Geochemical Mass Balances and Cycles of the Elements

Abstract

The role of hydrothermal convection associated with volcanism in the chemical transport in the Earth’s crust has been known for a long time. The focus until fairly recently, however, had been on processes observed at volcanic sites on land. It was known that the dominant source of water emanating from hot springs and fumaroles was of meteoric origin and that despite the obvious relation to deep sources of magma, juvenile water was virtually impossible to identify at these sites. Precipitation permeated the surface and, as ground water, provided both the reaction solution and the transporting medium for elements released by the hydrothermal alteration of rocks. Many of these chemical species were then deposited around the vents of fumaroles, geysers and hot springs resulting in the characteristic deposits seen in many places. Deposition also took place within the cooler environment of the upper aquifer.