Stalactite flow rates in a central Chinese cave over the last 9000 years
Abstract
Chinese stalagmites represent unparalleled archives of past East Asian monsoon dynamics. However, the so-called 'amount effect' which links stalagmite oxygen isotope (δ18O) values to monsoon intensity is increasingly questioned. This study introduces a new method to quantitatively reconstruct stalactite discharge (drip rates) to stalagmites, representing a direct hydrological proxy that measures karst aquifer recharge, and by extension effective rainfall. Heshang Cave stalagmite HS4, from central China, grew under a perennial drip point which fluctuates in direct response to annual effective rainfall. The cave system is among the best studied and monitored in the world, providing a strong foundation for calibrating and testing this new proxy. Our analysis shows that drip discharge is highly correlated with stalagmite δ18O, broadly following insolation throughout the Holocene, with centennial-scale variability mainly in phase with δ18O. Flow rates had peak values between 8000-6000 years BP, subsequently declining to minimum flow around 300 years BP. Drip discharge decoupled from δ18O at important intervals in the early, mid and late Holocene. While fluctuations in monsoon rains are clearly coupled to previously identified forcings, we suggest that paleoclimatic drip rates have the potential to redefine our understanding of 'monsoon failure' and to test the drivers embedded in traditional but ambiguous proxies.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC33E1456H
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSES;
- 3373 Tropical dynamics;
- ATMOSPHERIC PROCESSES;
- 1630 Impacts of global change;
- GLOBAL CHANGE