New marine reservoir age corrections from coastal Greenland waters and the eastern Arctic Ocean

Radiocarbon (¹⁴C) dating is the standard method for obtaining the age of marine sediments of Holocene and late Pleistocene age. For accurate calibrations, however, this tool relies on precise knowledge of the local radiocarbon reservoir age of the surface ocean, i.e. the regional difference (ΔR) from the average global marine calibration dataset. This parameter has become impossible to measure from modern mollusk samples because of ¹⁴C contamination from extensive testing of thermo-nuclear bombs in the second half of the twentieth century. The local reservoir age can thus only be calculated from the radiocarbon age of samples collected before AD 1950 or from sediment records containing absolute age markers, derived from e.g. tephrochronology or paleomagnetism.

Knowledge of the marine reservoir age around Greenland and in the Arctic Ocean is extremely sparse, and relies on work by only a few studies. No information exists for the Kara Sea, East Siberian Sea and the western Chukchi Sea, and the coastal seas around Greenland are represented by very few measurements, clustered in local patches. This study presents results of a series of new radiocarbon measurements on historical mollusk collections from Arctic Expeditions of the late 19^th and early 20^th Century. The new samples are from central east Greenland, the entire western Greenland coastline and the east Siberian Arctic extending into the northern Bering Sea.