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Early Strawn Biostratigraphy: What Is the Caddo?

A. M. Reid

"Caddo limestone" is used to describe parts of the lower Strawn limestone on the Eastern shelf. The lower Strawn limestone was generally deposited on an eroded Ellenburger surface, but may overlie eroded Mississippian or even Atokan rocks preserved in topographic lows on the Ellenburger surface. Above the Caddo limestone is a sequence of clastics overlain by the Goen Limestone of early Strawn age. The Goen Limestone, in turn, is overlain by clastics which are overlain by the late Strawn Capps Limestone. As long as knowledge of fusulinid zonation was restricted to rocks of early Cherokee, late Cherokee, and Marmaton age, regional correlations of these carbonate units were manageable. With refinement of zonation, however, the Caddo, Goen, and Capps limestones can be subdivi ed into discrete units of different age. In each of these age zones, the units are further divisible on the basis of environments of deposition and subsequent diagenesis. Current results indicate that the early Strawn carbonates are cyclical and were deposited during numerous glacio-eustatic sea level fluctuations.

AAPG Search and Discovery Article #91037©1987 AAPG Southwest Section, Dallas, Texas, March 22-24, 1987.