Chronology of a lacustrine core from Lake Linggo Co using a combination of OSL, 14C and 210Pb dating: implications for the dating of lacustrine sediments from the Tibetan Plateau. (15th November 2017)

• Record Type: Journal Article
• Authors: Hu, Gang; Yi, Chaolu; Zhang, Jiafu; Cao, Guirong; Pan, Baolin; Liu, Jinhua; Jiang, Tao; Yi, Shuangwen; Li, Dehong; Huang, Jianwei
• Is Part Of: Boreas. Volume 47:Number 2(2018)
• Page Start: 656
• Page End: 670
• Publication Date: 2017-11-15
• Subjects: Geology, Stratigraphic -- Quaternary -- Periodicals; 551.79
• DOI: 10.1111/bor.12291
• Languages: English
• ISSNs: 0300-9483

Abstract

Abstract : Vast palaeolakes once occupied the Qinghai‐Tibetan Plateau (TP). Analyses of the sedimentary records of these lakes could potentially provide an extensive dating archive. Many previously constructed age‐depth models simulating lacustrine cores have been principally based on radiocarbon ( 14 C) dating. However, such dating could have been hampered by the so‐called 'lake reservoir effect' (LRE) and the reworking of lakebed sediments, resulting in inaccurate 14 C age‐depth models and limiting interpretations of existing lacustrine palaeoclimatic records. Lake Linggo Co is located on the central TP, in one of the coldest and most arid regions of Tibet. We dated a 9.87‐m‐long lacustrine core extracted from the lakebed at a water depth of ~60 m using a combination of 210 Pb, 14 C and optically stimulated luminescence (OSL) techniques. Some 14 C ages showed significant age reversals; all the 14 C ages were much older than the 210 Pb and OSL ages for the same depths. This could possibly be attributed to the presence of old, inherited carbon, causing the inherited 14 C age to appear unstable during the deposition period. The 210 Pb and OSL ages were roughly concordant, and were also consistent with the stratigraphical succession. We therefore suggest that 14 C dating may, on its own, be inadequate for accurate dating of lacustrine sediment sites on the TP, and that the OSL method should also be applied in order to evaluate the reliability of any 14 C ages. With this approach, we constructed an age‐depth model, revealing sedimentation rates of 1.7, 0.8, 6.8 and 0.6 mm a −1 between 0–1.9, 1.9–4.2, 4.2–4.4 and 4.4–9.4 ka, respectively.