Temporal Changes in Hydrothermal Fluid Chemistry

The first high-temperature submarine hydrothermal systems that were studied over time maintained very stable fluid composition. This was interpreted as evidence for equilibrium control of vent fluid composition.

Large changes over time in chemical composition of vent fluids were not seen until 1990, when hydrothermal systems affected by volcanic activity were first sampled and it became apparent that rapid and significant changes in the style of venting and fluid compositions occur immediately following an eruption (Haymon et al. 1993; Butterfield & Massoth 1994; Von Damm et al. 1995). Seafloor volcanic eruptions clearly have dramatic and interconnected consequences including formation of megaplumes (event plumes), microbiological blooms, and rapid evolution of the temperature and composition of vent fluids (Haymon et al. 1993; Embley & Chadwick 1994; Baker 1995; Baker et al. 1995; Embley et al. 1995; Lupton et al. 1995; Von Damm et al. 1995; Holden 1996). With the evidence accumulating from seafloor eruption events at North Cleft, the East Pacific Rise at 9 50 N, segment, and the EPR near 17 30 S (Auzende et al. 1994), it is possible to describe how hydrothermal systems change immediately following a volcanic event and to estimate how hydrothermal fluxes are affected. Data and observations from the Juan de Fuca sites have been used to construct a general model of hydrothermal response and chemical evolution of fluids following a volcanic event.

(Modified from Butterfield et al. 1997 Philosophical Transaction of the Royal Society, volume 355.) Response of hydrothermal systems to a volcanic event. Relative intensity of heat flux ( red line) and vent fluid concentrations of chloride (blue line), iron (dotted line), and hydrogen sulfide (thick line) over time. Systems evolve from a vapor-dominated, high heat flux stage accompanied by phase separation, through a transition to brine-dominated discharge, and eventually decay back toward zero heat flux and seawater composition. The following papers contributed to the formulation of this model: Butterfield and Massoth, 1994, Von Damm et al. 1995, Lupton 1995, and Baker 1995.