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Title: Summer and nonsummer climatic signals in speleothem δ 18 O revealed by loess microcodium δ 18 O in East Asia
Speleothem δ18O records from central southern China have long been regarded as a key benchmark for Asian summer monsoon intensity. However, the similar δ18O minima observed among precession minima and their link to seasonal precipitation mixing remains unclear. Here, we present a 400,000-y record of summer precipitation δ18O from loess microcodium, which captures distinct precession cycles similar to those seen in speleothem δ18O records, particularly during glacial periods. Notably, our microcodium δ18O record reveals very low-δ18O values during precession minima at peak interglacials, a feature absent in speleothem δ18O records from central southern China. This discrepancy suggests that the mixed summer and nonsummer climatic signals substantially influence the speleothem δ18O records from central southern China. Proxy-model comparisons indicate that the lack of very low-δ18O values in speleothem δ18O records is due to an attenuated summer signal contribution, resulting from a lower summer-to-annual precipitation ratio in southern China at strong monsoon intervals. Our findings offer a potential explanation for the long-standing puzzle of the absence of 100- and 41-kyr cycles in speleothem δ18O records and underscore the critical role of seasonality in interpreting paleoclimatic proxies in central southern China. These insights also have broader implications for interpreting speleothem δ18O records globally, advocating for a more multiseason interpretive framework.  more » « less
Award ID(s):
2202913
PAR ID:
10631503
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; « less
Publisher / Repository:
National Academy of Sciences
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
122
Issue:
28
ISSN:
0027-8424
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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