THE RELATIONSHIP BETWEEN P FE AND V/FE RATIOS IN HYDROTHERMAL PRECIPITATES AND DISSOLVED PHOSPHATE IN SEAWATER/

A strong positive relationship between the molar P/Fe ratio in fresh h ydrothermal Fe ferrihydrite precipitates and seawater-dissolved phosph ate has been demonstrated using samples from the Atlantic and Pacific Oceans. We ascribe this relationship to scavenging of dissolved phosph ate from seawater during the formation of hydrothermal Fe-rich particl es above hydrothermal vents. In contrast, molar V/Fe ratios in hydroth ermal particles are inversely correlated with dissolved phosphate. The se results indicate that inter-ocean variations in dissolved phosphate control the P/Fe and V/Fe ratios in hydrothermal Fe precipitates, one of the precursors of metalliferous sediment.