The timing and duration of the Holocene East Asian summer monsoon (EASM) maximum and the interpretation of Chinese stalagmite δ18O records have long been disputed. Notably, interpretations of Holocene EASM variations are frequently based on a single record or study area and are often contradictory. In this study, we conducted stable isotope analyses of four Holocene stalagmites from Chongqing, southwest China. The results reveal differences in the timing of the Holocene EASM maximum and to try to resolve the inconsistency we analyzed and statistically integrated a total of 16 Holocene stalagmite records from 14 caves in the EASM region. The resulting synthesized Holocene stalagmite δ18O (δ18Osyn) record is in agreement with other EASM records and confirms that stalagmite δ18O records are a valid indicator of EASM intensity, rather of local precipitation amount. The δ18Osyn record shows that the EASM intensified rapidly from the onset of the early Holocene; notably, however, there were distinct EASM oscillations in the early Holocene, consisting of three abrupt millennial-scale events. This indicates that, contrary to several previous interpretations, the early Holocene EASM was unstable. Subsequently, during 8–6 kyr BP, the EASM was relatively stable and strong, with the strongest monsoon occurring during 8–7 kyr BP. This evidence of a stable and strong mid-Holocene EASM in eastern China is in accord with the classical view of a mid-Holocene Optimum in China.
Bibliographical noteFunding Information:
This work was supported by National Key R&D Program of China (2016YFC0502301), grants from the National Natural Science Foundation of China (41572158, 41272192, 41072141, and 41888101), and the Fundamental Research Funds for the Central Universities grants, Southwest University (XDJK2012A003). This study was also partially supported by the Science Vanguard Research Program of the Ministry of Science and Technology (MOST) (106-2628-M-002-013 to C-CS), the National Taiwan University (105R7625 to C-CS), and the Higher Education Sprout Project of the Ministry of Education, Taiwan ROC (107L901001 to C-CS).
- East Asia
- Stalagmite δO
- climatic optimum
- early Holocene
- millennial-scale events
- summer monsoon