Holocene hydroclimate in the source region of the Yellow River: A new sediment record from Lake Gyaring, NE Tibetan Plateau. (January 2021)

• Record Type: Journal Article
• Authors: Zhao, Wenwei; Chen, Chunzhu; Jiang, Qingfeng; Ji, Ming; Zhen, Jianan; Yang, Yufeng; Ning, Dongliang; Li, Xiangzhong; Shen, Ji
• Is Part Of: Journal of Asian earth sciences. Volume 205(2021)
• Publication Date: 2021-01
• Subjects: Alpine lake -- Monsoon -- Lake level -- Yellow River -- Bulk organic matter -- Grain size; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2020.104601
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: The first sediment core covering the past 10 kyr is retrieved from Lake Gyaring. Relative abundance of macrophyte and phytoplankton records lake-level fluctuation. Low lake level suggests moisture deficit in lake basin from early to mid Holocene. Evaporation plays a vital role in the response of NETP lakes to climate variations. Abstract: The environmental history of the source region of the Yellow River (SRYR) is vital for understanding its hydrological response to climate processes in the alpine northeastern Tibetan Plateau (TP). In this study, we present the first sediment core record from Lake Gyaring, one of the largest fresh lakes in SRYR, using proxies of total organic carbon, total nitrogen, C/N ratio, δ 13 Corg, chlorophyll a, and grain size, to discuss the environmental variations over past 10 kyr. The results show that sedimentary organic matter mainly originated from the aquatic macrophytes and phytoplankton, the relative abundance of which can serve as a qualitative indicator of lake level changes of Lake Gyaring. From 10 to 6.2 cal kyr B.P., the notable expansion of macrophytes was favored by the warm conditions and an enlarged littoral zone due to lake-level decline. The abrupt cooling between 8.9 and 8 cal kyr B.P. led to temporal lake-level rises that significantly reduced macrophyte primary production. After 6.2 cal kyr B.P., the lake turned to be phytoplankton-dominated following the cooling trend and stepwise increase in lake level. The inferred climate pattern in the lake catchment with an overall dry early to mid Holocene and moister mid to late Holocene disagrees with the Asian monsoon variations. This phenomenon is well recognized by the lake-level records from most of the northeastern TP lakes, implying that strong evaporation in semi-arid lake catchments could have outweighed the increased regional precipitation during early to mid Holocene and vice versa for mid to late Holocene.