Marine Reservoir Corrections: St. Helena, South Atlantic Ocean

Abstract

We present the first marine reservoir age and δR determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and δR determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14 C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman's button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815-1835.