A study of strontium isotopes in lakes and surficial deposits of the ice-free valleys, southern Victoria Land, Antarctica

The ice-free valleys of southern Victoria Land, Antarctica, contain saline lakes including Kale Vanda in Wright Valley and Lake Bonney in Taylor Valley. The source of the salts dissolved in the brines has not yet been identified. Strontium in water-soluble salts of soil samples in Wright Valley has 87Sr/86Sr ratios ranging from 0.7119 to 0.7157 with an average of 0.7144+-0.0008 (1 sigma). This value is very similar to the 87Sr/86Sr ratio of brines in Lake Vanda (87Sr/86Sr=0.7149+-0.00017), but differs significantly from the 87Sr/86Sr ratios of seawater (0.7094+-0.00012) and basaltic rocks of the McMurdo Volcanics (0.7044+-0.00046). The Sr in Lake Vanda therefore could not have originated from seawater or from volcanic rocks of the area, but may have been derived by chemical weathering of the igneous and metamorphic rocks exposed in Wright Valley. The 87Sr/84Sr ratios of Lake Bonney are invariant with depth and average 0.7130+-0.00014 (1 sigma). (Auth.)