Early‐middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy)

Abstract

This paper compares stable isotope (δ 18 O and δ 13 C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ 18 O (δ 18 Os) of modern specimens ( Pomatias elegans , Cornu aspersum , Eobania vermiculata , Helix ligata and Marmorana fuscolabiata ). In contrast, interspecific shell δ 13 C (δ 13 Cs) variability was significant, probably due to different feeding behaviour among species. The δ 18 Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of 18 O‐depleted winter rainfall in their δ 18 Os is lost. This suggests that δ 18 Os and δ 13 Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ 18 Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ 13 Cs trend suggests a transition from a slightly 13 C‐enriched to a 13 C‐depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ 13 Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO 2 concentration. Copyright © 2010 John Wiley & Sons, Ltd.

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