ABSTRACT: Oxygen-isotope variations in the Malaspina and Saskatchewan Glaciers.

CGRG Bibliography of Canadian Geomorphology
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Abstract

Oxygan-isotope analyses of ice and firm from the Saskatchewan Glacier (Banff National Park, Alberta), Canada, and the Malaspina Glacier (St. Elias Mts.), Alaska, show that variations in O18/O16 ratios are likely to be of considerable value in glacialogical research. The general trend of O18/O16 ratios in ice along the centre flow line of Saskatchewan Glacier is a decrease from firn limit to terminus. This is interpreted as indicating that ice at successively lower points in the glacier tongue originated at progressively higher positions in the accumulation area, thus confirming Reid's early deductions concerning flow lines in a valley glacier. Ice in the glacier tongue has a higher average O18/O16 ratio than the 1953-1954 layer of firn in the accumulation area. This may be due to the fact that meltwater relatively rich in O18 percolating down from the surface has refrozen in the deeper firn, or it may possibly indicate a change to cooler climatic conditions within the last few hundred years. Ice samples from a transverse profile across Saskatchewan Glacier have higher O18/O16 ratios near the centre than near the margins. This occurs because the marginal ice comes from a higher altitude in the accumulation area. Seperate strata within Saskatchewan firn display large differences in oxygen-isotope ratios which are preserved to some degree in the ice tongue and may be useful in the identification of vestigial sedimentary layering. However, a high degree of homogenization can occur by the time the ice reaches the lower part of the glacier, as shown by a series of closely spaced samples of well-foliated ice with remarkably consistent oxygen-isotope ratios. In Malaspina Glacier, the oxygen-isotope ratios confirm a deduction made earlier as to the principal units composing this piedmont sheet. Ice that originates in the upper Seaward Basin has a higher O18/O16 ratio than material supplied from higher mountain slopes bounding that basin. Oxygen-isotope data also confirm an earlier interpretation to the effect that the intensely deformed and greatly thinned bands of ice in the outer part of Malaspina Glacier represent individual valley glaciers seperated by medial moraines. (8 figs., incl. maps, columnar secs.)

Bibliography of Canadian Geomorphology