Evaporite encrustations and sulphide oxidation products from the southern Antarctic peninsula.

White evaporite encrustations collected from 66 sites scattered over 30 000km2 of S.Antarctic Peninsula are dominantly gypsum and calcite, and subordinate aragonite and thenardite. Natrojarosite occurs as locally developed yellow surface stains on c30% of the white encrustations examined. Water, which forms by the melting of snow blown into cracks in highly fractured rocks by ground blizzards, dissolves soluble ions from minerals in these rocks as it percolates into them. The white encrustations appear to be deposited when this water later rises to the surface by capillary action and evaporates.-from Author Antarctica chemical weathering evaporites sulphide oxidation.