Deciphering late Quaternary land snail shell δ18 O and δ13 C from Franchthi Cave (Argolid, Greece)

This paper investigates the stable isotopic composition from late Pleistocene-Holocene (similar to 13 to similar to 10.5 cal ka BP) shells of the land snail Helix figulina, from Franchthi Cave (Greece). It explores the palaeoclimatic and palaeoenvironmental implications of the isotope palaeoecology of archaeological shells at the time of human occupation of the cave. Modern shells from around the cave were also analysed and their isotopic signatures compared with those of the archaeological shells. The carbon isotope composition of modern shells depicts the consumption of C-3 vegetation. Shell oxygen isotopic values are consistent with other Mediterranean snail shells from coastal areas. Combining empirical linear regression and an evaporative model, the delta Os-18 suggest that modern snails in the study area are active during periods of higher relative humidity and lower rainfall delta O-18, probably at night. Late glacial and early Holocene delta Os-18 show lower values compared to modem ones. Early Holocene delta Os-18 values likely track enhanced moisture and isotopic changes in the precipitation source. By contrast, lower late glacial delta O-18 could reflect lower temperatures and delta(18)Op, compared to the present day. Shell carbon isotope values indicate the presence of C-3 vegetation as main source of carbon to late glacial and early Holocene snails. (C) 2013 University of Washington. Published by Elsevier Inc. All rights reserved.