Abstract Luminescence sensitivity is increasingly being used as a fingerprinting tool in sediment provenance and transport studies owing to its dependence on a variety of factors that operate during sediment transport. This study documented basin‐scale variability in quartz thermoluminescence sensitivity across the semi‐arid Sabarmati River basin, western India, by integrating basin‐scale sampling, laboratory luminescence sensitisation experiments, and single‐grain OSL analyses. Quartz TLS ranged from 1.6 to 6.2 Units in bedrock and 66–325 Units in river sediments. Spatial variability in TLS along the river course was random, and it could only be explained through allochthonous aeolian inputs (55–404 Units) from adjacent dunes rather than progressive in‐channel sensitisation as has been reported in other river basins. Laboratory sensitisation studies on bedrock‐derived quartz TLS show up to a two‐fold increase, with diminishing enhancement over successive cycles. Extrapolation of the initial trend suggests that >500 cycles would be required to match the sediment TLS values, and this implies sub‐million to million‐year timescales of repeated sediment reworking. Further, Sabarmati River sediment TLS suggest low 10 Be‐derived denudation rates (<10 mm kyr −1 ). Single‐grain OSL analyses suggest that fewer than 0.5% of exceptionally bright grains dominate the bedrock TLS signal, while non‐luminescent grains constitute up to 99% in bedrock and 60–80% in river sediments. These results suggest that aeolian contributions influence the distribution of single‐grain OSL and thereby determine the bulk TLS and therefore call for caution in the use of TLS as a sediment provenance proxy in dryland river basins that experience aeolian sediment transport. The results also suggest that the abundance of non‐luminescent grains could serve as a provenance indicator.
Panda et al. (Mon,) studied this question.