Diagenetic alteration of the Wingate Formation: Possible indications of hydrocarbon microseepage, Lisbon Valley, Utah
- Io Geological Consultants, Fairfax, VA (USA)
- TYDAC Technologies, Arlington, VA (USA)
At most localities in southeastern Utah the Wingate Formation is a sandstone that exhibits generally uniform mineralogy and appearance. Along the southwest-dipping flank of the Lisbon Valley Anticline, however, substantial differences occur in the spatial distribution of authigenic kaolinite and hematite that permit differentiation of three outcrop areas. The northern and southern portions of this flank of the anticline are white (bleached). The bulk of the remaining, centrally located, Wingate outcrops are uniformly red (unbleached) because of hematite/clay coatings on constituent grains. Bleached rocks lack these grain coatings. In addition, most of the quartz grains in the bleached rocks have overgrowths. Compared to the other areas, the northern bleached rocks have three to five times more authigenic kaolinite, half the porosity, twice as many altered feldspars, and one-third as much mixed-layer clay. Both northern and southern bleached rocks contain hematite pseudomorphs after pyrite, and the northern rocks also contain hematite after siderite. Stratigraphy, primary depositional features, and petrography all demonstrate that post-depositional alteration resulted in the observed differences. Bleaching was driven by acidic and reducing fluids that infiltrated the strata, precipitating kaolinite and, locally, pyrite and siderite. Fluids either remained in the southern area for a shorter period of time or were less active and voluminous, resulting in less alteration than in the north. Late-stage oxidizing conditions locally converted siderite and pyrite to hematite. A probable source of the acidic/reducing fluids is leakage from the geographically associated sour petroleum reservoir at Lisbon Valley oil field.
- OSTI ID:
- 6935955
- Journal Information:
- Journal of Geology; (USA), Journal Name: Journal of Geology; (USA) Vol. 97:6; ISSN JGEOA; ISSN 0022-1376
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
ANTICLINES
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
CLAYS
COLOR
DEFORMATION
DEPOSITION
DIAGENESIS
FEDERAL REGION VIII
FELDSPARS
FLUIDS
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
HEMATITE
HYDROCARBONS
IRON CARBONATES
IRON COMPOUNDS
IRON ORES
IRON OXIDES
IRON SULFIDES
KAOLINITE
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OPTICAL PROPERTIES
ORES
ORGANIC COMPOUNDS
ORGANOLEPTIC PROPERTIES
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PETROGRAPHY
PETROLEUM DEPOSITS
PHYSICAL PROPERTIES
POROSITY
PYRITE
RESERVOIR FLUIDS
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEEPS
SIDERITE
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
STRATIGRAPHY
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
USA
UTAH