24-21 Holocene Climate Variability in Northeast Greenland inferred from Sedimentary Leaf Wax Hydrogen Isotopes

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

Poster Booth No.: 49

Presenting Author:

Abigail Cermak

Authors:

Cermak, Abigail Marie¹, Stein, Redmond², Perren, Bianca³, Bradley, Raymond S⁴, Balascio, Nicholas L.⁵, Bakke, Jostein⁶, D'Andrea, William J⁷

(1) Lamont-Doherty Earth Observatory of Columbia University, Palisades, , (2) Lamont-Doherty Earth Observatory of Columbia University, Palisades, , (3) NERC British Antarctic Survey, Cambridge, , (4) Geosciences, University of Massachusetts Amherst, Amherst, , (5) Bates College, Lewiston, , (6) Department of Earth Science, University of Bergen, Bergen, , (7) Lamont-Doherty Earth Observatory of Columbia University, Palisades, ,

Abstract:

Lacustrine sediments from the Arctic are important archives of past climate variations and ecosystem changes. Here we present a 7.5 kyr record of leaf wax (n-alkane) distributions and their hydrogen isotope (δ²H) values from lake Latesommersø, NE Greenland. Latesommersø (82.23°N, 33.52°W) is located in Wandal Dal, a 50 km-long valley that drains meltwater from the Greenland Ice Sheet and several small ice caps. The δ²H values of long chain n-alkanes (C₂₉ and C₃₁) show little variation over the last 7500 yrs, while δ²H values of mid-chain n-alkanes (C₂₅ and C₂₇) show greater variability. The temporal trends in the δ²H values of the various n-alkanes suggest a mixture of two different hydrogen isotope signals. To disambiguate these isotope signals, we apply an unmixing approach using non-negative matrix factorization (NMF) to evaluate the changing source contributions of individual n-alkanes to Latesommersø sediments through time. We then use the NMF results to develop a model for a purely terrestrial (δ²H_terr) and a purely aquatic (δ²H_aq) n-alkane δ²H record. The δ²H_terr record, interpreted as δ²H of summer-biased precipitation, reveals increasing δ²H values between 7-5 ka, followed by long term cooling with multicentennial-scale minima centered at 3.5 ka, 2.3 ka, and 1.5 ka. This δ²H_terr record shows a striking similarity to marine-based records of Atlantic Water advection (Werner et al., 2013) and sea ice extent (Müller et al., 2012) in eastern Fram Strait, suggesting that isotopes in precipitation in Northeast Greenland have tracked the location and temperature of source-water evaporation. This study provides an important new record of isotopes in High Arctic precipitation and demonstrates the utility of NMF-based isotope unmixing in leaf wax studies. 

 

Müller, J., Werner, K., Stein, R., Fahl, K., Moros, M., & Jansen, E. (2012). Holocene cooling culminates in sea ice oscillations in Fram Strait. Quaternary Science Reviews, 47, 1–14.

Werner, K., R. F. Spielhagen, D. Bauch, H. C. Hass, & E. Kandiano (2013). Atlantic Water advection versus sea-ice advances in the eastern Fram Strait during the last 9 ka: Multiproxy evidence for a two-phase Holocene. Paleoceanography, 28, 283–295.

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