The potential of perennial cave ice in isotope palaeoclimatology |
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| Authors: | CHARLES J YONGE WILLIAM D MACDONALD |
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| Institution: | Charles J. Yonge and William D. MacDonald, Alberta Karst Consulting, 1009 Larch Place, Canmore, Alberta T1W 757, Canada. E-mail: |
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| Abstract: | Perennial ice from caves on and to the east of the Canadian Great Divide yield δ18O and δD values, which are unusually high measurements when compared with the average precipitation for the region. Furthermore, these ice data fall below and along lines of lower slope than the Global Meteoric Water Line. To explain the observed relationships, we propose the following process. A vapour-ice isotopic fractionation mechanism operates on warm-season vapour when it precipitates as hoar ice on entering the caves. The subsequent fall of hoar to the cave floor through mechanical overloading, along with ice derived from ground-water seepage (with a mean annual isotopic composition), results in massive ice formation of a mixed composition. This mixed composition is what is observed in the characteristic relationships found here. Such findings suggest that a warm versus cold climate interpretation for ancient cave ice may be the opposite of that found in the more familiar polar and glacial ice cores. |
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