Luminescence dating of the late Quaternary sediments in Hangzhou Bay, China

Coastal plain of Hangzhou Bay, to the south of the present Yangtze Estuary, is closely linked to the evolution of the Yangtze River delta. However, absolute age of Pre-Holocene sediments is limited, which hinders the understanding of this area's environmental evolution. In this study, using optically stimulated luminescence (OSL), single aliquots and single grains of quartz and K-feldspar were used to date the late Quaternary sediments in coastal plain on the southern Hangzhou Bay. The vertical difference in particle size composition render either silt- or sand-sized quartz for dating. Cross-checking of multiple OSL dating methods indicated that the upper similar to 65 m recorded the Holocene part of the succession; sediment from a depth of 136.6 m was dated to similar to 180 ka. It was found that the single-grain method was more reliable in comparison to single-aliquot age, the former minimized the effect of signal components. Single-grain quartz and K-feldspar luminescence yielded consistent ages at sample depth of 136.6 m (similar to 160-180 ka), while the latter gave robust age at depth of 115.5 m (similar to 150 ka). This chronology is in general in accordance with neighbouring cores and can constrain paleomagnetic dating results in those cores. Taking together, the study site has thickest Holocene deposits in comparison to the highland centered around Taihu Lake on the southern Yangtze delta. Moreover, the luminescence characteristics of quartz from different sample depths, behaved differently with respect to luminescence sensitivity, signal components and saturation level, perhaps reflecting varied provenance and weathering characteristics caused by climate change.

Automated summary

In this study, optically stimulated luminescence (OSL) dating was used to determine the age of late Quaternary sediments in the coastal plain of southern Hangzhou Bay. The results showed that the single-grain method was more reliable than the single-aliquot method, and the luminescence characteristics of quartz varied with respect to sensitivity, signal components, and saturation level, possibly due to climate change-induced variations in provenance and weathering characteristics.