Petrology of lower and middle Eocene carbonate rocks, Floridan aquifer, central Florida

Conference · Sat Sep 01 00:00:00 EDT 1984 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6374329

Thayer, P A; Miller, J A

Study of cores from a US Geological Survey test well near Polk City, Florida, indicates that the Avon Park-Lake City (Claibornian) and Oldsmar (Sabinian) Limestones, which comprise most of the Floridan aquifer in central Florida, can be divided into six microfacies: foraminiferal mudstone, foraminiferal wackestone-packstone, foraminiferal grainstone, nodular anhydrite, laminated dolomicrite, and replacement dolomite. Dolomite containing variable amounts of nodular anhydrite forms more than 90% of the Avon Park-Lake city interval, whereas thte Oldsmar is chiefly limestone. Several episodes of dolomite formation are recognized. Laminated dolomicrite formed syngenetically in a supratidal-sabhka environment. Crystalline dolomite with nodular anhydrite formed early by replacement of limestone through reflux of dense, magnesium-rich brines. Replacement dolomite not associated with evaporites and containing limpid crystals probably formed later by a mixed-water process in the subsurface environment. Late diagenetic processes affecting crystalline dolomites include hydration of anhydrite to gypsum, partial dissolution of gypsum, minor alteration of gypsum to calcite, and dissolution of calcian dolomite cores in stoichiometric crystals. Crystalline dolomite and grainstone are the only rock types that have high enough porosities and permeabilities to provide significant yields of water. Medium and finely crystalline dolomites show best values of porosity and permeability because they have high percentages of intercrystal and moldic pores that are well connected. Filling of pores by anhydrite or gypsum can significantly reduce porosity and permeability.

• Research Organization: Amoco Production Co., New Orleans, LA
• OSTI ID: 6374329
• Report Number(s): CONF-8410143-
• Journal Information: Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 68:9; Conference: 34. annual meeting of the Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM, Shreveport, LA, USA, 24 Oct 1984
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
58 GEOSCIENCES
AQUIFERS
CARBONATE ROCKS
DIAGENESIS
PETROLOGY
FLORIDA
GEOLOGIC HISTORY
GROUND WATER
TERTIARY PERIOD
CENOZOIC ERA
FEDERAL REGION IV
GEOLOGIC AGES
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HYDROGEN COMPOUNDS
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OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
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WATER
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