100th Anniversary Special Paper: Metal Concentrations in Crustal Fluids and Their Relationship to OreFormation

摘要: A database of saline fluid compositions, including deep shield ground waters, sedimentary formation geothermal brines, and fluids from metamorphic igneous rocks veins, is used to explore the controls on metal concentrations in crustal fluids. There are no systematic differences between analyses sampled by drilling inclusions. Over wide range studied, temperature emerges as a dominant control Fe, Mn, Zn, Pb solution, although more limited data for Cu equivocal. Chloride concentration also important, with mole ratio metal/chloride (Me/Cl) remaining reasonably constant at over chlorinities all four metals considered detail. evidence significant transition-metal speciation increasing chloride nor low- high-temperature fluids, case complexes additional Cl may be important low temperature. Plots log Me/Cl versus 1/T transition each yield linear correlation, about five orders magnitude variation diagenetic magmatic temperatures. approximately two variability temperature, which probably arises large part variations pH. Limited low-salinity, CO2-rich indicate that they lie same trends, controlled salinity Order any chloride-dominated can predicted following equations (T K, ratios molar): (Fe/Cl) = 1.4 – (1,943/T) ± 1; (Mn/Cl) 0.55 (1,871/T) (Zn/Cl) =– (1,781/T) (Pb/Cl) –1.2 (1,533/T) 1. The results demonstrate strongly buffered through interactions (or melts) host them. Thus, major variables influencing only truly independent. The plots show metal-rich arise equilibration chloride-rich waters normal silicate rocks. Saline attain extremely high metals, have clear ore-forming potential, do brines deep, hot basins; cooler basins not permit such base attained. this study emphasize importance distribution cycling crust deposits; it often ore primary anomaly.