The Azalea carbonate biogenic bank developed on a broad shallow shelf during early Strawn deposition.

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Petrologic study of cores and well cuttings defined 3 major facies. The "deeper water" micrite is dark brown with scattered fossil fragments and was deposited in water from 50 to 200 ft deep. The biogenic bank facies is composed of biosparite to biosparudite containing platy algae, fusulines, bryozoans, gastropods, pelecypods, brachiopods, and some crinoid columnals. The "sheltered" micrite contains numerous small unidentifiable foraminifers deposited behind the bank, and a few very local biogenic mounds. These mounds seem to be analogous with the mangrove islands found in Florida Bay.

Bank development was confined to the west edge of an Atokan structural terrace where oscillation waves were impinging upon the rising sea floor. Turbulence, shallow water, and the associated supply of nutrients provided necessary ingredients for prolific growth of organisms which formed the biogenic bank.

Excellent hydrocarbon production has been obtained from the bank across 13 mi of its length. Recently production was extended 1 3/4-mi south and an extension is being drilled 1½-mi north. There is a good possibility of additional biogenic banks having developed on the broad Strawn shelf.

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