FY 1994

Trace metals in hydrothermal solutions from Cleft Segment on the southern Juan de Fuca Ridge

Trefry, J.H., D.B. Butterfield, S. Metz, G.J. Massoth, R.P. Trocine, and R.A. Feely

J. Geophys. Res., 99(B3), 4925–4936 (1994)

Concentrations of trace metals in Fe- and Cl-rich hydrothermal solutions from the southern Juan de Fuca Ridge (SJFR) have been determined and corrected for residual precipitates formed in the sampler. Precipitate corrections for Ag, Cd, Cu, Mo, Pb, Sb, and Zn were variable, contributing an average of 20% to total solution concentrations whereas corrections for Co averaged less than 5% and essentially no corrections were required for Fe and Mn. Values for Cu, Co, and Mo in these solutions showed a strong dependence on temperature with sharp decreases in concentrations as temperatures decreased to less than 320°C. In addition, and unlike most other metals studied, all vent fluids from the SJFR were almost completely depleted in Mo relative to seawater values of about 110 nmol kg. In contrast to the Cu-Co-Mo group, concentrations of Ag, Cd, Sb, and Pb correlated well with those for Zn and are presumed to follow a distribution that is influenced less by temperature over the 246 to 332°C range encountered in this study and more by the combined chemical processes that control Zn levels along the transport pathway from the deep reaction zone to the vent orifice.