Ba/Ca in <i>Neogloboquadrina pachyderma</i> as an indicator of deglacial meltwater discharge into the western Arctic Ocean

Abstract

Down‐core samples of the planktonic foraminifer Neogloboquadrina pachyderma sinistral from the Mendeleyev Ridge in the western Arctic Ocean have been analyzed for Ba/Ca and δ 18 O. The apparent distribution coefficient for N. pachyderma sin. is estimated at D Ba = 0.22 ± 0.02. A meltwater event is identified at around 11.8 14 C kyr BP and is coincident with elevated Ba/Ca ratios. The barium enrichment is believed to be the result of enhanced weathering and erosion following glaciation. Additionally, barium may have desorbed from shelf sediments as sea level rose. Changes in Ba/Ca correlate with the retreat of the Laurentide Ice Sheet and the evolution of the Mackenzie River drainage basin. Therefore maximum Ba/Ca in Arctic surface waters at 11.8 ka may be indicative of an increase in the export of freshwater from the Arctic to the North Atlantic, potentially contributing to the onset of the Younger Dryas. This work suggests that Ba/Ca in planktonic foraminifera may be a useful indicator of the timing and processes associated with deglaciation.