The Forming Age and the Evolution Process of the Brine Lithium Deposits in the Qaidam Basin Based on Geochronology and Mineral Composition

Abstract

Lithium ore deposits are divided into pegmatite and brine deposits. The Puna Plateau and the Qinghai–Tibetan Plateau (QTP) are home to the most abundant brine lithium deposits worldwide. Very few studies have investigated the chronology of brine lithium deposits. This paper reports the Optically Stimulated Luminescence (OSL) dating measurements for typical brine lithium deposits at QTP, including East Taijnar Salt Lake, West Taijnar Salt Lake, and Yiliping Salt Lake in the central Qaidam Basin. Combining the results of OSL dating with previous studies and mineral composition obtained by X-ray diffraction analysis (XRD), this study summarizes the age and characteristics of the climatic environment during the formation of brine lithium deposits in the Qaidam Basin. The main results are: 1) Brine lithium deposits in the Qaidam Basin began to form since 40 ka. Brine lithium deposits in South America formed during the middle Pleistocene and late Pleistocene, and are older than the deposits in the Qaidam Basin. The lithium deposits of Tibet formed around 4 ka, are the youngest. 2) The climate in East Taijnar Salt Lake and West Taijnar Salt Lake was extremely cold and dry during 27–4.6 ka, with a relatively humid climatic condition at ∼10 ka. After 4.6 ka, the environment was comparatively more humid around both lakes. Yiliping Salt Lake had a dry climate since 38.09 ka, and the climate in the Three Lakes area is mainly controlled by the westerlies in the Holocene; and 3) East Taijnar Salt Lake, West Taijnar Salt Lake and Yiliping Salt Lake were located in the same secondary basin during the late Pleistocene. However, tectonic activity around 40 ka led to the evolution of Yiliping Salt Lake into an independent basin. East Taijnar Salt Lake and West Taijnar Salt Lake separated around 27 ka, and then deposited the lower salt layers until the Holocene. The substantial amount of detrital minerals that the Nalinggele River brought during the Holocene led to a brief desalination of East Taijnar Salt Lake. The upper salt layer was deposited in East Taijnar Salt Lake and West Taijnar Salt Lake during this period due to the extremely dry climate.

Connections between Evaporite Deposition and Glacial Periods since the Middle Pleistocene in Salt Lakes in the Western Qaidam Basin, China

“…1b) featured salt deposition in the Quaternary, the salt layer having gradually increased and thickened since the early Pleistocene. The main salt deposition periods in the Gas Hure, Mahai, Yiliping and Kunteyi Salt Lakes occurred after the middle Pleistocene (Ma et al, 2011); 2: drill core ZK402 (Huang and Han, 2007); 3: drill core ZK312 (Huang and Han, 2007); 4: drill core ZK336 (Huang and Han, 2007); 5: drill core ZK2605 (Huang and Han, 2007); 6: drill core ZK4613 (Huang and Han, 2007); 7: drill core SG-1 (Han et al, 2014a); 8: drill core ZK3208 (Ma et al, 2020); 9: profile MXK2 (Chen et al, 2020); 10: profile D18 (Chen et al, 2020); 11: profile D12 (Chen et al, 2020); 12: profile D08 (Gu et al, 2022); 13: profile WMX1 and WMX2 (Gu et al, 2022); 14: profile KP4 (Chen et al, 2022); 15: drill core ZK701 (Huang and Han, 2007); 16: drill core ZK801 (Huang and Han, 2007); 17: drill core 15YZK01 (Chen et al, 2017); 18: drill core ZK4012 (Liu and Zhang, 1992). (Shen et al, 1993;Huang and Han, 2007;Chen et al, 2017;Ma et al, 2020).…”

Nature of Volatile Organic Matter in Lake Sediments as a Reflection of Paleoclimate Changes Occurring at 4 ka in the Central Qaidam Basin

“…All selected sediment samples were dated using optically stimulated luminescence in the Luminescence Dating Laboratory of the Qinghai Institute of Salt Lakes, Chinese Academy of Sciences. The dating of all samples have been done in our previous work, and the reliability and accuracy of the dating results have been discussed in the paper (Ma et al, 2021). The effective age of the salt-bearing strata could not be identified because of the low content of quartz and feldspar, although according to the lithology, this layer should be the product of an arid environment in the 4 ka BP period.…”