CGRG Bibliography of Canadian Geomorphology
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Author : Froese, D.G.; Hein, F.G; Barendregt, R.W.; Duk-Rodkin, A.; Enkin, R.; Baker, J.; and Smith, D.G.
Date : 1997
Title : Sedimentology and paleomagnetism of Pliocene-Pleistocene lower Klondike valley terrace sediments, west-central Yukon.
Publication : 8th Biennial Meeting of the Canadian Quaternary Association, Program with Abstracts, May 22-25, 1997, Montreal, Quebec. Edited by: M.A. Bouchard. University du Quebec a Montreal, Montreal
Issue :
Page(s) : 24.
Abstract
The lower Klondike River valley and its gold-bearing tributaries, Bonanza and Hunker Creeks, west-central Yukon, contains some of the best preserved and exposed Pliocene to early Pleistocene sediments in the Canadian Cordillera. In this study, detailed sedimentologic and paleomagnetic evidence is used to present a reconstruction of depositional environments correlated to the geomagnetic polarity time scale. In Pliocene pre-glacial times, gold bearing tributaries of the Klondike River, Bonanza and Hunker Creeks, deposited the White Channel Gravel as braided river alluvial fans with repeated cycles of aggradation and incision during the late Gilbert (?) and Gauss chrons. Climatic cooling in the late Pliocene resulted in White Channel aggradation and first evidence of periglacial conditions (ice wedge growth). Synchronous with alluvial aggradation in the unglaciated tributaries, and interfingering with distal upper White Channel Gravel, the Klondikewashed gravels record the first proglacial outwash in the Klondike valley during the late Gauss (magnetically normal >2.6 Ma). This outwash can be traced southeast to the Tintina Trench and was likely a result of the first late Pliocene advance of the northern Cordilleran Ice Sheet. In the Pleistocene, incision and subsequent aggradation of the Klondike valley resulted in an intermediate terrace with three successive depositional environments: (1) a lowermost interglacial wandering gravel bed river sequence; (2) deposition of a proximal braided river assemblage, indicating aggradation during a pre-Reid glacial event followed by incision and abandonment of the terrace level; and (3) beginning of loess deposition. Paleomagnetic results of these previously unreported loess and re-worked loess sediments indicate deposition through much of the Matuyama (2.6 - 0.78 Ma) and Brunhes (<0.78 Ma) chrons, suggesting the dominance of katabatic winds inthis area of Beringia during the early to middle Pleistocene. By Reid time (ca. 200 ka) the lower Klondike River and its tributaries were near their present levels.
Bibliography of Canadian Geomorphology