Patterns of dolomitization in the Permian Park City Formation, northeastern Utah and western Wyoming

Journal Article · Tue Oct 01 00:00:00 EDT 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5815134

Whalen, M T ^[1]

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1. Syracuse Univ., NY (United States)

The Park City Formation was deposited on the Permian continental shelf and slope of western North America. This unit is a mixed carbonate, siliciclastic, evaporite sequence that in intercalated with phosphatic shales and cherts of the Phosphoria Formation. Four types of dolomite have been documented, by standard optical and cathodoluminescent (CL) petrography, x-ray diffraction, and scanning electron microscopy, in carbonate and heterogeneous facies of the Park City Formation. Two of these dolomite types consist of finely crystalline (<30 {mu}m) dolomite that exhibits bright-orange luminescence under CL. One type is found in shallow subtidal facies that commonly contain, or are overlain by facies that contain, anhydrite or calcite-replaced anhydrite nodules. Dolomitization often is pervasive but sometimes is patchy with some calcite microspar and lime mud present Dolomitization was probably the result of early diagenetic replacement of lime mud in sabka and peritidal settings. The second type of finely crystalline dolomite occurs in laminated organic-rich shales and dolomudstones. A third type of dolomite is medium to coarsely crystalline (30-100 {mu}m) and anhedral, exhibits a xenotopic fabric, and is dull red to dull orange under CL. Dolomitization usually is pervasive, occurs in several depositional facies, and replaces both carbonate matrix and allochems. This represents replacement of former carbonate and is related to a secondary stage of diagenesis. The fourth type of dolomite is coarsely crystalline (100-500 {mu}m), euhedral, has an idiotopic fabric, and occurs only rarely in rocks that had previously been silicified. These differing dolomite fabrics and textures imply that early diagenesis related to original, restricted depositional environments was responsible for producing the two finely crystalline types of dolomite.

• OSTI ID: 5815134
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:10; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EVAPORITES
DIAGENESIS
GEOLOGIC FORMATIONS
MINERALIZATION
LIMESTONE
PHOSPHATE ROCKS
UTAH
WYOMING
DOLOMITE
MINERALOGY
PERMIAN PERIOD
PETROGRAPHY
SCANNING ELECTRON MICROSCOPY
X-RAY DIFFRACTION
CARBONATE MINERALS
CARBONATE ROCKS
COHERENT SCATTERING
DEVELOPED COUNTRIES
DIFFRACTION
ELECTRON MICROSCOPY
FEDERAL REGION VIII
GEOLOGIC AGES
MICROSCOPY
MINERALS
NORTH AMERICA
PALEOZOIC ERA
ROCKS
SCATTERING
SEDIMENTARY ROCKS
USA
580000* - Geosciences