Radiocarbon reservoir ages and water effect in the north-eastern coastal waters of Argentina

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

RADIOCARBON

UNIV ARIZONA DEPT GEOSCIENCES

Año: 2008 vol. 50 p. 119 - 129

0033-8222

AMS 14C dates were obtained 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 tree-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 input of varying content of dissolved, carbonate by rivers and groundwater (hard-water effect) and indicates a serious limitation for shell-based 14C chronologies. Within the interior of Bahía Blanca estuary, ∆R values ranged from -40 to 50 ± 46 as a consequence of the local geological particularities of the environment. This suggests that with some restrictions, the marine calibration curve with standard parameters (∆R = 0) could be used at this location.