Cryogenic Brines and Evaporites

The increase of the salinity of cryogenic brines causes minerals to precipitate depending on the chemical composition of the brine and the solubility of the 

Subglacial deposits of crdcite and aragonite from previously ice-covered areas in the world have been described by Bauer (1961), Ford et al. (1970), Page (1971), Magaritz (1973), HaUet (1976), Bjaerke and Dypvik (1977), Hanshaw and HaUet (1978), Peterson and Moresby (1979), HiUaire-Marcel et al. (1979), Lemmens et al. (1982), Souchez and Lenunens (1985), and Aharon (1988). 

The evaporite minerals described by Fitzpatrick et al. (1990) are noteworthy because they include salts of boron and potassium which were identified by x-ray diffraction supplemented by chemical analyses. The results, compiled in Table 17.11, indicate that the minerals are primarily carbonates, bicarbonates, sulfate, and borates of sodium. These salts have also formed in Searles Lake and Deep Springs Lake in California and in Lake Magadi in Kenya. The brines in these lakes 

Therefore, the brine probably formed from a mixture of meltwaters rather than from locally derived meltwater. The carbon dioxide that is required for the precipitation of nahcolite (Eugster 1966) may have originated either from atmospheric carbon dioxide that was released by melting of basal ice or by dissolution of carbonate rocks. 

The carbon-14 dates of two samples of nahcolite on the Lewis Cliff ice tongue are concordant and have a mean value of 22,985 518 years. However, the carbon-14 dates of three additional nahcolites are discordant and have values of 9,960 100, 34,470 710, and 37,730 1,060 years. Fitzpatrick et al. (1990) also reported uranium-series disequilibrium dates of nahcolites based on the decay of to Th (Faure and Mensing 2005 Section 20. Ic). These dates range from 6,100 100 to 150,000 4,000 years and differ significantly from the carbon-14 dates. For example, the two nahcolite samples that yielded a combined 

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