Climate in the Great Lakes Region Between 14,000 and 4000 Years Ago from Isotopic Composition of Conifer Wood
2006; Cambridge University Press; Volume: 48; Issue: 2 Linguagem: Inglês
10.1017/s0033822200066406
ISSN1945-5755
AutoresSteven W. Leavitt, Irina P. Panyushkina, Todd Lange, Alex C. Wiedenhoeft, Cheng Li, R.D. Hunter, John Hughes, Frank Pranschke, Allan F. Schneider, Joseph M. Moran, Ron Stieglitz,
Tópico(s)Archaeology and ancient environmental studies
ResumoThe isotopic composition of ancient wood has the potential to provide information about past environments. We analyzed the δ 13 C, δ 18 O, and δ 2 H of cellulose of conifer trees from several cross-sections at each of 9 sites around the Great Lakes region ranging from ∼4000 to 14,000 cal BP. Isotopic values of Picea , Pinus , and Thuja species seem interchangeable for δ 18 O and δ 2 H comparisons, but Thuja appears distinctly different from the other 2 in its δ 13 C composition. Isotopic results suggest that the 2 sites of near-Younger Dryas age experienced the coldest conditions, although the Gribben Basin site near the Laurentide ice sheet was relatively dry, whereas the Liverpool site 500 km south was moister. The spatial isotopic variability of 3 of the 4 sites of Two Creeks age shows evidence of an elevation effect, perhaps related to sites farther inland from the Lake Michigan shoreline experiencing warmer daytime growing season temperatures. Thus, despite floristic similarity across sites (wood samples at 7 of the sites being Picea ), the isotopes appear to reflect environmental differences that might not be readily evident from a purely floristic interpretation of macrofossil or pollen identification.
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