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 14 C and biostratigraphy. It is argued that smooth variations of up to 1‰ in δ 18 O 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 δ 13 C values for calcite correspond with higher δ 18 O 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.