Holocene Climate Evolution of Continental Western Eurasia Constrained By Stable-Isotope and Cation Geochemistry of U-Th-Dated Speleothems and Meteogenic Travertine
Reliable reconstructions of global and regional climate during the Holocene (11,700 years ago to present) are vital to constraining the natural range of climate variability and testing state-of-the-art models, which seek to forecast the near- and long-term impact of anthropogenic greenhouse forcing....
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| Format: | Text |
| Language: | English |
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Digital Scholarship@UNLV
2018
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| Online Access: | https://digitalscholarship.unlv.edu/thesesdissertations/3212 https://digitalscholarship.unlv.edu/cgi/viewcontent.cgi?article=4215&context=thesesdissertations |
| Summary: | Reliable reconstructions of global and regional climate during the Holocene (11,700 years ago to present) are vital to constraining the natural range of climate variability and testing state-of-the-art models, which seek to forecast the near- and long-term impact of anthropogenic greenhouse forcing. Much of continental Eurasia is still underrepresented, however, in geological proxy reconstructions of Holocene climate variability, and the vast majority of paleoclimate data only reflect conditions during peak summer months (JJA) or the growing season. The paucity of winter proxy data has therefore been cited as a possible explanation for the current mismatch between geological proxy-based and climate-model reconstructions of Holocene temperature, but testing the hypothesis first requires additional datasets. In this series of studies, I seek to strengthen our knowledge of Holocene climate evolution in continental western Eurasia and mitigate the seasonal bias in paleoclimate proxy datasets by investigating two sites of freshwater carbonate deposition in western Russia: 1) Kinderlinskaya Cave, located in the southern Ural Mountains, and 2) the Izhora Plateau, south of the Gulf of Finland. Two speleothems collected from Kinderlinskaya Cave, which grew over the entire Holocene epoch, were analyzed for stable isotopes of oxygen and carbon. Carbon-isotope data constrain the timing of permafrost degradation and afforestation for the southern Ural Mountains, and the stable-isotope composition of oxygen in speleothem calcite is shown to reflect Holocene temperature evolution during the winter season. Centennial-scale trends in oxygen-isotope data are further utilized to establish a climate dynamic relationship between winter air temperature over western Russia and perturbations to the North Atlantic Current system over the last 11,700 years, providing a foundation from which to evaluate the regional climate response to feedbacks associated with anthropogenic warming. Early–Middle Holocene deposits of meteogenic ... |
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