Variation of summer precipitation δ<sup>18</sup>O on the Chinese Loess Plateau since the last interglacial
Zeke Zhang, Gaojun Li, Yanjun Cai, Zhengyu Liu, Zhisheng An
Abstract
ABSTRACT Orbital‐scale East Asian Summer Monsoon (EASM) variations inferred from loess deposits in northern China and speleothems from southern China display different dominant periods, complicating our understanding of monsoon response to insolation and ice‐volume forcings. Here we integrate a new microcodium δ 18 O record from a high‐resolution last interglacial loess profile with previously published data and provide a composite microcodium δ 18 O record on the Chinese Loess Plateau (CLP) since the last interglacial. The composite microcodium δ 18 O record displays distinct precessional cycles, consistent with speleothem δ 18 O records, but with different amplitude contrast (particularly during the peak interglacials). We propose that both loess and speleothem δ 18 O records exhibit covariations at precessional timescale oscillations. The discrepancy between loess and speleothem from southern China can be attributed to the influences of other processes besides summer precipitation on the proxies. A slight difference in amplitude between microcodium and speleothem δ 18 O records implies that the EASM is also influenced by inland surface boundary conditions, which has important impacts on the occurrence of EASM precipitation. Therefore, microcodium δ 18 O from the Chinese loess–paleosol sequences can be regarded as a representative proxy of EASM precipitation in northern China and then a reliable proxy reflecting the variation of EASM intensity.