Iron and copper enrichment of suspended particles in dispersed hydrothermal plumes along the mid‐Atlantic Ridge

Particulate Fe and Cu concentrations are used in conjunction with dissolved Mn values to identify hydrothermal venting at several sites along the Mid‐Atlantic Ridge (MAR). In dispersed hydrothermal plumes, as defined by dissolved Mn anomalies, suspended matter Fe and Cu values were as high as 15.8% and 1100 µ g/g respectively, relative to Al at 1.7%. Suspended matter Fe and Cu values correlate well with dissolved Mn concentrations, tracing the intensity of dispersed plumes. In contrast with Fe and Cu, particulate Mn values in vent plumes were low at 700‐1200 µ g/g. Calculated (Al + Fe + Mn)/Al ratios for MAR particles increase with increasing dissolved Mn concentrations. This ratio is used to estimate the percent hydrothermal component of the suspended matter. These sensitive tracers identify a 2‐20% hydrothermal contribution to the 10 ± 2 µ g of total suspended matter/1 found along the rift valley.