Reconstruction of Climate Changes Based δ18Ocarb on the Northeastern Tibetan Plateau: A 16.1-cal kyr BP Record From Hurleg Lake

Abstract

Hydroclimate evolution history and changes in the Tibetan Plateau play significant roles in depicting paleoclimate and evaluating climatic conditions in the coming future. However, the interaction of the westerlies and the Asian monsoon complicates our understanding of the mechanism of climate variation over the Tibetan Plateau. In this study, we assessed the paleoclimate of Hurleg Lake, which was previously located in the convergence area of the East Asian monsoon and westerly wind. We first reconstructed the climatic conditions based on fined-grained authigenic carbonate δ18O (δ18Ocarb), plant-derived proxies of C/N, and n-alkane-derived δ13C31. In the Hurleg Lake, δ18Ocarb was controlled by δ18O changes of the lake water and evaporation. The climate evolution since ∼16.1 cal kyr BP can be classified into three stages. The Lateglacial (16.1–11.0 cal kyr BP) was characterized by a warm-wet climate in the beginning, followed by a cold-dry climate since 12.0 cal kyr BP. Typical warm and cold phases occurred during 14.8–12.0 cal kyr BP and 12.0–11.1 cal kyr BP, which may correspond to the Bølling/Allerød (B/A) and Younger Dryas periods, respectively. The early to mid-Holocene was generally characterized by a warm-wet climate; however, notable cold-dry intervals occurred at ∼8.3 cal kyr BP. The Late Holocene (after 4.8 cal kyr BP) displayed a significantly cold-wet climate. Finally, we examined the possible mechanisms responsible for the climate variability in the study area. The results showed that the long-term warm trend in the Lateglacial and colder trend after early Holocene was controlled by insolation. The Asian summer monsoon and the westerlies played a significant role in determining moisture sources during the Lateglacial. The East Asian monsoon contributed greatly to the moisture variation from the early to mid-Holocene, whereas the westerly winds dominated during the late Holocene. Combined, our findings highlight the complex changes in hydroclimate conditions since the last glacial in the Tibetan Plateau and provide crucial implications for comprehending the hydroclimate pattern in the transition zone of westerlies and Asian monsoon.

Temperature and Climatic Seasonality Affecting C3 Versus C4 Plants Since the Last Deglacial on the Northeastern Tibetan Plateau

“…During 11.1 ∼ 9.0 cal kyr BP timescale, the paleoenvironmental characteristics recorded by different lakes on the northeastern Tibetan Plateau were relatively consistent. The increased CIA values together with negative δ 13 C carb values in the Hurleg Lake indicate a warm/wet climate (Ma, Wei, et al., 2021, 2023) (Figures 7b and 7c). Besides, on the northeastern Tibetan Plateau, the increased pollen‐based MAT and MAP of Ximencuo Lake (Figures 7d and 7e) (Herzschuh et al., 2014), high temperature of Qinghai Lake (Figure 7f) (Hou et al., 2016), and dramatic depleted 18 O carb of Genggahai (Figure 7g) (Qiang et al., 2017) all suggestive a warmer and wetter climate in the early Holocene phrase of 11.1 ∼ 9.0 cal kyr BP.…”

“…In the timing of 7.2 ∼ 4.8 cal kyr BP, the C 4 plants rose again and peaked at ∼5.7 cal kyr BP (Figure 4b). In the meantime, the C/N ratio increased significantly, indicative of more terrestrial plants input to lake sediments (Figure 4c) (Ma, Wei, et al., 2021). In this phase, the pollen concentration and the Chenopodiaceae content in the Hurleg Lake displayed an obvious increase‐decrease pattern, corresponding to the C 4 plants variation (Figures 4d and 4e) (Zhao et al., 2007).…”

“…In the past few decades, C 4 plants on the Chinese Loess Plateau have been widely studied, and insights into the driving mechanism of C 4 plants have been connected to the EASM and temperature (Liu et al., 2005; Vidic & Montañez, 2004; Yang et al., 2015; Zhang et al., 2003). In the Hurleg Lake, northeastern Tibetan Plateau, the hydroclimate was dominated by Westerly in the late Holocene, whereas the Eastern Asian Monsoon controlled the climate variation before that (Ma, Wei, et al., 2021). From the Last Deglacial to the mid‐Holocene, it could be observed that there were three typical monsoon enhancements in 15.7 ∼ 13.5 cal kyr BP, 11.0 ∼ 9.0 cal kyr BP, and 6.0 ∼ 5.0 cal kyr BP, respectively (Figure 8e) (Dykoski et al., 2005).…”

“…(b) CIA values of the Hurleg Lake HL18‐3 core (Ma et al., 2023). (c) δ 13 C carb of the Hurleg Lake HL18‐3 core (Ma, Wei, et al., 2021). (d) mean annual precipitation of the Ximencuo Lake on the northeastern Tibetan Plateau (Herzschuh et al., 2014).…”

Late glacial and Holocene climate in the Kunlun Pass region (northern Tibetan Plateau) inferred from a multi-proxy lake record

“…10.4 cal ka BP and highest precipitation during the first half of the Holocene (10.4-5.0 cal ka BP) were reconstructed for Lake Ximencuo at the eastern margin of the Tibetan Plateau based on pollen data (Herzschuh et al, 2014). Warmer conditions during the first half of the Holocene were also recorded at lakes Qinghai, Hurleg, Hala and Donggi Cona (with the periods of 10.8-4.5 cal ka BP, 11.1-4.8 cal ka BP, 11.5-7.5 cal ka BP and 11.9-6.8 cal ka BP, respectively; Shen et al, 2005;Mischke et al, 2010b;Yan and Wünnemann, 2014;Ma et al, 2021;Fig. 9).…”