Evidence of Quaternary climatic variations in a sequence of loess and related deposits at Birch Creek, Alaska: implications for the stage 5 climatic chronology


McDowell, P.F. and Edwards, M.E. (2001) Evidence of Quaternary climatic variations in a sequence of loess and related deposits at Birch Creek, Alaska: implications for the stage 5 climatic chronology. Quaternary Science Reviews, 20, (1), 63-76. (doi:10.1016/S0277-3791(00)00131-1).

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Description/Abstract

A 45 m outcrop of Quaternary sediments on Birch Creek, near Circle, Alaska, reveals a record of #uctuating environmental
conditions that probably spans several glacial}interglacial cycles. From base to top the deposits are forested #oodplain (warm),
colluvium with ice wedges (cold), forest soil (warm), loess (cold), paleosol containing Old Crow Tephra (OCt) (cool-to-warm), loess
(cold), lacustrine (very warm), loess (cold), and modern forest soil (warm). Resolution of the paleoclimatic history associated with the
OCt event is critical to understanding the nature of stage 5 in the western North American Arctic. Application of recent age estimates
for the OCt tephra (ca. 140,000 yr BP) to the Birch Creek section would indicate that either (i) the tephra/paleosol dates from the 6/5.5
transition, a strongly developed glacial interval occurred within stage 5, and the overlying very warm interval occurred in 5.3 or 5.1, or
(ii) the tephra was deposited during a `non-Milankovitcha warming event late in stage 6. A paleoclimate chronology provides an
alternative interpretation, (iii), in which the tephra/paleosol corresponds to stage 6 or even stage 7, the overlying loess to stage 6, and
the lake sediments to all or part of stage 5, but the OCt is older than 140,000 yr BP. Chronologies (ii) and (iii) imply a very warm
beginning to stage 5, consistent with paleoclimate model simulations and data from other regions. ( 2000 Elsevier Science Ltd. All
rights reserved.

Item Type: Article
ISSNs: 0277-3791 (print)
Related URLs:
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
G Geography. Anthropology. Recreation > GB Physical geography
Divisions: University Structure - Pre August 2011 > School of Geography > Environmental Processes and Change
ePrint ID: 55307
Date Deposited: 01 Aug 2008
Last Modified: 27 Mar 2014 18:38
Contact Email Address: M.E.Edwards@soton.ac.uk
URI: http://eprints.soton.ac.uk/id/eprint/55307

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