Showing papers by "Gary P. Klinkhammer published in 1985"

Hydrothermal manganese plumes in the Mid-Atlantic Ridge rift valley

Abstract: The concentration of dissolved manganese in sea water can be used as a chemical tracer of hydrothermal activity on the underlying sea floor. Here we present vertical profiles of seawater manganese concentrations above the rift valley of the Mid-Atlantic Ridge (MAR). The values obtained indicate the presence of plumes that are presently active generated by hydrothermal vents in the rift valley. These plumes are confined to the rift valley and do not spill over into the adjacent deep ocean basins. Differences between them suggest that there are at least five hydrothermal sources along this 1,700-km-long section of mid-ocean ridge.

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

Abstract: 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 µg/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 µg/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 µg of total suspended matter/1 found along the rift valley.