Tree-ring analyses have contributed significantly to investigations of climate change and climate cycles, including the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO) and El Niño/Southern Oscillation (ENSO). Stable isotope climate proxies (?18O, ?D, and ?13C) have enhanced traditional ring-width data, although poor preservation of ancient wood has generally constrained reconstruction of stable isotope proxy records to the Holocene and Late Pleistocene. An opportunity to apply these stable isotope methods to older wood has been presented by recovery of remains of Mixed-Coniferous Boreal Vegetation, in Early Pliocene (4-5 Ma) deposits at Strathcona Fiord, Ellesmere Island, Canada (~79°N). An exceptionally well-preserved tree trunk, identified as Larix (larch) through wood anatomical characteristics, from this high Arctic site provided a 203-year tree-ring record, from which we present the first high-resolution, secular isotope record of Pliocene climate. ?18O, ?D, and ?13C isotope values indicate a variable climate with alternating intervals of cool/wet to warm/dry weather. These fluctuations in climate may be attributable to phase changes in climate cycles observed in the record. A growing season mean temperature of 14.4 °C was calculated from isotopic analysis of gastropod shells. Palaeoclimatic modeling of tree isotope values has revealed growing season temperatures of 11-15 °C, and estimated isotope values of precipitation of 18.3 (?18O) and 228 (?D). Both palaeotemperature estimates and source water calculations are comparable to those found in a modern Boreal Forest. Time-series wavelet analysis was applied to these data revealing prominent short (<10 years), intermediate (16-35 years) and long-term (~45-50 years) cyclicity. These are the highest resolution climate cycles recovered from the pre-Holocene terrestrial record, providing evidence for decadal scale cyclicity similar to the NAO and/or PDO 4-5 million years ago.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-06262006-162818 |
| Date | 03 July 2006 |
| Creators | Csank, Adam Zoltan |
| Contributors | Renaut, Robin W., Patterson, William P., Holmden, Chris, Cota-Sánchez, J. Hugo, Basinger, James F., Ansdell, Kevin M. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-06262006-162818/ |
| Rights | unrestricted, 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 University of Saskatchewan 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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