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Evidence for Multiple, Episodic, Mid-Holocene Hypsithermal Recorded in Two Soil Profiles along an Alluvial Floodplain Catena, Southeastern Tennessee, USA
Quaternary Research (2008)
  • Steven G. Driese, Baylor University
  • Zheng-Hua Li, University of Tennessee - Knoxville
  • Larry McKay, University of Tennessee - Knoxville
Abstract
Floodplain soil–paleosol successions are valuable archives for reconstructing Pleistocene–Holocene climate changes but have been relatively unstudied in the southern Appalachian region. Two soil profiles on a small floodplain in southeastern Tennessee, USA were described and sampled in detail using both pedological and geological approaches, including stable carbon isotope analysis of soil organic matter (SOM). Correlation between the 2 profiles was constrained by uncalibrated AMS 14C ages of bulk humates, and using SOM δ13C values, both mobile and immobile elements. Four distinct 2.5–4‰ shifts towards less negative δ13C values for SOM suggest 300-yr cyclicity and transient warmer and drier climate events, with either water-stressed C3 vegetation or as much as 35% C4 plants present during the mid-Holocene. These postulated multi-episodic drier climate conditions have never before been documented in the southern Appalachian region and are tentatively correlated with mid-Holocene warming and drying in the eastern US, the nearly time-equivalent mid-Holocene events documented in Texas, the US High Plains and in the Gulf of Mexico. High rates of floodplain sediment accumulation (0.5–3 mm/yr), high clay content and maintenance of poorly drained soil conditions favor preservation of high-resolution climate archives in floodplain deposits by inhibiting oxidation and translocation of organic C.
Keywords
  • Paleoclimate; Mid-Holocene soils; Stable carbon isotopes; Southeastern US; Floodplains
Disciplines
Publication Date
March, 2008
Citation Information
Steven G. Driese, Zheng-Hua Li and Larry McKay. "Evidence for Multiple, Episodic, Mid-Holocene Hypsithermal Recorded in Two Soil Profiles along an Alluvial Floodplain Catena, Southeastern Tennessee, USA" Quaternary Research Vol. 69 Iss. 2 (2008)
Available at: http://works.bepress.com/larry_mckay/8/