Host dolomite, Buick lead-zinc-copper deposit, Viburnum Trend, Missouri. Halide enrichment extends up to 250 ft from the deposit and is in close association with trace element enrichments. The Br and Cl enrichment zone is strong additional evidence that the ore-forming solutions of the Viburnum Trend were metal-rich Na-Cl brines. Br/Cl ratios also display an asymptotic decrease with distance from the deposit. The Br/Cl ratios of the whole-rock samples from within and near the deposit and from the water soluble leachate reveal that the ore-forming solutions were enriched in Br relative to seawater. The elevated Br/Cl ratios indicate that the ore-forming solutions were initially formed from the evaporation of seawater past the point of halite precipitation. This implies that the ore-forming solutions evolved from bitterns which formed contemporaneously with evaporite sequence. These bitterns subsequently underwent mixing with less saline waters prior to or during ore mineralization.--Modified journal abstract.