sub-humid climatic conditions. In contrast, hydrochemical calcretes, formed in shallow aquifers, are characterized by sparitic cements, floating grains and circumgranular cracks, suggesting rapid cementation under arid conditions. Analyses reveal a dominance of calcite (57.79-84.42 % CaCO3) alongside siliciclastic interbeds, pointing to aeolian inputs during dry periods. The genesis and evolution of these calcretes are modulated by the Liassic carbonate substrate, local hydrology, biological activity and tectonics of the South Rifian Corridor (NE-SW, NS and NW-SE faults), recording environmental oscillations between humid phases with dense vegetation and arid periods dominated by evaporation. Compared to Mediterranean calcretes, they are distinguished by their abundance of biogenic structures and proximity to faulted zones. The findings highlight calcretes as key palaeoclimatic and geological markers, with significant implications for sustainable water resource management: massive facies indicate areas prone to aridification, while root-related facies may signal potential for enhanced groundwater recharge. Future geochemical and microstructural investigations could refine these models, enhancing regional palaeoenvironmental reconstructions.