Timing of Holocene lake highstands around Dawa Co in inner Tibetan Plateau: Comparison of quartz and feldspar luminescence dating with radiocarbon age |
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| Institution: | 1. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China;2. School of Geography, Nanjing Normal University, Key Laboratory of Virtual Geographic Environment, Ministry of Education, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China;3. University of Chinese Academy of Sciences, Beijing, 100049, China;4. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China;5. Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xi''an, 710061, China;6. Qinghai Province Key Laboratory of Physical Geography and Environmental Process, College of Geographical Science, Qinghai Normal University, Xining, 810008, China;7. Academy of Plateau Science and Sustainability, People''s Government of Qinghai Province and Beijing Normal University, Xining 810016, China |
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| Abstract: | Lakes over the inner Tibetan Plateau (TP) are very sensitive to the regional environmental transformations and climate changes. Well-preserved lake sediments around these lakes provide critical geomorphological and sedimentary evidence that can be used to infer the past hydroclimate changes. In this study, a lacustrine section from a sandy shoreline (～74 m above the modern lake) situated to the northwest of modern Dawa Co in the inner TP was investigated using both luminescence and radiocarbon dating methods. Our results demonstrated: (1) the quartz optically simulated luminescence (OSL) dating yielded much younger ages (～4 ka) than that of the post-infrared IRSL (pIRIR) dating of the K-feldspar fraction; (2) fading test showed g-values ranging between 1.34 and 4.46%/decade for quartz OSL signals, which is considered to be responsible for the underestimation of the corresponding ages; (3) the AMS 14C age of the charcoal sample from the section is in line with the K-feldspar pIRIR225 ages, confirming the reliability of the pIRIR225 dates and the underestimation of the quartz OSL ages. The anomalous fading of quartz OSL signals and the consequent age underestimation have been reported in several other lakes on the TP, we presented here for the first time firm evidence of the phenomenon with the help of a robust independent control of AMS 14C age of the charcoal. Based on the pIRIR225 and AMS 14C ages, we conclude that Dawa Co underwent a prominent highstand during the early Holocene (～9–7 ka), which was probably controlled by the large amounts of glacial meltwater input and the increased monsoonal precipitation. |
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| Keywords: | Luminescence dating Radiocarbon dating Quartz anomalous fading Tibetan Plateau Lake level |
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