Particle geochemistry in the Rainbow hydrothermal plume, Mid-Atlantic Ridge

摘要: We report the analysis of 18 large volume (500-1500 L) in situ filtered samples particulate material from largest hydrothermal plume on Mid-Atlantic Ridge, overlying ultramafic-hosted Rainbow field at 36[deg] 14'N. Measured iron concentrations reach 614 nM. High Fe oxyhydroxides result extremely high concentration (~24 mM) and Fe/H2S ratio (~24) vent fluids, persist to least 10 km away site due advection with ambient along-axis flow. Two nine pairs pump deployments appear have intercepted buoyant or otherwise very young portion plume. These are characterized by anomalously (compared neutrally samples) Mg, U, chalcophile elements, low Mn, Ca, V, Y, rare earth elements (REE). Within plume, elemental distributions largely consistent previously observed behaviors: preferential removal conservative behavior oxyanions (P, U), continuous scavenging Y REE. This consistency is particularly significant light underlying differences fluid chemistry between other studied sites. Chalcophile preferentially removed order Cd>Zn>Co>Cu. Phosphorus/iron vanadium/iron ratios for global trends respect dissolved phosphate seawater. Comparison data sediments (Cave et al., 2002) indicates, however, that while P/Fe indeed constant V/Fe increase progressively early stage particles sediments. REE most a process during dispersion through water column