We studied the impacts of geomorphic and weathering processes and mineralogical dynamics on mechanisms controlling the sequestration and mineralisation of soil organic carbon within falling and climbing sand ramps. Analyses of XRD, XRF, SEM, granulometry, paleoclimate, physiochemical attributes, and weathering indices were done over sand ramps in central Iran. The higher frequency of carbonate minerals, sand sediments, well-sorted clastic aggregates, symmetrical grain distribution, high roundness, and minimal quartz corrosion suggest that falling surfaces remain relatively intact, with limited evidence of weathering processes. Despite the development of carbonate minerals on falling sand ramps, the absence of clay minerals and particles promoted weaker organic matter binding compared to climbing surfaces. The higher frequency of secondary clay minerals, the poor sorting of sediments, high angularity, and the formation of micro-scale landforms on granites suggest long-term exposure of climbing surfaces to chemical weathering. These characteristics explain that multiple processes, including weathering, fluvial activity, and aeolian transport, contributed to the formation of climbing surfaces. The greater presence of illite, kaolinite, montmorillonite, and Fe2O3 and Al2O3 oxides supported pedogenesis processes and promoted microaggregate-associated carbon, making SOC less accessible to microbial mineralisation. These findings suggest localized variations in geomorphic and weathering processes and mineralogical structures could affect bio-geochemistry mechanisms controlling the mineralisation of soil organic carbon across the evolution of sand ramps, offering valuable insights into carbon dynamics in arid and semi-arid regions.

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