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

YURENA YANES; IZETA , ANDRES; CATTÁNEO G. ROXANA; COSTA, T.; GORDILLO, SANDRA

HOLOCENE (SEVENOAKS)

SAGE PUBLICATIONS LTD

Lugar: London; Año: 2014 vol. 24 p. 1193 - 1205

0959-6836

The isotopic fingerprint of terrestrial gastropods is progressively used as a credible natural paleoenvironmental archive. Most published work has used this proxy at tropical and temperate latitudes of the Northern Hemisphere, and has concentrated on entire-shell analysis. The present study provides entire-shell and intra-shell isotopic profiles to infer both average and seasonal late Holocene environmental conditions in central Argentina (30°S). Shells of Plagiodontes daedaleus (Gastropoda: Odontostomidae) were collected from the Alero Deodoro Roca-Sector B site, one of the few archeological sites in central Argentina rich in shells collected by pre-Hispanic hunter-gatherer groups. Ancient entire shells exhibited values that were ~2.5? higher in δ13C and ~1.8? higher in δ18O than modern individuals, pointing to higher abundance of C4 plants and overall drier conditions (lower relative humidity and/or higher rain δ18O) during 4.5-1.7 cal. kyr BP than today, in agreement with published regional proxies. Intra-shell isotopic profiles suggest that modern and fossil specimens deposited their shells throughout two-to-three summer/winter cycles. Intra-shell δ18O values varied ~5?, matching with the seasonal variation of rain δ18O values. The extent of seasonality was similar during 4.5-1.7 cal. kyr BP and today. Intra-shell δ13C values varied ~2-3? and did not portray distinct seasonal cycles, depicting minimal seasonal variations in the snail diet. This work illustrates that South American terrestrial gastropods have great potential for paleoenvironmental studies.