A 280,000-Year Temperature and Productivity Reconstruction From the Great Salt Lake in the Western US Using Long-Chain Alkenones
Abstract
Long-chain alkenones form a key class of biomarkers that allows for paleoclimate reconstruction in most global ocean regions. Recent studies have revealed that many continental lakes also contain alkenones. Futhermore, the distribution of lacustrine alkenones changes linearly with temperature, just as in marine settings, making them a powerful quantitative paleotemperature proxy for continental regions. We have recently found abundant alkenones in the Great Salt Lake (GSL) basin, located in Utah in the western US. The lake sediment contains the well-studied C37:4, C37:3, and C37:2 long-chain alkenones, as well as significant amounts of C38:4, C38:3, C38:2 and C39:3, C39:2. A temperature calibration for C37 alkenones was recently carried out at Brown University for Lake George in New York, further confirming the linear relationship between temperature and alkenone unsaturation index. We have obtained samples of GSL from a sediment core (~2000-yr resolution) that dates back ~280ka BP. We determined long-chain alkenone distribution and abundances to infer temperature conditions and lake productivity changes across multiple glacial/interglacial cycles. Previous research on the GSL basin is primarily qualitative, providing estimates of lake levels and salinity conditions using sedimentological and paleobiological proxies. We provide for the first time a quantitative temperature reconstruction for the GSL region. Furthermore, recent publications have suggested a link between salinity and the percentage abundance of C37:4 alkenones in lakes. By measuring alkenone distribution in hypersaline GSL, we assess the extent to which this link exists in such an arid region. Our study provides insight into the degree to which the western US has been affected by large-scale climate oscillations in the past. In addition, it provides a temperature reconstruction that has the potential to illuminate timing and periodicity of temperature oscillations throughout the GSL region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP11D..04L
- Keywords:
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- 3344 Paleoclimatology (0473;
- 4900)