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Luminescence-based tracers for Earth-surface processes

Luminescence signals stored in quartz and feldspar grains contain information that goes beyond the quantification of the accumulated energy dose that is used for luminescence dating. The collectivity of all luminescence-based information stored in a sediment, i.e. its luminescence inventories, can provide proxies for tracing earth surface dynamics, including the generation of sediments by rock erosion, as well as the transport and dispersal of sediments by various earth surface processes. Successful applications of luminescence inventories during the last years include – but are not restricted to – the reconstruction of mountain exhumation rates, mixing and transport of soil particles, rock erosion rates, source area weathering and erosion, fluvial sediment transport and coastal sediment dynamics. This versatility and the potential to complement and substitute conventional process tracers make the exploitation of OSL inventories an important research frontier in Earth sciences. Luminescence inventories help to reconstruct sediment movement over time and space using mainly two approaches, (i) tracing sediment pathways from source to sink or (ii) fingerprinting the geographical or geomorphic provenance of sediments in their depositional sinks. Compared to conventional sediment tracers such as mineralogy, geochemistry, granulometry, or fallout radionuclides such as 137Cs and 7Be, OSL-based proxies are low cost, universally applicable, easy to measure and applicable to natural grains without introducing contaminants or altering the natural system. The key strength that differentiates luminescence-based proxies from other tracer methods and thus determines its potential to improve sediment tracing is, however, its potential to bridge between on-site instrumental observations providing insights into short-term Earth surface processes and large-scale reconstructions of the general Earth surface dynamic by terrestrial cosmogenic nuclides (TCN) or other geochronological techniques.

The CLL is working on developing new luminescence-based tracers for Earth-surface dynamics, but also on improving and applying established OSL-based proxies for sediment mobility. This includes the use of luminescence-based information stored in quartz and feldspar grains to better understand vertical and lateral sediment mobility in soil systems (Project C08 of CRC1211, e.g. Reimann et al. 2017 in Quaternary Geochronology), the quantification of sediment production due to weathering and erosion on hillslopes and its link to sediment transport in fluvial systems (Project Wearing Down, e.g. Guyez et al. 2022 in Earth Surface Processes and Landforms), and the reconstruction of sediment dynamics in coastal systems such as erosion and deposition patterns caused by tropical cyclones (e.g. May et al. 2021 in Journal of Geophysical Research).