Research Paper OSL chronology for lacustrine sediments recording high stands of Gahai Lake in Qaidam Basin, northeastern Qinghai–Tibetan Plateau QiShun Fan a, b , ZhongPing Lai a, * , Hao Long a, b , YongJuan Sun a , XiangJun Liu a, b a Luminescence Dating Group, Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, 18 XinNing Road, Xining 810008, PR China b Graduate School of Chinese Academy of Sciences, Beijing 100049, PR China article info Article history: Received 18 October 2008 Received in revised form 8 February 2009 Accepted 10 February 2009 Available online 21 February 2009 Keywords: Luminescence dating High lake levels Palaeoenvironmental change Qaidam Basin Qinghai–Tibetan Plateau abstract The Qaidam Basin in the northeastern Qinghai–Tibetan Plateau (QTP) is one of the largest hyper-arid intermontane basins in the northern hemisphere, and has abundant records for the study on palaeo-lake level fluctuations and palaeoclimatic changes. Significant efforts have been invested to define the timing of shoreline deposits using radiocarbon dating. However, due to the dating limit, the absence of organic materials and carbon reservoir effects for radiocarbon dating in arid areas, it is difficult to establish a reliable chronology for shoreline deposits. Therefore, controversy exists regarding the chronology for the high lake level in the Qaidam Basin, as well in the QTP. Some proposed that high lake levels occurred during late Marine Isotope Stage (MIS) 3, while others recently argued that the highest lake level in the QTP and adjacent regions existed in MIS 5. In Gahai Lake (now a salt lake), we investigated a section comprising lacustrine and shoreline deposits, which was about 25 m above the present lake level. Seven samples were collected for quartz optically stimulated luminescence (OSL) dating. A sample collected from a fine sand layer (the bottom of the section, and 12 m above the present lake level), which was assumed to have been deposited underwater, gave an OSL age of 82  8 ka. It suggested that the lake level was at least 12 m higher than present in late MIS 5. The high lake level could maintain till about 73  6 ka, and then decreased. This lake level decrease resulted in a gravel layer deposit between 73  6 and 63  6 ka (roughly during MIS 4). The lake level rose again (about 24 m above the present lake level) between 63  6 and 55  5 ka (roughly in early MIS 3). No lacustrine or shoreline deposits higher than the top of the current section were found around Gahai Lake. Thus, higher than present lake levels in Gahai Lake occurred in both late MIS 5 and early MIS 3. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction The northeastern Qinghai–Tibetan Plateau (QTP) is located at a triple junction of influences from the Southeast Asian monsoon, the westerlies, and the Southwest Indian monsoon (Bryson, 1986) and this makes it sensitive to past climatic variability. The Qaidam Basin is a hyper-arid intermontane basin on the northeast of the QTP (Fig. 1), which records a history of lake level fluctuations and climatic changes. Chen and Bowler (1986) investigated the geomorphic evidence for high lake levels and suggested that two large shorelines were preserved along the margins and pediments of the basin which represented mega-lakes. Significant efforts have been invested to define the timing of shoreline deposits using radiocarbon dating on the QTP (Chen and Bowler,1985; Zheng et al., 1990; Li, 2000), and ‘the great lake period’ (Zheng et al., 1996; Li, 2000) or ‘rather warm and humid period’ (Shi et al., 1999, 2001) has been proposed for the period of 40–25 ka (corresponding to late MIS 3). Also using 14 C, similar observations were reported from adjacent regions such as the Tengger Desert, the Badain Jaran Desert and the Taklamakan Desert in western China (Pachur et al., 1995; Wu ¨ nnemann et al., 1998; Zhang et al., 2002, 2004; Yang et al., 2006, 2008). However, due to the dating limit of radiocarbon (<40 ka), the absence of organic materials and radiocarbon reservoir effects in arid areas, it is quite difficult to establish reliable chronologies for shoreline or lacustrine sediments (Zhang et al., 2006). In recent years, luminescence dating has been successfully applied to dating shoreline deposits from around the world (see a review by Jacobs (2008), and references therein), as well as in western China such as in the QTP (Madsen et al., 2008; Li et al., 2008; Liu et al., 2010), the Lop Nur (Wang et al., 2008) and Jilantai–Hetao regions * Corresponding author. E-mail addresses: zplai@isl.ac.cn, zplai@yahoo.com.cn (ZhongPing Lai). Contents lists available at ScienceDirect Quaternary Geochronology journal homepage: www.elsevier.com/locate/quageo 1871-1014/$ – see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.quageo.2009.02.012 Quaternary Geochronology 5 (2010) 223–227