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Abstract
Groundwaters from diamondiferous kimberlite pipes in the Kirkland Lake and Lake Timiskaming regions display unusual geochemical characteristics and signatures compared with groundwaters from the surrounding host rock. Reaction modeling was used to better constrain water-rock ratios, alteration mineralogy and groundwater geochemistry. A soil-zone Ca-HCO3 water from glacial till was reacted, using a reaction modeling program, with three different suites of minerals: a kimberlite suite, a felsic intrusive suite and a mafic intrusive suite. Decreasing pH and alkalinity with increasing water-rock ratios in model reactions with the kimberlite suite suggest that sampled groundwaters are from both the hypabyssal facies (high pH and alkalinity; low water-rock ratios) and the diatreme facies (low pH and alkalinity; high water-rock ratios). Exploration for kimberlites can benefit from the use of groundwater. Groundwater interaction with kimberlite rocks produces characteristic aqueous geochemical anomalies due to these low temperature serpentinization reactions. The identification of geochemical anomalies in the groundwaters down-flow of the kimberlite and the unusual mineral assemblages that may precipitate from these groundwaters may aid in the location of undiscovered kimberlites. (Abstract shortened by UMI.)
