LUMINESCENCE DATING OF LACUSTRINE SEDIMENTS FROM CUOE LAKE ON THE CENTRAL TIBETAN PLATEAU

Luminescence dating technology has been used for chronological constraints on lacustrine sediments due to the ubiquitous materials (e.g., quartz and feldspar) as dosimeters, and a relatively long dating range, compared with the commonly used radiocarbon dating method. However, quartz dating on the Tibetan Plateau may suffer from dim and unstable luminescence signals. In the current study, we investigate a lake-related outcrop from the shore of Cuoe Lake on the central Tibetan Plateau. Both coarse-grained quartz and K-feldspar fractions were extracted, and OSL and post-IR IRSL signals were measured from these fractions, respectively. Combining the stratigraphy analysis and dating results, this study shows that: (1) quartz appears to be unsuitable for dating because of very dim natural signals and even anomalous fading (average g-value: 4.30 +/- 2.51 %/decade). The suitability of the applied pIRIR protocol measured at 150 degrees C (pIRIR(150)) for K-feldspar samples was confirmed by a set of luminescence tests; (2) compared with the luminescence-based chronology, the C-14 age of shells from the same sediment layer yielded older age by similar to 7 ka, which is likely attributed to hard water reservoir effect in Cuoe Lake; (3) the lake level reached its peak and maintained high-stand during the early Holocene (similar to 9.4-7.1 ka). This study highlights the applicability of K-feldspar luminescence dating when the counterpart quartz OSL is insensitive and encounters anomalous fading.

Automated summary

This study investigates luminescence dating technology on lacustrine sediments in the Tibetan Plateau, specifically focusing on the issues with quartz dating and the more reliable results from K-feldspar. The study also highlights the presence of a hard water reservoir effect in Cuoe Lake and the variation of lake levels during the early Holocene period.