CGRG Bibliography of Canadian Geomorphology
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Author : Fairchild, I.J.; Bradby, L.; Sharp, M.; and Tison, J.
Date : 1994,
Title : Hydrochemistry of carbonate terrains in alpine glacial settings.
Publication : Earth Surface Processes and Landforms
Issue : 19(1):
Page(s) : 33-54.
Abstract
Nearly 200 analyses of meltwaters, ice and snow from three alpine glacial sites in carbonate terrain are summarized and discussed in terms of sources of solutes and kinetic controls on the progress of weathering reactions. Most data derive from the Swiss Glacier de Tsanfleuron which is based on Cretaceous and Tertiary pure and impure limestones. Two other sites (Marmolada, Italian Dolomites and the Saskatchewan Glacier, Alberta) are based on a mixed calcitic-dolomitic substrate. Most solutes originate from carbonate dissolution; moreover, where pyrite is present its oxidation supplies significant sulphate and forces more dissolution of carbonate. The ratios Sr super(2+)/Ca super(2+) and Mg super(2+)/Ca super(2+) are much higher in Tsanfleuron meltwaters than local bedrock, a phenomenon that can be reproduced in the laboratory at small percentages of dissolution. These anomalous ratios are attributed to incongruent dissolution of traces of the metastable carbonates Mg-calcite and aragonite. These phases also provide Na super(+) to solution. K super(+) is argued to originate mainly by ion-exchange on clays with solute Ca super(2+). Quartz and very minor feldspar dissolution are also inferred. Locally enhanced input from atmospheric sources is recognized by high Cl super(-) and associated Na super(+). The progress of weathering reactions has been evaluated by the trends in the data, computer modelling and some simple laboratory experiments. The most dilute samples show a trend towards removal of CO sub(2) to low partial pressures (c.10 super(-5.5) atmospheres), reflecting initially rapid carbonate dissolution and relatively slow dissolution of gaseous CO sub(2). Later addition of atmospheric CO sub(2) or acid from pyrite oxidation allows further carbonate dissolution, but solutions show a wide range of saturations, and CO sub(2) pressures as high as 10 super(-2 multiplied by 2) where pyrite oxidation is important
Bibliography of Canadian Geomorphology