CGRG Bibliography of Canadian Geomorphology
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Author : Ali, A.A.; Loisel, J.; Ghaleb, B.; Garneau, M.; and Asnong, H.
Date : 2007.
Title : 210Pb radiometric dating of peat accumulation and environmental changes during the last centuries in taiga and boreal forests, Quebec, Canada.
Publication : CANQUA Ottawa 2007. Canadian Quaternary Association Conference, June 4-8, 2007. Carleton University, Ottawa, Ontario, Canada.
Issue :
Page(s) :
Abstract
The use of 210Pb to reconstruct recent peat accumulation represents an unusual and controversial issue. The principal limitations for using this radiometric method securely are irregular sedimentation rates and both biotic and abiotic perturbations that take place in the upper peatland horizons. In order to reconstruct environmental changes that occurred during the last centuries in the James Bay region (La Grande and Eastmain drainage basins), several peat cores were dated using the 210Pb method. Unexpected results testified that this technique can provide appropriate chronologies. In fact, in regard to radiocarbon dating and paleoenvionmental reconstructions carried out in the same sequences, accurate chronologies were established. An increase of peat accumulation rate at the top of all sequences, related to less compaction and variable decomposition at the acrotelm/catotelm contact was recorded with a homogenous pattern. Downwards into these sequences, potential impacts of the Neo-glacial and the Little Ice Age cooling events on the water-table fluctuations were also recorded. Failure in 210Pb results is related with the assumption that physical perturbations through peat accumulation might have been induced from variations of the water-table depth up to peat surfaces. In order to validate and secure 210Pb carried out on peat sediments, it is necessary to take into account possible compaction and density variations along cores. The combination of several dating methods (14C, 210Pb, 137CS and 241Am) may also allow to obtain more accurate chronologies and might therefore be useful to better understand paleoenvironmental changes deduced from recent peat sediments.
Bibliography of Canadian Geomorphology