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: Wu, J. Y., Wang, Y. J., Cheng, H., Kong, X. G., Liu, D. B.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Greenland; Indian; Pacific; Greenland ice cores; North Atlantic
• Online Access: https://doi.org/10.5194/cp-8-1497-2012; https://cp.copernicus.org/articles/8/1497/2012/

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.