Asian Hydroclimate Changes and Mechanisms in the Preboreal from an Annually‐laminated Stalagmite,Daoguan Cave,Southern China |
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| Authors: | LIU Shushuang LIU Dianbing WANG Yongjin and ZHAO Kan |
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| Institution: | College of Geography Science, Nanjing Normal University, Nanjing 210023, China,College of Geography Science, Nanjing Normal University, Nanjing 210023, China,College of Geography Science, Nanjing Normal University, Nanjing 210023, China and College of Geography Science, Nanjing Normal University, Nanjing 210023, China |
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| Abstract: | One‐year‐resolved and annually‐counted stalagmite multi‐proxies (δ18O, δ13C, and layer width) from Daoguan Cave, Guizhou Province revealed detailed variability regarding the Asian Summer Monsoon (ASM) and local humidity across Bond events (BE) in the Preboreal. During BEs 8 and 7, 1.5± enrichments in δ18O values were generally consistent with high‐ to low‐latitude climate changes. In detail, the decadal‐scale minor δ18O oscillations in BE8 were broadly less than the mean value, in contrast to the significant changes in local soil moisture derived from the δ13C values and layer records. In the mid‐BE7, δ18O variability was generally above the average level, and higher‐ amplitude variations were observed in the three proxy indicators. Wavelet analysis on the total δ18O time series and across the specific time windows of BEs 8 and 7 identified periodicities of about 130, 60, and 20‐a, respectively. Exceptionally strong in BE7, the 60‐a cycle, pervasively observed in instrumental studies, became prominent starting at 11.4 kaBP. Thus, glacial background conditions are important for suppressing the ASM intensity in BE8, while during BE7, tropical hydrological circulations were potentially actively involved. Consequently, climate internal oscillations, analogous to modern conditions, might have occurred in the distant past once the link between the tropical ocean and atmosphere was established as occurs today. |
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| Keywords: | Daoguan Cave the Preboreal Bond Event ASM global changes |
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