ABSTRACT: Timing and significance of sandsheets deposition, Yukon River, Western Yukon.

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

Several eolian sandsheets can be found on the banks of the Yukon River. They are numerous and well exposed between Fortymile River and Eagle (Alaska). These sub-horizontal deposits occur on fluvial or glaciofluvial gravel and the thickness varies from less than one meter to eight meters. These sandsheets range from well stratified to massive fine-medium sand and can be interstratified with thin silty beds. Sharply defined parallel and low-angle laminations are present, that formed by the migration of low-amplitude wind ripples. They are associated with fluvial deposits and the sand supply is from Yukon River sediments. Their spatial distribution is probably controled by topography and their aggradation may correspond to the sparse vegetation and the strength of paleowinds. The moisture availability may also contribute to their formation. These sandsheets, also called coversands, are inactive now and have been deposited during a relatively short period of time at the end of the Pleistocene. Their development results from unique climatic and environmental conditions that prevailed towards the end of the Pleistocene. The objective of this study is a) to use infrared simulated luminescence (IRSL) and radiocarbon dating methods to constrain the timing of their formation and b) to document those depositional processes that were active along the Yukon River at this time. Statistical IRSL parameters confirm their eolian origin and are coherent with the ca 12-13 ka range deduced from preliminary radiocarbon dating.

Bibliography of Canadian Geomorphology