Late Wisconsinan and holocene depositional chronologies of aeolian sands in central and northern Alberta: implications for deglaciation patterns and environmental evolution

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The landscape of the province of Alberta features accumulations of wind deposited sands that occur in many places as fossil dune structures. Over the last two to three decades, a technique called luminescence dating has been developed by which sand grains from such landforms can be made to glow in a laboratory setting as a means of deciphering the amount of time that has elapsed since the sands were last buried. Investigations performed on dune structures from southern Alberta using such methods have demonstrated that the dune structures there have not remained fixed since their first emplacement. Instead, the sands have been remobilized at various times over the last 10 000 years. These episodes of reactivation have been linked to variations in climate. Contrastingly, only a limited number of studies have been carried out on dune sequences from central Alberta and results obtained suggest the dune structures in the region range in age between 15 700 and 10 500 years before present. No study to date, however, has constrained the duration over which deposition by wind occurred at any one location in central Alberta such that it remains unknown when precisely the activation by wind began, when it ended or whether it was recurrent. This study will collect samples from dune structures in central and northern Alberta containing depositional sequences longer than any investigated in the area to date. The collected samples will be dated using luminescence dating techniques to provide depositional chronologies. The results will be compared with data from southern Alberta as well those from across the Canadian prairies to elucidate on patterns in environmental change over the last 20 000 years. Such medium range data on climate change will help put the current global warming debate into context. In addition, sediments from lower sections of the dune structures should provide age constraints for the withdrawal of ice sheets from western Canada at the end of the last glacial period. Hence, such ages will be used to address the long standing question of whether an inland 'ice-free corridor' did exist in western Canada around about 14 000 years ago or earlier that would have been used by the first Americans to migrate south to the mid latitudes.