부산대학교 도서관

The stable oxygen (δ¹⁸O) and carbon (δ¹³C) isotope ratios of small mammal dental carbonate are potentially valuable proxies for past environmental conditions. However, the application of these proxies to reconstructing Quaternary climate variability has hitherto been limited, due to 1) uncertainties in the relationship between the d18O values of rodent teeth and meteoric water, and 2) a poor understanding regarding the influences of ecological and environmental factors on tooth isotopic compositions. A modern study was therefore undertaken to investigate how the δ¹⁸O and δ¹³C compositions of rodent dental carbonate reflect environmental conditions in Britain. The results demonstrate that a robust relationship exists between the δ¹⁸O values of rodent teeth and meteoric water in mid-latitude regions. Since the δ¹⁸O of meteoric water correlates with temperature, the δ¹⁸O values of rodent teeth reflect climate. The modern relationship was applied to three British Quaternary sites (West Runton, Cudmore Grove, and Marsworth) to reconstruct the δ¹⁸O of past meteoric water. Reconstructed δ¹⁸O values were coupled with the δ¹⁸O compositions of fossil shells to quantify mean summer palaeotemperatures. These palaeotemperatures are comparable with existing palaeoclimate evidence from the three sites. Rodent remains from British cave deposits (Westbury Cave and Gully Cave) were also investigated to reconstruct millennial-scale palaeoclimatic fluctuations. Stratigraphic changes in average tooth δ¹⁸O values are consistent with expected palaeoclimate changes at the sites. These results demonstrate that the δ¹⁸O values of rodent teeth can generate reliable records of Quaternary climate variability. The modern study also showed that the δ¹³C values of rodent teeth from Britain record the δ¹³C of C3 vegetation. However, the δ¹³C compositions of modern teeth are significantly depleted relative to pre-modern teeth. Isotopic analyses of recent rodent teeth indicate that this d13C change must have occurred within the past 2000 years, due to anthropogenic impacts on atmospheric CO2 and vegetation.