Paper No. 5
Presentation Time: 8:00 AM-12:00 PM
HOLOCENE AND LAST INTERGLACIAL CONTINENTAL CLIMATE INFERRED FROM INSECTS AND N-ALKANES IN LAKE SEDIMENTS FROM NORTHWEST GREENLAND
Continental records of climate in the Arctic from past warm periods may yield crucial insights into the impacts of future warming. Sediments from warm periods that predate the Last Glacial Maximum (LGM), however, are rare in glaciated regions due to widespread erosion. Here we present preliminary temperature reconstructions and n-alkane abundances from Holocene and pre-LGM lake sediments preserved within a relict landscape in northwest Greenland. Sediment cores were collected from Wax Lips Lake (informal name) <2 km from the modern Greenland Ice Sheet margin in Nunatarssuaq, Greenland in the summers of 2012 and 2014. Chronostratigraphy was determined using radiocarbon dating of aquatic moss from intact sediment laminae in five parallel cores and indicates that the record spans from beyond the range of 14C dating (>48000 cal yr BP) to the Late Holocene. Radiocarbon-dead material is interpreted as dating to the Last Interglacial Period (LIG) ~130ka with a stratigraphic hiatus through the Last Glacial Period. Temperatures were inferred using chironomid species assemblages compared with a training set from northeastern North America, and indicate early Holocene and LIG temperatures considerably warmer than the Late Holocene. The distributions of n-alkanes downcore were compared with modern soil, plants, and bulk surface sediment samples and used to interpret relative contributions from aquatic and terrestrial plants. Temperature changes are considered against relative changes in the source of n-alkanes to infer climate and environmental conditions through the Holocene and likely the LIG in northwest Greenland.