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> report > MGS-Winston-v3 1994
Miami Geological Society Publications The Paleogene of Florida, Volume 3, Lithostratigraphy of the Cedar Keys Formation of Paleocene and Upper Cretaceous Age - Peninsular Florida and EnvironsBy George O. Winston ABSTRACT The Cedar Keys occurs throughout the Florida Peninsula and environs within the confines of the Rebecca Shoal barrier reef. The Cedar Keys is subdivided by lithologic character and corresponding geophysical log characteristics into six units. In descending order they are: Unit A, characterized by a preponderance of anhedral and cryptocrystalline dolomite; euhedral dolomite is subordinate. Unit B is characterized by the presence of numerous relic grain textures in chalky to microcrystalline euhedral dolomite. Unit C is predominately anhydrite, with subordinate chalky to very fine microcrystalline euhedral dolomite. Unit D is characterized by a predominance of relic grains in a chalky to very fine microcrystalline euhedral dolomite, with few thin bedded anhydrites. Units E & F are similar in texture to Unit D, but contain fewer beds of relic grain texture. They are differentiated from each other only by E-log correlation. The presence of Borelis gunteri establishes that at least Unit B and upper Unit C are Paleocene in age. Regional correlation shows that Units E and F are equivalent to, and a facies of, the Upper Cretaceous Pine Key Formation. The Cedar Keys carbonate fraction is all dolomite; it and probably the associated anhydrites are secondary replacement of limestone. The secondary nature of the dolomite is demonstrated by the presence of numerous beds containing relic grain texture throughout the formation. Subsidence of the South Florida Basin and Southeast Georgia Embayment continued throughout Cedar Keys deposition. The Peninsular Arch does not appear on the isopach of the A-D interval; this interval is not involved with facies changes into the Pine Key Formation. The Plantation Tongue
of the Rebecca Shoal barrier reef partially encircled the Peninsula in the
late Upper Cretaceous and was responsible for the deposition of Units E
and F. In the Paleocene, the Tavernier Tongue completely encircled the Peninsula
and was responsible for the dolomite-anhydrite deposition of Units A through
D. (The entire report is available below*) *Please note: Report pages containing Figures 17-21 were not available.
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