Holocene glacimarine sedimentary environments in fiords of Disko Bugt, West Greenland

Abstract

Acoustic and sedimentary properties of three fiord systems were examined in the region of Disko Bugt, West Greenland to understand variability in the processes, rates and sources of sediment delivery during the late glacial and Holocene. Kangerluk and Kangersooq of western Disko are dominated by meltwater inputs of sediment from local ice fields of the island interior. Modern sediments are delivered primarily via overflow currents (rainout), occasional bottom currents and small amounts of iceberg rafting where exposure to Baffin Bay allows penetration of the West Greenland Current. 14C and acoustic-derived accumulation rates for the last 1–2 ka vary from about 1 mm a −1 in distal fiord settings to more than 5 mm a −1 in proximal sites adjacent to actively building deltas. These rates are generally larger than has been observed in other Greenland and Baffin Bay fiords. The tidewater terminus of Inland Ice at Ikerasak is also meltwater dominated but produces lower than expected sediment accumulation due to low gradients of the outlet ice and resistant substrates. These high latitude West Greenland fiords are subarctic in character and contrast significantly with colder polar-type fiords at similar latitudes in East Greenland. Sediment deposition which was focused in the outer Disko fiords during the late-glacial and early Holocene, is due to one of two possible mechanisms: standstill of local ice or enhanced rafting of sediment from Disko Bugt icebergs. This study contributes to the debate on the extent of glaciation and Holocene spatial variability in fiord processes of West Greenland.