Holocene paleoenvironmental (~4.5-1.7 cal. kyr BP) conditions in central Argentina inferred from entire-shell and intra-shell stable isotope composition of land snails.

YURENA YANES; IZETA , ANDRES; CATTANEO, GABRIELA; COSTA, T.; GORDILLO, SANDRA

San Rafael, Mendoza

Congreso; XII International Conference of Archaeozoology; 2014

International Council for archaeozoology

The isotopic composition of terrestrial gastropods is increasingly used as a paleoenvironmental proxy. The majority of published studies, however, has used this approach in mid-to-low latitude localities of the Northern Hemisphere, and mainly provides data derived from entire-shell analyses. This study presents entire-shell and intra-shell isotopic data to deduce average and seasonal late Holocene environmental conditions in central Argentina (30°S). The species Plagiodontes daedaleus (Odontostomidae) was recovered from the Alero Deodoro Roca-Sector B site, one of the rare archeological sites in central Argentina that contains shelly accumulations associated with pre-Hispanic hunter-gatherer societies. Fossil entire shells showed values that were, on average, ~2.5? higher in δ13C and ~1.8? higher in δ18O than modern specimens. This suggests that during 4.5-1.7 cal. kyr BP conditions were drier (lower relative humidity and/or higher rain δ18O) and C4 plants were more abundant than at present. These findings agree with other published independent proxy data from the region. Intra- shell isotopic profiles suggest that modern and fossil individuals grew their shells throughout two-to-three summer/winter cycles. Intra-shell δ18O values varied ~5?, which matched with the range of rain δ18O values between seasons. The magnitude of seasonality was comparable during4.5-1.7 cal. kyr BP and the present. The intra-shell δ13C values varied ~2-3? and did not show distinctive seasonal cycles, pointing to reduced seasonal variations in snail dietary habits. This study shows that snailshells from South America have great potential for paleoenvironmental inferences