James, R.H., Elderfield, H. and Palmer, M.R.
The chemistry of hydrothermal fluids from the Broken Spur site, 29°N Mid-Atlantic ridge
Geochimica et Cosmochimica Acta, 59, (4), . (doi:10.1016/0016-7037(95)00003-I).
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Hydrothermal fluids have been collected from three high temperature (360–364°C) vents from Broken Spur (29°10.08?N, 43°10.46?W; water depth ? 3100 m). This is only the fourth site on a slow spreading ridge from which such fluids have been collected. Compared to other vent sites, the hydrothermal fluids are enriched in Li (1035 ?M) and have lower dissolved Mn (?250 ?M) and Sr (43 ?M) concentrations. The boron isotope systematics indicate that substantial removal (>50%) of seawater B has occurred in the low-temperature portion of the hydrothermal convection cell. In addition, low temperature removal of seawater Sr is ?10% greater at Broken Spur compared to similar vent sites in the Pacific where spreading rates are faster. A low Eu anomaly (11 ± 3) and a View the MathML source ratio (10.8) intermediate between pristine and weathered basalt suggest that the vent fluids have interacted with a component of basalt that has previously undergone low-temperature weathering. the fluids are 14% depleted in Cl relative to seawater. Supercritical phase separation appears to be the only reasonable process that may account for the fluid depletion.
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