Dolomitization of the Madison Group, Wyoming and Utah overthrust belt
Two stages of pretectonic dolomitization are recorded in the upper Madison Group of the Wyoming-Utah thrust belt. Marine to hypersaline dolomitization occurred during deposition of upper Madison carbonates and evaporites in peritidal and sabkha settings. This timing is supported by the common association of fine-grained, nonluminescent dolomite with restricted, shallow-water facies, and the relatively enriched isotopic composition of the dolomite (delta/sup 18/O = +2.0 per thousand; delta/sup 13/C = +4.0 per thousand). A second stage of dolomitization began during exposure of the Madison shelf and continued through deposition of the overlying Amsden Formation. Regressions and transgressions during this time caused migration of marine-meteoric mixing zones across the Madison shelf and widespread dolomitization of all depositional facies within the Madison Group. The second stage of dolomitization is volumetrically dominant, has a meteoric isotopic composition (delta/sup 18/O = -2.0 per thousand; delta/sup 13/C = +2.0 to +7.0 per thousand), and in most locations has masked the isotopic record of the first-stage, synsedimentary dolomite. In addition to replacive dolomite, dolomite and calcite cements were also formed during this diagenetic stage. These three components exhibit isotopic variations concomitant with stratigraphic position that reflect spatial gradients in ground water chemistry. 16 figures, 1 table.
- Research Organization:
- Univ. of Michigan, Ann Arbor
- OSTI ID:
- 5753357
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 71:8; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
DIAGENESIS
DOLOMITE
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
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NORTH AMERICA
OXYGEN COMPOUNDS
PETROLEUM DEPOSITS
RESERVOIR ROCK
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USA
UTAH
WESTERN US OVERTHRUST BELT
WYOMING