RADIOCARBON RESERVOIR AGES AND HARD-WATER EFFECT FOR THE NORTHEASTERN COASTAL WATERS OF ARGENTINA.

GÓMEZ, E.A., BOREL, C.M., AGUIRRE, M.L., MARTÍNEZ, D.E.

RADIOCARBON

Univ. of Arizona, Dept. of Geosciences

Lugar: Arizona; Año: 2008 vol. 50 p. 119 - 129

0033-8222

AMS 14C dates were measured for 18 mollusk shells collected alive along the Buenos Aires province coast, Argentina, over the period AD 1914-1935. Reservoir ages were estimated for all samples on the basis of the three-ring calibration curve for the Southern Hemisphere (SHCal04) and the marine ¦¤R values as the difference between the conventional 14C age and the age deduced from the marine, mixed-layer model calculation (Marine04) . For most coastal locations a great ¦¤R scatter was observed, ranging from 191 to 2482 yr, which is explained by the income of varying content of dissolved, old soil carbonate by rivers and groundwater (hard-water effect) and indicates a serious limitation for shell-based 14C chronologies. For the internal area of Bah¨ªa Blanca estuary the ¦¤R ranged from -40 to 50 ¡À 46 as consequence of the local geological features of the environment, suggesting that they could be justified by some restrictions on the use of the marine calibration curve with standard parameters (¦¤R = 0) at this location.