Stable isotope record of palaeoclimatic change in a British Holocene tufa

Abstract

A 9.5 m long, continuous core through Holocene tufa deposits in Derbyshire, UK, was analysed for oxygen and carbon stable isotope variations with a view to palaeoclimatic and palaeoenvir onmental interpretation. The depositional environment of the tufa is well understood and dated using 14C and biostratigraphy. It is argued that smooth variations of up to 1‰ in δ18O of the tufa calcites are caused by changes in the isotopic composition of regional rainfall, which in turn were caused mainly by changes in air temperature (palaeoclimate). In general, lower δ13C values for calcite correspond with higher δ18O values, suggesting a stronger component of soil-derived carbon during warmer climatic phases. A stable isotope approach to reading terrestrial palaeoclimatic records is of widespread application to Holocene and older tufa deposits which are common in carbonate bedrock regions.