DOI: 10.1016/j.palaeo.2014.10.024
论文题名: Eocene-Oligocene latitudinal climate gradients in North America inferred from stable isotope ratios in perissodactyl tooth enamel
作者: Zanazzi A. ; Judd E. ; Fletcher A. ; Bryant H. ; Kohn M.J.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 417 起始页码: 561
结束页码: 568
语种: 英语
英文关键词: Climate
; Eocene-Oligocene
; Perissodactyl
; Stable isotope
; Tooth enamel
英文摘要: The Eocene-Oligocene transition (~. 34. Ma) was one of the most pronounced episodes of climate change of the Cenozoic. In order to investigate this episode of global climate cooling in North America, we analyzed the carbon and oxygen stable isotope composition of the carbonate component of 19 perissodactyl (horse and rhino) tooth enamel samples from the Eocene-Oligocene rocks of the Cypress Hills Formation (southwestern Saskatchewan, Canada); we then compared the results with previously published data from the US Great Plains (Nebraska, South Dakota, and Wyoming).Average (±1σ) perissodactyl enamel δ13C values (vs. V-PDB) in the Eocene (-8.8±0.3‰) and Oligocene (-9.0±0.3‰) are indistinguishable, suggesting no major change in mean annual precipitation in Saskatchewan across the transition. The δ13C values in Saskatchewan indicate the presence of arid ecosystems and are slightly higher than those in the US Great Plains, suggesting drier conditions at higher latitudes. With respect to oxygen isotopes, average (±1σ) perissodactyl enamel δ18O values (vs. V-SMOW) in the Eocene (19.8±2.0‰) and Oligocene (20.1±3.6‰) are also indistinguishable, suggesting no change in the δ18O of meteoric precipitation across the transition in Saskatchewan. Enamel δ18O variability is much larger in the Oligocene vs. Eocene, indicating a large increase in temperature seasonality. This increase in enamel δ18O variability is much larger than that recorded in the US Great Plains, suggesting that higher latitudes are more sensitive to major episodes of climate change with respect to temperature seasonality. Finally, our data indicate no major change in the Oligocene vs. Eocene latitudinal gradient in local water δ18O in North America, which suggests no change in mean annual temperature gradients across the transition. This result supports the hypothesis that ascribes the climate change of the transition to a drop in atmospheric pCO2 because climate models show that this mechanism produces uniform cooling at mid-latitudes. © 2014. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69125
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Earth Science, Utah Valley University, Orem, UT, United States; Royal Saskatchewan Museum, Regina, SK, Canada; Department of Geosciences, Boise State University, Boise, ID, United States; Department of Earth Sciences, Syracuse University, Syracuse, NY, United States
Recommended Citation:
Zanazzi A.,Judd E.,Fletcher A.,et al. Eocene-Oligocene latitudinal climate gradients in North America inferred from stable isotope ratios in perissodactyl tooth enamel[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,417