Formation of East Tennessee, Knox Mississippi Valley-Type (MVT) deposits by hydrothermal-thermochemical sulfate reduction/replacement interstratal evaporite karstification

Conference · Mon Mar 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5075048

Furman, F C ^[1]

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1. Univ. of Missouri, Rolla, MO (United States). Dept. of Geology and Geophysics

The East Tennessee Knox MVT deposits are hydrothermal-thermochemical sulfate reduction (TCSR) and replacement interstratal evaporite karst bodies. The main MVT mineralized breccias occur between 600--850 ft. below the unrelated post-Knox unconformity. Halite casts, gypsum molds, calcite pseudomorphs after evaporites, and bedded anhydrite occur in the Knox. The bedded anhydrite is correlatable with breccias filled with anhydrite, hydrocarbons, and MVT mineralization. The breccias contain floating fragments with snow-on-roof structure. Published sulfur isotopes of anhydrite and sphalerite ([delta][sup 34]S [approx]26--35[per thousand]) have a similar range. Sphalerite mineralization occurs beneath, the Holston seal, and fluorite and barite occurs where the seal is absent. Published fluid inclusion chemistry shows that sphalerite was deposited by fluids rich in CO[sub 2], hydrocarbons, and calcium poor, whereas fluorite is the opposite. Fluid inclusion Th and Tm data for sphalerite and fluorite are interpreted as forming by hydrothermal-TCSR and replacement of Knox anhydrite respectfully. Peritidal Knox anhydrite and organic rich sediments formed on paleohighs above uplifted basement blocks. Hydrothermal metalliferous basin brines initiated simultaneous anhydrite solution-subsidence-brecciation beneath impermeable chert beds. TCSR of the anhydrite by hydrocarbons trapped beneath the Holston seal precipitating sphalerite. Ba and F replaced the anhydrite forming barite and fluorite, where there was no hydrocarbons due to the lack of a seal.

• OSTI ID: 5075048
• Report Number(s): CONF-9303210-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:3; Conference: 27. annual Geological Society of America (GSA) North-Central Section meeting, Rolla, MO (United States), 29-30 Mar 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ANHYDRITE
HYDROTHERMAL ALTERATION
BARITE
CHEMICAL COMPOSITION
HYDROTHERMAL SYNTHESIS
FLUORITE
GEOLOGIC DEPOSITS
MINERALIZATION
ORIGIN
SPHALERITE
TENNESSEE
ZINC ORES
DEVELOPED COUNTRIES
HALIDE MINERALS
MINERALS
NORTH AMERICA
ORES
SULFATE MINERALS
SULFIDE MINERALS
SYNTHESIS
USA
580000* - Geosciences