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

Conference · Sat Sep 01 04:00:00 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-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 68:9
• Country of Publication: United States
• Language: English

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AQUIFERS
CARBONATE ROCKS
CENOZOIC ERA
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