Roles of provenance, eustasy, and paleoclimates in determining diagenetic alterations in Pennsylvanian sandstones, Forest City basin mid-continent, U. S. A

Conference · Thu Feb 28 23:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5787115

Brenner, R L ^[1]; Scal, R ^[2]; Ludvigson, G A ^[3]

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1. Univ. of Iowa, Iowa City (United States)
2. Univ. of New Hampshire, Durham (United States)
3. Geological Survey Bureau, Iowa City, IA (United States)

Pennsylvanian quartz arenites and subarkoses in the Forest City basin have a variety of potential reservoir qualities that hinge on changes in siliciclastic provenance and diagenetic processes. Upward increases in the amounts of unstable grains and grain angularity record the unroofing of cratonic sedimentary rocks overlying crystalline basement rocks. Superimposed over this trend was a cyclic pattern of climatic changes controlled by eustatic sea-level and plate tectonic movements that profoundly affected early diagenetic processes. For example, plagioclase feldspars were altered as a result of the circulation of low pH, organic-rich waters through a moderately open hydrologic system. Coal deposits, paleoflora, and paleosols suggest that from Morrowan through middle Desmoinesian, sedimentation occurred under wet-humid to ever-wet tropical conditions conducive to unstable silicate mineral degradation. Upper Desmoinesian and Missourian climates were drier and thus more conducive to preservation of such minerals during transportation and to reduction in the amount of weathering after deposition. Upper Desmoinesian and Virgilian units were deposited during periods of increase marine influence within eustatically controlled cyclic sedimentary packages. These units were covered quickly by relatively impermeable marine shales and limestones, and reacted with modified marine fluids whose pH were buffered by carbonate equilibria. Drier climates in the Late Pennsylvanian resulted in reduced acidic meteoric pore water, leading to preservation of detrital apatite, reduced etching of garnet, and better preservation of feldspars. Feldspars in the Virgilian strata are much fresher, showing an increase in well-preserved grains and an overall reduction in the intensity of etch solution.

• OSTI ID: 5787115
• Report Number(s): CONF-910403--
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 75:3; ISSN AABUD; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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58 GEOSCIENCES
580000 -- Geosciences
CARBONIFEROUS PERIOD
DEVELOPED COUNTRIES
DIAGENESIS
DISSOLUTION
FEDERAL REGION VII
FELDSPARS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
IOWA
MINERAL RESOURCES
MINERALOGY
MINERALS
NORTH AMERICA
OXIDE MINERALS
PALEOCLIMATOLOGY
PALEONTOLOGY
PALEOZOIC ERA
PETROLEUM DEPOSITS
PH VALUE
PLATE TECTONICS
QUARTZ
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SILICATE MINERALS
TECTONICS
USA