Luminescence characteristics of quartz from Holocene delta deposits of the Yangtze River and their provenance implications

Abstract

Abstract The optically stimulated luminescence (OSL) sensitivity and OSL signal components of quartz grains were used to investigate provenance changes of Holocene sediments from the Yangtze River delta. The variation of luminescence sensitivity was observed in multiple grain aliquots and single grains of quartz from different sedimentary units of the Yangtze River delta. Laboratory experiments suggest that repeated dosing/bleaching cycles increase the luminescence sensitivity of quartz from the studied sediments. High variable thermal activation curves were observed even for samples from the same sedimentary unit, implying highly diverse sources for the delta deposits of the Yangtze River. Different sedimentary units show quartz with similar OSL component contributions, and repeated dosing/bleaching cycles and heating treatment are unable to affect the relative contributions of the fast and medium components to the bulk OSL signal. The samples from unit 1 (U1, tidal river, 15–11 ka), unit 2 (U2, estuary, 11–9 ka) and unit 6 (U6, delta plain, ca. 1 ka to the present) show relatively higher luminescence sensitivity in comparison to unit 3 (U3, tidal sand ridge, 9–4 ka), unit 4 (U4, prodelta, 4–2.5 ka) and unit 5 (U5, delta front, 2.5–1 ka), implying changing sediment sources over time. Such a temporal variation of sediment source can be explained by the transgressive/regressive history of the Yangtze River delta as well as by Asian monsoon variability since the last deglaciation. It demonstrates that luminescence sensitivity of quartz has great potential for tracing sediment sources in the Yangtze River delta, but more work is needed to characterize specific sources to establish a source-to-sink linkage.