CGRG Bibliography of Canadian Geomorphology
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Author : Duval, T.P.; Waddington, J.M.; and Branfireun, B.A.
Date : 2006.
Title : Linking marl flat formation and water table position in a calcareous fen.
Publication : Annual Scientific Meeting of the Canadian Geophysical Meeting, May 14-17, 2006. Banff Centre, Banff, Alberta. Abstracts Volume.
Issue :
Page(s) : 40-41.
Abstract
Calcareous fens are unique wetland systems dominated by groundwater input high in minerals and carbonates, exhibiting high species richness, and supporting regionally rare vegetation. These ecosystems typically are associated with zones of calcium carbonate precipitation, referred to as marl flats. However, the hydrological controls on the development of marl flats are poorly understood. The extent of marl accumulation was examined in a small calcareous fen in Puslinch Township, Ontario through coring and loss-on-ignition of peat profiles. The main source of water to the fen is a carbonate-rich stream which bisects the site. The present-day marl flat is hydrologically disconnected from this main source area, contrary to what has been found at other sites presented in the literature. Weekly measurements were taken from a network of wells in 2005 to document the spatial variability in water table fluctuation across the fen. Water table fluctuation increased with increasing distance from the stream, from 9 cm (3 cm below ground, 6 cm above) to a maximum of 25 cm (9 cm below ground, 16 cm above) in the area of the current marl flat. Carbonate content in the surface zone of the sediments followed this trend of increasing water table fluctuation, from a minimum of ~ 2 % to a maximum of > 20 %. More important than the range of fluctuation however, is the duration of elevated water table position, with high water tables promoting carbonate precipitation through increased carbon dioxide degassing. Thus, the zone of maximum difference in seasonal water table position is also the site of marl flat formation due to the greater duration of standing water. The implications of these findings to rehabilitation of abandoned limestone quarry sites into calcareous fens will be discussed.
Bibliography of Canadian Geomorphology