Millennial-scale Asian monsoon variability during the late Marine Isotope Stage 6 from Hulu Cave, China

Abstract

A precisely 230Th-dated stalagmite δ13C profile from Hulu Cave, China, is presented to characterize the frequency and pattern of millennial-scale Asian monsoon (AM) variability from 160.6 to 132.5 ka. Evidence for an antiphased relationship of the δ13C and δ18O on the millennial scale suggests that the δ13C is indicative of the local hydrological cycle associated with changes in AM strength. Owing to the δ13C responding to AM changes more sensitively than the δ18O, we could identify 15 strong AM events that correlate to cold intervals recorded in Antarctic ice cores within 230Th dating uncertainty. This result supports a dynamic link of AM strength and southern hemispheric climates via the cross-equatorial airflows. Power spectrum analysis shows a predominant periodicity of 1.5–2.5 ka for the δ13C profile, similar to the Dansgaard-Oeschger frequency during the last glacial period. Moreover, the AM events are characterized by rapid transitions at the onset, suggesting that the observed millennial-scale AM variability is likely forced by northern high-latitude climates via north–south shifts of the Intertropical Convergence Zone associated with the bipolar seesaw mechanism. As evidence for a common mechanism for ice age terminations, a strong AM event (~134 ka) surrounding Termination II is analogous to the Bølling-Allerød warming interval.

The Asian Summer Monsoon: Teleconnections and Forcing Mechanisms—A Review from Chinese Speleothem δ18O Records

“…A large number of Chinese speleothem δ 18 O records can be utilized to characterize millennial-scale climate variability corresponding to Dansgaard-Oeschger events [214] and Heinrich stadials/interstadials [215] in the Northern Hemisphere. This list include records from the Hulu [5,9,71], Sanbao [9], Dongge [12], Dragon [52], Songjia [139], Suozi [216], Xinya [163], Xinglong [161], Kulishu [77,161], Wulu [43,146], Kesang [21], Xiaobailong [13,160], Dashibao [43], Yangkou [167][168][169], Sanxing [119], Yongxing [173], Qingtian [69], Xianyun [158,159] caves, etc. Among the above records, the Hulu [5,9,71], Sanbao [9], Kesang [21], Dongge [12], Xinya [163], Yangkou [167][168][169], Kulishu [77], Xinglong [161], Xiaobailong [160] and Suozi [216] records are incorporated in the SISAL_v1 database.…”

East Asian summer monsoon climates and cave hydrological cycles over Dansgaard-Oeschger events 14 to 11 revealed by a new stalagmite record from Hulu Cave

“…The inverse process operates under drier and colder climatic conditions. Notably, the similarity of speleothem δ 13 C and δ 18 O records is also demonstrated during the penultimate glacial period (Wang et al, 2018).

Figure 5.(A and B) Results of a replication test of δ 13 C records from Hulu Cave.

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“…Under isotopic equilibrium conditions, the δ 18 O records of the stalagmites of Hulu Cave reliably reflect the δ 18 O signal of meteoric precipitation. Modern observations of dripwater and rainwater at the cave site support this interpretation (Wang et al, 2018). Following the reasoning of previous studies (Wang et al, 2001, 2008; Liu et al, 2014; Duan et al, 2015; Cheng et al, 2016; Wang et al, 2018), we conclude that the stalagmite δ 18 O record is a proxy of the East Asian summer monsoon (EASM), with intervals of δ 18 O depletion representing stronger monsoon.…”

“…Modern observations of dripwater and rainwater at the cave site support this interpretation (Wang et al, 2018). Following the reasoning of previous studies (Wang et al, 2001, 2008; Liu et al, 2014; Duan et al, 2015; Cheng et al, 2016; Wang et al, 2018), we conclude that the stalagmite δ 18 O record is a proxy of the East Asian summer monsoon (EASM), with intervals of δ 18 O depletion representing stronger monsoon. However, stalagmite δ 18 O records are likely to integrate the effects of complex hydroclimatic processes, including moisture sources, degree of Rayleigh fractionation, and seasonal duration and intensity of monsoon rainfall.…”

“…However, compared to δ 18 O records, they have been underutilized in paleoenvironmental studies of speleothems in China. Nevertheless, in a specific cave environment, δ 13 C and trace elements can be applied as hydrological tracers at a local scale (Genty et al, 2003; Sinclair et al, 2012; Huang et al, 2016; Zhao et al, 2016; Wang et al, 2018). Moreover, a relationship between δ 13 C and trace element ratios in speleothems has been observed; for example, owing to the impact of prior calcite precipitation (PCP) and CO 2 degassing under low-flow conditions, metal/Ca ratios and δ 13 C are elevated in dripwater and hence in stalagmites (Treble et al, 2003; Johnson et al, 2006; Fairchild and Treble, 2009; Stoll et al, 2012; Chen and Li, 2018).…”