Palynological implications for Late Glacial to middle Holocene vegetation and environmental history of the Lop Nur Xinjiang Uygur Autonomous Region, northwestern China Hongjuan Jia a, ** , Jingzhong Wang a , Xiaoguang Qin b , Sangheon Yi c, d, * a Experiment and Practice Teaching Center, HeBei GEO University, Shijiazhuang, 05003, China b Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China c Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, 34132, South Korea d Department of Petroleum Resource Technology, Korea University of Science and Technology (UST), Daejeon, 34113, South Korea article info Article history: Received 15 July 2016 Received in revised form 10 November 2016 Accepted 14 November 2016 Available online 1 March 2017 Keywords: Arid China Environmental change Holocene Late Glacial Lop Nur Pollen abstract Lop Nur is located in the northeastern area of the Tarim Basin, in the Xinjiang Uygur Autonomous Region, northwestern China. A 210-cm-deep trench section was collected from the center of the lake. Five accelerator mass spectrometry (AMS) 14 C dating results indicate that the studied section encompasses the Late Glacial to middle Holocene periods (12.8e5.5 cal ka BP). Vegetation and environmental changes in the Lop Nur region can be divided into three stages and six sub-stages, based on significant changes in the pollen assemblages. Dry conditions and desert steppe or steppe vegetation dominated this region from 12.8 to 11.4 cal ka BP. The climate became warmer and wetter at the beginning of the Holocene, and steppe vegetation replaced the previous flora. Steppe vegetation continued to dominate until the middle Holocene (8.7e6.7 cal ka BP), which had the wettest moisture conditions. Increased winter temperatures from 6.7 to 5.5 cal ka BP triggered more evaporation, causing shrinkage of the lowland wetlands. Climate events such as the Allerød oscillation, the Younger Dryas,and events at 9.4 cal ka BP, 8.4cal ka BP, 7.5 cal ka BP, and 7.0 cal ka BP, were recognized in the Lop Nur section. The evidence indicates that climate oscillations in the Lop Nur area were influenced and controlled by changes in global climate. © 2016 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction The formulation of hypotheses about the causes of climatic change requires the synthesis of global and regional climate in- formation from all available sources. Studies performed in north- western China have aided our understanding of changes in vegetation and climate during the late Pleistocene and Holocene (Mischke and Wünnermann, 2006; Huang et al., 2009; Zhao et al., 2009; Wang N. et al., 2013; Wang W. et al., 2013; Lyu et al., 2015; Ran et al., 2015). However, some issues remain unresolved, including a) whether different stages of the Holocene were wet or dry and b) the nature of prevailing hydrothermal regimes and climate change patterns in the Xinjiang Uygur Autonomous Region during the late Pleistocene and Holocene. Previous studies have yielded conflicting humidity results from the same core sampled from Wulungu Lake. Some authors have divided the climate into four stages (Xiao et al., 2006), whereas others have divided it into three (Jiang et al., 2006, 2007; Liu et al., 2008). Xiao et al. (2006), Jiang et al. (2006), and Liu et al. (2008) reported evidence for a dry early Holocene and a moderately dry or wet middle Holocene. Using the same core, Jiang et al. (2007) determined that 9985e5250 cal BP was the wettest phase and 5250e1255 cal BP was the driest phase. Studies of Aibi Lake have also produced contradictory results; the temperature was higher from 11.5 to 10.6 cal ka BP, accompanied byincreased precipitation (Jiang and Wu, 2003). The climate was cool and dry prior to 8 ka BP, 8.0e3.5 ka BP was a warmer moist climate stage, and 3.5 ka BPepresent has been warm and dry (Jiang and Wu, 2003; Wu et al., 1996). In contrast, Wang N. et al. (2013); Wang W. et al. (2013) determined that the Aibi Lake area was subject to increased basinwide moisture conditions between 13,870 and 7430 cal BP. The water level of Aibi Lake increased from approximately * Corresponding author. Geologic Environment Division, Korea Institute of Geo- science and Mineral Resources, Daejeon, 34132, South Korea. ** Corresponding author. Experiment and Practice Teaching Center, HeBei Geo University, Shijiazhuang, 05003, China. E-mail addresses: jhjzjw@sina.com (H. Jia), shyi@kigam.re.kr (S. Yi). Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint http://dx.doi.org/10.1016/j.quaint.2016.11.024 1040-6182/© 2016 Elsevier Ltd and INQUA. All rights reserved. Quaternary International 436 (2017) 162e169