Late Quaternary environments of the Waco Mammoth site, Texas USA

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• 作者：Lee Nordt^a ; ^{lee_nordt@baylor.edu" class="auth_mail" title="E-mail the corresponding author} ; John Bongino^b ; Steven Forman^a ; Don Esker^a ; Anita Benedict^c
• 关键词：Mammoth ; Catastrophic ; Brazos River ; Pleistocene ; Alluvium
• 刊名：Quaternary Research
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：84
• 期：3
• 页码：423-438
• 全文大小：3070 K

文摘

The Waco Mammoth Site (WMS) in central Texas contains the remains of the largest mammoth herd (Mammuthus columbi) in North America that died in a single catastrophic event. Most mammoths at the site died on a gravel bar of the ancient Bosque River adjacent to a collapsing tributary wall. However, the timing and cause of death of the 26 mammoths documented to date are controversial. The objectives of this research are to: describe and interpret the alluvial stratigraphy and infer the cause of death, employ optically stimulated luminescence (OSL) dating to determine the timing of death, and analyze stable C isotopes of pedogenic carbonate to infer local plant communities, dietary habits, and summer temperatures. Dating of quartz from seven sediment samples by OSL places the death event to a weighted mean of 66.8 ± 5.0 ka. The site is coeval with Marine Oxygen Isotope Stage 4, consistent with our reconstructed mean July temperatures ~ 4°C cooler than today based on a buried soil isotopic transfer function. Our buried soil isotopic interpretation of a dominance of C₃ plants is contrary to previous studies of mammoth tooth enamel at the site suggesting a dietary preference for warm season grasses (C₄).