Palynology and sediment slumping in a high arctic Greenland lake

• Published in: Boreas
• Main Author: FREDSKILD, BENT
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1995
• Subjects: Arctic; Greenland; Arctic Lake; Amdrup Land
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.1995.tb00784.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.1995.tb00784.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.1995.tb00784.x

A 103‐cm core from a high arctic lake (80°49′N, 15°00′W) on Amdrup Land, NE Greenland has been analysed for pollen and other microfossils, as well as bulk samples from 10 cores for macrofossils. AMS 14 C‐dating of aquatic mosses ( Drepanocladus exannulatus and Scorpidiurn scorpioides ) revealed that the lowermost 90 cm of the core was deposited during a 1.5‐2 ka interval in the early Holocene, before the appearance of Salix arctica which immigrated to N Greenland c . 7 ka BP. Armeria scabra , now extinct in the area, larval cases and apotomes of Apatcmiu zonella , today not known north of c. 77°N, and other indices point to a climate warmer than that of today. A thin, sandy layer 13 cm below the lake bottom, accompanied by marked changes in the content of pollen and macrofossils, such as the sudden occurrence of large amounts of Salix pollen and leaves, indicates a large hiatus. This is confirmed by the dating to c . 7 ka BP of mosses just below the sand, and of Salix leaves just above it to c . 1 ka BP. The hiatus must be caused by sediment slumping which transported all the sediment from the intervening period to the deeper part of the lake. A similar, sandy layer in the uppermost 2–6 cm may be caused by younger, (sub‐)recent slumping, or both may be the result of the same disturbance. The possibility of a reservoir effect causing too old 14 C‐ages for the moss is discussed.