Stable isotope and trace element investigation of two contemporaneous annually-laminated stalagmites from northeastern China surrounding the "8.2 ka event"

• Published in: Climate of the Past
• Main Authors: J. Y. Wu, Y. J. Wang, H. Cheng, X. G. Kong, D. B. Liu
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2012
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Greenland; Indian; Pacific; Greenland ice cores; North Atlantic
• Online Access: https://doi.org/10.5194/cp-8-1497-2012; https://doaj.org/article/a65e0f5efd86445b99919cbcd6d54e73

The prominent "8.2 ka event" was well documented in the Greenland ice cores. It remains unclear, however, about its duration, structure and forcing mechanism at low- to mid-latitude regions. Here we use the physical and geochemical data of stalagmites from the Nuanhe Cave in Liaoning Province, northeastern China, to reconstruct a detailed history of East Asian monsoons covering the entire duration of the event. High-resolution chronologies of two contemporaneous stalagmites, each consisting of at least 770 yr annual growth bands, were established by calibrating and anchoring the floating band-counting ages against five high-precision 230 Th dates. Two oxygen isotope profiles replicate each other on annual-decadal timescales despite their difference in growth rates, indicating that the δ 18 O variability has a climatic origin largely associated with changes in the rainfall δ 18 O from the West Pacific during summer season. A signal from the "8.2ka event" was faint in our δ 18 O records, not as significant as Indian monsoon dominated stalagmite δ 18 O records from Qunf in Oman and Dongge in Southern China. However, our δ 13 C and Ba/Ca profiles, as indicators of local environmental changes, provide strong support for a climate reversal centred at 8.2 ka BP, which is likely controlled by winter monsoon circulations via the westerly winds associated with North Atlantic climate. Therefore, we concluded that the winter- and summer-Asian monsoons responded independently to the high northern latitude climate.