22-EPN3-027: Dust-Carbon-Climate Feedbacks Tested Through Detailed Independent Dating of Arctic Wind-Blown Dust Sequences on Greenland (Part 2 – Laboratory Analyses)
Visit by Thomas Stevens of Uppsala University (Sweden) to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 04 – 13 March 2023.
Report Summary: Over a 10 day visit to the TA facility a total of 67 (45 macrofossils and 22 bulk sediment samples) radiocarbon ages were obtained from loess samples taken around Kangerlussuaq in western Greenland. This represents the largest dataset on such sediments in Greenland, and complements our existing luminescence and radiocarbon analyses on similar or duplicate samples. The aim of the work is to develop reliable independent age models for loess accumulation in Greenland, and thereby allow analysis of past climate, permafrost and dust over the last c. 6-7 thousand years. In particular, our aim was to test the cause of the offsets between luminescence and radiocarbon dating uncovered in our previous work, which represents a significant obstacle to developing age models for Greenlandic loess.
The new data represent a significant step towards resolving this. A first outcome is that macrofossil dating in these sediments seems extremely problematic, with most yielding post bomb ages indicating significant modern carbon contamination. A second outcome is that the high and low temperature bulk carbon dating shows more promise, and reveals extremely young ages (last 150 yrs to post bomb) for the upper c. 15-20 cm of sediment in the profiles. This is reinforced by the luminescence data, and suggest extremely rapid recent accumulation and high dust storm activity in the region. Finally, we will use the new ages to derive robust age models for past climate reconstructions in west Greenland, an area currently undergoing rapid climate change.
