4:00 PM - 4:15 PM
[MIS23-15] Temperature change since the latest Pleistocene deglaciation stage recorded in carbonate clumped isotopes of a stalagmite collected in Hiroshima Prefecture, Japan
Keywords:stalagmite, clumped isotopes, temperature change, last glacial period, Holocene
The generated carbon dioxide was carefully purified in column cooled at -10°C, and measured by MAT 253 with applying the baseline correction of He et al. (2012). Each value was adjusted on the absolute reference frame of Dennis et al. (2011). A typical measuring error was within 0.015 permil (1s) that corresponds to 3°C in the temperature range of Hiro-1. We applied the temperature equation based on our own measurements of synthesized calcites of known temperatures, which is very similar to the theoretical equation of Guo et al. (2009).
After eliminating obvious offsets, the temperatures based on the clumped isotope of Hiro-1 was in 29.7−20.7°C (24.8°C in average) during Holocene (11−4 ka), and in 22.4−14.3°C (18.0°C in average) during the latest Pleistocene (18−12 ka). These temperatures are likely higher than the real, by considering that the modern temperature of this cave is 10.7°C. The temperature offset is common between several speleothem studies reflecting Kinetic Isotopic Effect associated with CO2 degassing (e.g. Affek et al. 2014). Although our evaluation involves some uncertainties, we suggest that the temperature difference between Holocene and latest Pleistocene was 6−7°C. This preliminary estimation is broadly consistent to the 1.5 permil difference in oxygen isotope between Holocene and Pleistocene observed in Hiro-1 (Shen et al. 2010).