Changes in Driftwood Delivery to the Canadian Arctic Archipelago: The Hypothesis of Postglacial Oscillations of the Transpolar Drift

Аннотация

Driftwood appears to be absent in the Beaufort Gyre but abundant in parts of the Transpolar Drift (TPD), which crosses the Arctic Ocean from the Chukchi Sea to the vicinity of northeastern Greenland. Nearly 300 radiocarbon dates on Holocene driftwood from the Canadian Arctic Archipelago reveal two regions with contrasting histories of driftwood incursion: the region accessible to wood brought into Baffin Bay by the West Greenland Current and the rest of the archipelago, which receives wood from the Arctic Ocean. We hypothesize that when the TPD was deflected westward along northern Greenland, wood was delivered widely to the Canadian Arctic Archipelago; when the TPD exited entirely through Fram Strait via the East Greenland Current, little or no wood was delivered to most of the archipelago, but some continued into Baffin Bay via the West Greenland Current. A split TPD delivered wood to both regions. The regional driftwood incursion histories exhibit multiple maxima and minima that can be explained through this hypothesis. The Larix to Picea ratio of wood arriving in the Canadian Arctic Archipelago has also changed through time. This may indicate varying contributions from Russian versus North American sources, which in turn may indicate variable mixing of wood en route. The inferred discharge paths of the TPD were apparently stable for intervals ranging from several millennia to centuries or perhaps only decades. The last major switch broadly correlates with the onset of Neoglaciation. Variations in the path and strength of the TPD may have important oceanographic and climatic consequences downstream in the North Atlantic Ocean.