The significance of Rb-Sr glauconite ages, Bonneterre Formation, Missouri; Late Devonian-Early Mississippian brine migration in the midcontinent
- Geological Survey, Denver, CO (USA)
- Florida State Univ., Tallahassee (USA)
Rb-Sr mean model ages of 370 {plus minus} 10 Ma for glauconites from the Cambrian lower Bonneterre Formation in southern and central Missouri are in excellent agreement with a Rb-Sr isochron age of 359 {plus minus} 22 Ma for glauconites from the Magmont mine (Viburnum Trend) in the southeast Missouri lead district. The lower Bonneterre and Magmont mines ages probably reflect isotopic resetting, most likely associated with dolomitization and/or Mississippi Valley-type ore formation in the southeast Missouri lead district. The temporal relation between widespread dolomitization and ore formation in Missouri is unclear, but mounting evidence for two Devonian disturbances permits the following interpretation: (1) a Devonian timing (380-400 Ma) for widespread dolomitization, and (2) a Late Devonian-Early Mississippian timing (360-370 Ma) for ore formation in southeast Missouri. Late Devonian-Early Mississippian fluids associated with the earliest stages of collisional tectonics and metamorphism to the south and southeast may have been important in the formation of southeast Missouri ore deposits. These tectonically driven waters may themselves have been the Mississippi Valley-type ore fluids, entering Missouri by way of the Black Warrior basin and Reelfoot rift and/or the Arkoma basin. Alternatively, the movement of orogenic fluids hundreds of kilometers distant may have initiated and distally influenced the migration of more locally derived Mississippi Valley-type ore fluids. Broad regions of Missouri and adjacent areas experienced heating and crustal flexing in the Late Devonian, and consequently, preservation of elevated temperatures in Mississippi Valley-type fluids as they move great lateral distances may not be necessary for ore formation in southeast Missouri.
- OSTI ID:
- 5667672
- Journal Information:
- Journal of Geology; (USA), Journal Name: Journal of Geology; (USA) Vol. 99:3; ISSN JGEOA; ISSN 0022-1376
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
AGE ESTIMATION
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
BRINES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CARBONIFEROUS PERIOD
DEVELOPED COUNTRIES
DEVONIAN PERIOD
DOLOMITE
ENVIRONMENTAL TRANSPORT
FEDERAL REGION VII
FLUIDS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
HEATING
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
LEAD ORES
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MASS TRANSFER
METAMORPHISM
MINERALIZATION
MINERALS
MINES
MISSOURI
NORTH AMERICA
ORES
ORIGIN
OXYGEN COMPOUNDS
PALEOZOIC ERA
RESERVOIR FLUIDS
RIFT ZONES
RUBIDIUM ISOTOPES
SEDIMENTARY BASINS
SILICATE MINERALS
STRONTIUM ISOTOPES
TECTONICS
UNDERGROUND FACILITIES
USA