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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 481

Last Page: 481

Title: Diagenetic Phenomena of Chipola Formation, Calhoun County, Florida: ABSTRACT

Author(s): M. John Kocurko

Article Type: Meeting abstract


The Chipola Formation crops out along the Chipola River, Ten Mile Creek, and Farley Creek in Calhoun County, Florida. The formation, dated at 16.1 m.y.B.P., is predominantly an unconsolidated, bioclastic wackestone. These carbonate rocks have undergone very little diagenetic alteration, and as a result fossil preservation is excellent. Original mineralogy is essentially unchanged, and most shell material is aragonite or high-magnesian calcite. X-ray analysis of unlithified sediment indicates a composition of approximately 75% aragonite and 25% high-magnesian calcite. Disregarding the age of the formation, the unit is considered to be in a very early stage of lithification.

Cementation occurs locally in the unit by the formation of low-magnesian calcite as microspar. The lithified parts of the formation take on a nodular appearance as bioclastic debris is cemented. "Nodules" are usually less than 15 cm in diameter. Sparry calcite locally may be a void-filling cement, but this is usually confined to lithified burrows. Cementation within burrows is apparently controlled by the presence of organic mucus in the sediment. Early stages of pseudosparitization can also be observed in shell material. Alteration to pseudospar appears as a migrating or advancing "front" through the shell material.

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