Volume 10, Number 4 (1983)
Articles

The Redox State of Iron: A Powerful Indicator of Hydrothermal Alteration

Paul A. Studemeister
Dunraine Mines Ltd., Toronto, Ontario.
Published November 11, 1983
How to Cite
Studemeister, P. A. (1983). The Redox State of Iron: A Powerful Indicator of Hydrothermal Alteration. Geoscience Canada, 10(4). Retrieved from https://journals.lib.unb.ca/index.php/GC/article/view/3355

Abstract

The redox state of iron, (Fe +2/Fet), in rocks is a useful Indicator of hydrothermal alteration. In general, rocks are resistant to shifts in (Fe +2/Fet) unless large volumes of fluid or high concentrations of exotic reactants such as H2 or O2 are present. The earth's surface in equilibrium with the atmosphere is an oxidizing environment; surface waters carry in solution O2 plus SO4-2. Laboratory experiments conducted at high temperatures reveal that water in the presence of ferrous minerals tends to dissociate and yield free hydrogen. At depths exceeding a few kilometres, waters are hot and reducing with H2 H20 = 1 30 to 1/60. In a hydrothermal convection cell, rocks along the descending limbs will be oxidized whereas rocks along the ascending limbs will be reduced by the circulating water.