SCYPHOZOAN COMMUNITIES AND FACIES DEPENDENCY IN THE FORT PAYNE FORMATION (LOWER MISSISSIPPIAN) OF CENTRAL TENNESSEE

The Fort Payne Formation is a marine shallowing-upward sequence with distinct facies representing different environments that were present during the Lower Mississippian Period in central Tennessee (Cheatham and Davidson Counties). Like the Elgin Member of the Maquoketa Formation (Upper Ordovician) in northeastern Iowa, the Fort Payne Formation has preserved a well-developed and segregated scyphozoan community that has strong dependency to these distinct facies. The first scyphozoan is a previously undescribed Paraconularia species, and the second is a simple, small, and solitary Spenothallus species, and they are almost exclusively found in the shale facies. The shale facies represent the deepest basinal setting for the Fort Payne and is interpreted as having been deposited just above maximum storm-weather wave base. The shale facies grades into a siltstone facies as the Fort Payne Formation continued to shallow. The siltstone facies contain the most diverse scyphozoan community in the Fort Payne. The most abundant was a large Sphenothallus, and the lesser common scyphozoans are Conularia subcarbonaria, Paraconularia missouriensis, and the previously mentioned undescribed Paraconularia sp. This siltstone facies represents a slope environment preceding an encroaching carbonate platform. At the top of the Fort Payne Formation the siltstone facies become increasingly punctuated by sheet-like packstone layers until the Fort Payne grades into the Warsaw Limestone. It is in relation to these sheet-like packstones that the final scyphozoan shares a strong connection as Paraconularia missouriensis can most commonly be found on the surfaces of these sheet-like packstones. There are additional finds indicating that Paraconularia missouriensis inhabitated the Warsaw carbonate platform possibly showing a preference to coarser carbonate sediments.