Downstream dilution of quartz luminescence sensitivity due to rapid erosion in the tectonically active Peloritani Range, NE Sicily

Abstract Low optically stimulated luminescence (OSL) sensitivity is commonly observed in quartz from tectonically active catchments, suggesting limited or short-lived conditions favorable for sensitization. We characterize the OSL sensitivity of quartz sand within a small, tectonically active catchment in Sicily using modern fluvial samples and a hillslope soil sample. We investigate how OSL sensitivity varies with bedrock lithology, weathering proxies, and topographic metrics. OSL sensitivity spans three orders of magnitude (60–2800 counts/Gy/mm 3 ) with no clear linkage to bedrock source. The soil sample exhibits the highest OSL sensitivity, and positive relationships between OSL sensitivity, magnetic susceptibility, and weathering intensity suggest that pedogenic hillslope processes enhance quartz OSL sensitivity. In contrast, fluvial sediments show low OSL sensitivity and a modest inverse relationship to channel steepness and hypsometry. OSL sensitivity decreases downstream, suggesting that highly sensitized grains from hillslope soils are progressively diluted by low OSL sensitivity sediment likely generated by rapid bedrock erosion in the catchment. These results highlight a hierarchy of controls: bedrock lithology sets the initial OSL sensitivity, hillslope processes enhance it, rapid erosion dilutes it, and fluvial transport modulates it through mixing, explaining why tectonically active catchments rarely preserve quartz with high OSL sensitivity.