Compositional Changes Induced by Hydrothermal Alteration at the Red MountainAlunite Deposit, Lake City, Colorado

摘要

Red Mountain, on the eastern margin of the 23.1-Ma Lake City caldera (Hon, 1987),Lake City, Colo., hosts one of the largest replacement alunite deposits in the western United States (more than 70 million metric tons of alunite). Chemical analyses of 35 samples selected from both altered and fresh rocks from Red Mountain were analyzed to evaluate chemical changes within the major alteration assemblages. The paper briefly summarizes the geology of Red Mountain, presents the mass-balance data, and discusses the implications of these data with respect to mineralogic changes within the alteration assemblages.