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Genetic implications of halide enrichment near a Mississippi Valley-type ore deposit

Journal Article · · Econ. Geol.; (United States)
Analysis of host dolomite adjacent to the Buick lead-zinc-copper deposit, Viburnum Trend, southeast Missouri, by instrumental neutron activation (INAA) and X-ray fluorescence (XRF) has revealed large and distinct primary wall-rock enrichments of bromine and chlorine, respectively. The halide enrichment extends up to 250 ft from the deposit and is found in close association with trace element enrichments. The presence of 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. The Br/Cl ratios of the dolomite samples also display an asymptotic decrease with distance from the deposit. The elevated Br/Cl ratios of the rock samples and their soluble fractions 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 of the Buick mine and Viburnum Trend deposits evolved from bitterns which formed contemporaneously with an evaporite sequence. These bitterns subsequently underwent mixing with less saline waters prior to or during ore mineralization. 18 references, 3 figures, 2 tables.
Research Organization:
Brookhaven National Lab., Upton, NY
OSTI ID:
5309328
Journal Information:
Econ. Geol.; (United States), Journal Name: Econ. Geol.; (United States) Vol. 78; ISSN ECGLA
Country of Publication:
United States
Language:
English