ARCUS | Arctic Research Consortium of the United States

6th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Karl Ljung
Authors   Karl Ljung
Category   Physical Science
Title   A paleoecological study of the Pleistocene-Holocene transition in the Kap Farvel area, South Greenland
Affiliation   Quaternary Geology, Lund University, Lund, Sweden

Abstract

A sedimentary sequence from a small lake situated on Taterakasik peninsula in the Kap Farvel area, South Greenland, was investigated with respect to pollen and other microfossil content, as well as loss-on-ignition and magnetic susceptibility values. The 14C dates suggest that sedimentation started shortly before 12 300 cal yrs BP. and thus covers the transition from the supposedly cold Younger Dryas into the warmer Preboreal. The primary aim of the analysis was to interpret the climatic and vegetational shifts during this period.
The results show that Younger Dryas was cold and dry (continental climate). Immigration and establishment of terrestrial plants was very limited, due to the cold and dry environment. However, the production of the green algae Pediastrum was high, suggesting that the summers were fairly mild and ice free.
After the end of the Younger Dryas cooling the terrestrial vegetation expanded rapidly. The climate became warmer and more humid. The productivity in the lake increased due to warmer climate and higher influx of nutrients by increased run-off caused by higher precipitation and snowmelt.
The absence of marine dwelling dinoflagellates (Hystrix) during the Younger Dryas cooling indicates that the ocean was ice covered throughout the year. After the transition into the Preboreal, occurrence of marine organisms - most likely brought to the lake by sea-spray indicate that the ocean was open for at least parts of the year. The ice-covered ocean during the Younger Dryas made the climate more continental and after the transition into the Preboreal the open waters made the climate milder and more humid.