Holocene Lake Evolution and Glacial Fluctuations Indicated by Carbonate Minerals and Their Isotopic Compositions in the Sediments of a Glacial Melt Recharge Lake on the Northwestern Tibetan Plateau

Abstract

Lakes and glaciers are widely distributed on the Tibetan Plateau and are linked via hydrological processes. They are experiencing rapid changes due to global warming, but their relationships during the Holocene are less well known due to limited coupled geological records. Here, we analyzed the δ13C-VPDB and δ18O-VPDB values and ion content of calcite and aragonite in a 407-cm-long sediment core from Guozha Co, a closed basin on the northwestern Tibetan Plateau supplied by glacial meltwater, in order to understand how the lake responded to glacier changes during the Holocene. Our results indicate that the glacial meltwater lowered the lake’s temperature and the δ18Olake water and δ18Oendogenic + authigenic carbonate values and diluted the ion concentrations in the lake water. Three stages of evolution, 8.7–4.0, 4.0–1.5, and 1.5 kyr BP to present, are distinguished based on the decrease in glacial meltwater recharge. Guozha Co has been a closed basin since at least 8.7 kyr BP, and it has changed from a fresh water lake during 8.7–1.5 kyr BP to a brackish lake from 1.5 kyr BP to present due to several climate events. The famous 4.2 kyr BP cold event was identified in the core at 4.0 kyr BP, while warm events occurred at 6.2, 3.9, 2.2, 0.9, and 0.4 kyr BP. Both glaciers and lakes in this area are controlled by climate, but they exhibit opposite changes, that is, glaciers retreat and lakes expand, and vice versa. Our results provide an accurate interpretation of the cold events based on carbonate minerals and carbon–oxygen isotopes in glacial meltwater–recharged lake sediments.

Elemental interactions between pore water and lake sediments with their environmental significance: a case as Holocene sediments in Guozha Co, northwestern Tibetan Plateau

“…There only contains sparsely distributed desert vegetation. Previous studies reported that the recharge by glacial meltwater decreased during the Holocene, and the lake evolved from a fresh lake with warm climate during 8.7-4.0 kyr BP, to a fresh lake with cold climate during 4.0-1.5 kyr BP, and to a saline lake with salinity of 3.19-3.32 g/L during 1.5 kyr BP to present (Li et al, 2021a), based on the carbonate minerals,…”

“…Table 1). Among the three stages (8.7-4.0 kyr BP, 4.0-1.5 kyr BP, and 1.5 kyr BP to the present) by Li et al (2021a), the most distinct variation in the elements in the water leachate occurred from 1.5 kyr BP to the present (Fig. 2).…”

“…The climate was extremely cold and dry, and the mean precipitation and mean temperature from 1979 to 2013 were 90 mm and -12.9 °C, respectively (Qiao et al, 2017;Qiao and Zhu, 2019). The observed temperature of the surface water was 4.17-5.03°C in September 2015 (Li et al, 2021a). There only contains sparsely distributed desert vegetation.…”

Controls on the elemental variations of lake sediments ： a case as Guozha Co, Tibetan Plateau

“…Paleo-lake water was captured during the burial process of sediments and became the predominant composition of the porewater. Because of the exceptionally low deposition rate (0.2977-0.9697 mm/yr) in Guozha Co (Li et al, 2021a), it might have taken 15 to 33 years to deposit 1 cm-thick sediment.…”

Spatio-Temporal Distribution Characteristics of Glacial Lakes in the Altai Mountains with Climate Change from 2000 to 2020

“…Rainfall in the study area declined in 2006, while temperature has maintained an increasing trend in the region since 2005. Continued warming has caused a great deal of glacial melting in the north, and the effect of meltwater recharge generated by glacier retreat was larger than the impact of reduced precipitation on the glacial lakes [72]. This accumulation of meltwater may feed the expansion of the glacial lakes for the next couple of years.…”