Middle to late Holocene hydroclimate variability revealed by multi-proxy stalagmite records from Jinfo Cave, central-west China

Abstract

The pattern and cause of middle-to late-Holocene hydroclimatic variability in central-west China remain unclear. We present a new pair of stalagmite isotopic (δ18O and δ13C) records and trace element ratio (Mg/Ca, Ba/Ca, and Sr/Ca) records from Jinfo Cave, central-west China. We established a uranium-series chronology that shows that the stalagmite grew between 5.6 and 0.6 kyr BP. The similarities between our δ18O stalagmite record and other published records suggest that δ18O generally reflects overall monsoon intensity or rained-out effect between the cave site and moisture source, but not necessarily regional rainfall amount. Corresponding changes in Mg/Ca, Ba/Ca, Sr/Ca, and δ13C are mostly dependent on local factors, such as the nature of the ecosystem above the cave, water-rock interactions, and the prior calcite precipitation effect. As the δ13C records bear a remarkable resemblance to Mg/Ca, Ba/Ca, and Sr/Ca records, we extracted the first principal component (PC1) of the four records and identified the PC1 as a regional hydroclimate proxy. The bandpass filter and cross wavelet transformation results show that the ∼500 years periodicity of PC1 exhibits in-phase oscillations with solar activity and the El Niño-Southern Oscillation (ENSO) throughout the middle to late Holocene, suggesting that changes in solar activity influence centennial hydroclimate variation and are amplified by ENSO. Another prominent feature seen in PC1 is a progressive positive shift from 3.0 kyr BP, which indicates that central-west China moved toward a drier climate over this period. We attribute this climate transition to a strengthening El Niño event and its impact on oceanic and atmospheric anomalies.