Variable influx of West Greenland Current water into the Labrador Current through the last 7200 years: a multiproxy record from Trinity Bay (NE Newfoundland)

Abstract

A multiproxy study of marine sediment gravity core AI07-06G from Trinity Bay, Newfoundland, recorded changes in the strength of the Labrador Current (LC) during the Holocene. From ca. 7.2–5.7 cal kyr BP, Trinity Bay’s seafloor was influenced by cooled Atlantic water derived from the West Greenland Current (WGC) Davis Strait branch, merging into the relatively cold LC. This Atlantic water influence gradually decreased after ca. 5.7 cal kyr BP, reaching a minimum at ca. 4.9 cal kyr BP. In contrast, surface temperatures were relatively low due to cold surface water dominated by sea ice and meltwater carried south by the LC. Icebergs from outlet glaciers around Baffin Bay were abundant in the LC prior to ca. 5.5 cal kyr BP. From ca. 4.9–2.9 cal kyr BP, bottom waters became slightly colder and salinity decreased, as increased mixing of the water column brought less saline surface waters towards the seafloor. This may be explained by a weaker North Atlantic subpolar gyre, transporting less Atlantic water from the WGC to the (outer) LC. Arctic meltwater transport was reduced as glacial melting decreased at the end of the Holocene Thermal Optimum. At ca. 2.9 cal kyr BP, bottom waters returned to colder, more stable conditions, indicating a slight decrease in bottom-water ventilation. After ca. 2.1 cal kyr BP, surface water temperatures dropped and sea ice flux increased. The seafloor of Trinity Bay saw warmer conditions, consistent with a stronger subpolar gyre and increased influx of Atlantic-sourced water.