Cave atmosphere controls on stalagmite growth rate and palaeoclimate records

Abstract

AbstractCave atmosphere PCO2 partially controls calcite deposition on stalagmites by changing the thermodynamic drive of drip water to deposit calcite. The dissolved carbon dioxide contained in karstic percolation water is generally controlled by the soil PCO2, and this CO2 will degas in any void spaces with a lower PCO2, including caves. If void space PCO2 is higher than the PCO2 of the water, dissolution may occur. Measured cave air PCO2 ranges of several caves in different climate regimes suggest that soil temperature is a major control on cave air PCO2, but that the observed trend deviates from the modelled trend when soil carbon dioxide production is moisture-limited. Calcite deposition models illustrate how soil and cave air PCO2 can influence stalagmite growth rates, and demonstrate how gradual temperature changes can skew the geochemical proxy signal in stalagmites in favour of certain seasons and eventually can result in total cessation of growth.