I have conducted a modern precipitation and cave drip water analysis in Northern California and developed precisely dated, high-resolution records of stable oxygen (δ18O) and carbon (δ13C) isotope variability from a Lake Shasta Caverns speleothem (LSC3) from Lakehead, California (40.8043°N, 122.3040°W). Analysis of six years of weekly rainfall isotope data (2010-2016) indicates that temperature and moisture source are significant controls on the δ18O and δ2H signature of precipitation that falls in Northern California. U-Th dating of the LSC3 stalagmite reveals that it precipitated from ~35.9 to ~14.3 ka, spanning Heinrich Stadials 1-3, and the last deglaciation, a period when regional records suggest large hydroclimatic changes in western North America (WNA). Increased δ18O and δ13C in LSC3 during the last glacial period (Marine Isotope Stage 2) including the Last Glacial Maximum suggest an increase in subtropical moisture but overall dry conditions in Northern California. This interpretation is supported by slower stalagmite growth rates during the glacial relative to the deglaciation and Marine Isotope Stage 3. Wetter conditions during the BA are suggested by decreased δ13C values and faster stalagmite growth rates. Comparison of the LSC3 record with coeval paleoclimate records from WNA will assist in refining our understanding of regional hydroclimatic variability and will help to determine the stationarity of spatial patterns of change between the north and south across the western United States. Understanding the driving mechanisms of California precipitation variability is critical in this heavily-populated, water stressed region.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07192017-102611 |
| Date | 20 July 2017 |
| Creators | Weisman, Isabelle Ellis |
| Contributors | Dr. Jessica L. Oster, Dr. Marisa Luisa S. P. Jorge, Dr. John C. Ayers |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07192017-102611/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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