26 Reconstructing Environmental Change from Marine, Lacustrine, and Terrestrial Sedimentary Records (Posters)

Saturday, 29 March 2025
8:30 AM - 5:30 PM
North Great Hall

17,000 YEARS OF LEAF WAX N-ALKANOIC ACID DISTRIBUTIONS AND STABLE HYDROGEN ISOTOPES AT LAKE EMANDA (EASTERN SIBERIAN HIGHLANDS)

Paper number: 26-12
Program: Theme Sessions
Time: 8:30 AM – 5:30 PM

Authors

Abstract

Accelerating rates of Arctic warming warrant investigation into past responses to similar rapid warming events in high latitude regions as partial analogs to current change. Evaluation of past climate mechanisms in the Arctic region is limited spatially by the inaccessibility of study sites. By examining an existing lake sediment core from eastern Siberia, we generate a paleoclimate record to assess local responses to targeted warming periods well described in the North Atlantic region. We measure abundance and hydrogen isotope ratios of n-alkanoic acids derived from sediment-extracted fossil leaf waxes spanning 17 ka. We infer this proxy to reflect changes in paleoclimatological and ecological systems in the catchment. A high preference for even n-alkanoic acid carbon chain lengths (Carbon Preference Index > 4) suggests minimal n-alkanoic acid degradation. Dominance of C26 and C28 n-alkanoic acid chain lengths suggests largely terrestrial input of leaf waxes into the lakebed. Changes in relative abundances may align with trends in the catchment’s plant communities, as observed in a published pollen record. Periods of 2H-enrichment and 2H-depletion of n-alkanoic acids in the record tend to align with known periods of global warming and cooling, respectively. Correction for fractionation of leaf wax hydrogen isotopes relative to precipitation will allow assessment of moisture source and seasonality, which may cause trends in the record. Finally, changes in the correlation between the isotope ratios of given chain lengths and the oxygen isotope ratio of a published diatom record may suggest turning points in our record where the behavior of the catchment system is altered by climate effects. Ultimately, the n-alkanoic acid distributions and hydrogen isotopes provide another tool to help fill out a more comprehensive understanding of wider Arctic climate responses to rapid warming events, but may also pose further questions about the behavior of this specific system.

Geological Society of America Abstracts with Programs. Vol. 57, No. 3

doi: 10.1130/abs/2025NE-408474

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