Strontium isotopic constraints on the origin of ore-forming fluids of the Viburnum Trend, southeast Missouri

Journal Article · Wed May 01 00:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90317-X· OSTI ID:6140284

Brannon, J C; Podosek, F A ^[1]; Viets, J G; Leach, D L; Goldhaber, M ^[2]

---

1. Washington Univ., St. Louis, MO (United States)
2. Geological Survey, Denver, CO (United States)

The authors have measured {sup 87}Sr/{sup 86}Sr and Rb and Sr concentrations in several minerals, primarily sulfides, spanning the paragenesis of hydrothermal mineralization in the Viburnum Trend in southeast Missouri. Separate measurements were made for fluid inclusions opened by crushing or thermal decrepitation and for the solids. In several cases {sup 87}Sr/{sup 86}Sr ratios are different (higher) in the solids than in the fluid inclusions. The authors investigated the possibility that either type of sample gives spurious results, e.g., that the fluid inclusions are secondary or contaminated by host dolomite, or that Sr in the solids reflects a detrital rather than an authigenic source. Consideration of mass balance, overall solute chemistry, and examination of non-sulfide dissolution residue, however, suggests that both types of sample reflect primary fluid Sr composition. The authors thus adopt the working hypothesis that Sr isotopic composition in fluids at the time of hydrothermal mineralization was highly variable. The observed results for the Viburnum Trend do not conform well to expected trends for Mississippi Valley-type (MVT) mineralization based primarily on analyses of gangue carbonates, barite, and fluorite. Fluid inclusion Sr in some of the Viburnum Trend samples is more radiogenic than in the host dolomite but only moderately so; in other samples, notably main-stage octahedral galena, fluid inclusion Sr composition is within the range observed for the host dolomite. in contrast, Sr in some of the sulfides is very radiogenic, much more so than previously reported for MVT minerals, and is very radiogenic early in the paragenesis (pyrite, chalcopyrite, sphalerite), less radiogenic during main-stage ore deposition, and again more radiogenic in later paragenetic stages.

• OSTI ID: 6140284
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 55:5; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH ISOTOPES
AQUIFERS
BARITE
BETA DECAY RADIOISOTOPES
CARBONATE MINERALS
CHEMICAL COMPOSITION
CHEMISTRY
COMPARATIVE EVALUATIONS
DEVELOPED COUNTRIES
DOLOMITE
ELECTRON CAPTURE RADIOISOTOPES
EVALUATION
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FEDERAL REGION VII
FLUORITE
GALENA
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOTHERMAL SYSTEMS
HALIDE MINERALS
HOURS LIVING RADIOISOTOPES
HYDROTHERMAL SYSTEMS
INCLUSIONS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
LEAD ORES
MINERALIZATION
MINERALS
MISSOURI
NORTH AMERICA
NUCLEI
ORES
ORIGIN
PARAGENESIS
PETROGENESIS
RADIOISOTOPES
STABLE ISOTOPES
STRONTIUM 86
STRONTIUM 87
STRONTIUM ISOTOPES
SULFATE MINERALS
SULFIDE MINERALS
USA
ZINC ORES