Deuteric alteration within large compound ignimbrite cooling units of east-central Nevada redistributed major elements in reactive volcanic glass, creating pronounced vertical chemical variations. K-Na exchanges and Mg and Fe redistribution were the most distinctive deuteric alteration phenomena. Weathering, which is superimposed over the deuteric alteration pattern, affected the more porous zones primarily by leaching sodium and causing growth of Ca (super -) montmorillonite. Local hydrothermal fluids added potassium and removed sodium in the plagioclase phenocrysts and volcanic glass.