Studies on Evaporite Minerals from Dry Valley, Victoria Land, Antarctica

Abstract

The areal and vertical distributions of evaporite minerals in the Taylor Valley and the Wright Valley were studied with X-ray diffraction techniques to disclose the origins of salts. Halite, sylvite. thenardite. mirabilite. Gypsum, calcite, aragonite, trona, thermonatrite, monohydrocalcite, soda niter, bloedite, and drapskite were identified in specimens on the ground surface, and calcite, fluorite, laumontite, chahay.ite. antarcticite, and chlorite in core samples. In general, carbonate minerals predominate in the Taylor Valley, while sulphate minerals, except thenardite, predominate in the Wright Valley. Halite and thenardite are widespread in both areas. Trona, thermonatrite, and monohydrocalcite are found exclusively in the eastern Taylor Valley, and soda niter, bloedite, and drapskite in the Wright Valley. There is a general trend for sulphate minerals to be concentrated in elevated areas, and carbonate minerals in low areas. From a comparison of the distribution of these salts and the chemical composition of lake water in the area, it seems that the main sources of salts distributed in the Taylor Valley and the Wright Valley are of marine and/or wind-transported origins, and that based on the nature of minerals from core samples, a small amount of salts is formed from hydrothermal solution.