An absolute paleotemperature record from 10 to 6Ka inferred from fluid inclusion D/H ratios of a stalagmite from Vancouver Island, British Columbia, Canada

By using continuous helium flow during the crushing of calcite speleothem samples, we are able to recover liberated inclusion waters without isotopic fractionation. A paleotemperature record for the Jacklah Jill Cave locality, Vancouver Island, BC, was obtained from a 30-cm tall stalagmite that grew 10.3–6.3Ka ago, using δ18O values of the crushed calcite and of the inclusion water as inferred from its δD. It is found that the locality experienced mean annual temperature variations up to 11°C over a 4-Ka period in the early Holocene. At the beginning of the period, local temperature quickly increased from a minimum of ∼1°C to around 10°C, but this early climate optimum, about 3°C warmer than today, only lasted for ∼1200years. About 8.6Ka ago, temperature had declined to ∼7°C, approximately the same as the modern cave temperature. Since then, the study area has experienced only minor temperature fluctuations, but there was a brief fall to ∼4°C at around 7Ka ago, which might be caused by a short lived expansion of local alpine glaciers. The long-term T-dependence of δD was 1.47‰/°C, identical to the value in modern precipitation.