Organic geochemical reconstructions of the late quaternary climate history of the Sierra Nevada
Abstract/Contents
- Abstract
- Organic geochemical proxy measurements in sediments from Swamp Lake, Yosemite NP, in the central Sierra Nevada of California provide evidence of climatic change on millennial and centennial timescales over the last ~20,000 years. Proxy measurements in bulk sediments (TOC, TN, C/N, [delta]13Corg, [delta]15N, biogenic silica, magnetic susceptibility) record the response of the lake environment, in terms of primary productivity, OM sources, microbial OM regeneration and secondary production, and detrital input, to climate-driven changes in temperature, seasonal ice cover, lake mixing regimes, runoff and lake level. Parallel changes in the relative abundances of n-alkane biomarkers provide more specific information about lake level during the Holocene epoch. The inferred environmental changes at Swamp lake correlate with other Sierra Nevada paleo-records, and with reconstructed sea surface temperatures along the California margin. Parallel changes in the Swamp Lake and SST records over the past ~20,000 years provide new evidence that continental climate in the Sierra Nevada and the California Current system have responded, on multiple timescales, to common drivers in North Pacific ocean-atmospheric circulation. Measurements of compound-specific hydrogen isotope ratios in sedimentary leaf wax n-alkanes ([delta]Dwax) provide insight into the nature of the link between North Pacific and Sierra Nevada climate over time. The [delta]Dwax composition of Swamp Lake sediments is primarily controlled by changes in the [delta]D of precipitation, which is in turn influenced by the moisture sources and trajectories of winter storms. The Swamp Lake [delta]Dwax record reveals a long-term change in precipitation seasonality and/or storm trajectory over the Holocene, driven by seasonal insolation, as well as centennial- to millennial-scale fluctuations reflecting changes in the relative importance of northerly and southerly storm types. These apparent "regime shifts" in North Pacific atmospheric circulation resemble modern, short timescale responses to ENSO and the PDO, but their underlying causes remain unknown.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Street, Joseph Horace |
|---|---|
| Associated with | Stanford University, Department of Geological and Environmental Sciences. |
| Primary advisor | Chamberlain, C. Page |
| Primary advisor | Paytan, Adina, 1961- |
| Thesis advisor | Chamberlain, C. Page |
| Thesis advisor | Paytan, Adina, 1961- |
| Thesis advisor | Diffenbaugh, Noah S |
| Thesis advisor | Maher, Katharine |
| Thesis advisor | Ravelo, Ana Christina |
| Advisor | Diffenbaugh, Noah S |
| Advisor | Maher, Katharine |
| Advisor | Ravelo, Ana Christina |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Joseph Horace Street. |
|---|---|
| Note | Submitted to the Department of Geological and Environmental Sciences. |
| Thesis | Ph.D. Stanford University 2012 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Joseph Horace Street
- License
- This work is licensed under a Creative Commons Attribution Non Commercial Share Alike 3.0 Unported license (CC BY-NC-SA).
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