PALEOTOPOGRAPHIC CONTROL ON THE LOCATION OF TRANSGRESSIVE SYSTEMS TRACT PARASEQUENCES: MISSISSIPPIAN (CHESTERIAN) HARTSELLE FORMATION, NORTH-CENTRAL TENNESSEE

A detailed study of eleven exposures of the Hartselle Formation, the contact with the underlying Monteagle Limestone, and the uppermost Monteagle was conducted over an approximately 150 Km² area in northcentral Tennessee. To document paleo-relief on the sequence boundary at the Hartselle/Monteagle contact—a major regional disconformity—sections were correlated using a locally traceable flooding surface within the uppermost Monteagle that places shelfal packstones on top of inter to supratidal shale and dolomicrites. A N/S trending scarp approximately 7 m high and no more than 2 Km wide divides the disconformable surface into a lower western and a higher eastern portion. The fluvial facies of the basal Hartselle parasequence directly overlies the Monteagle and can be shown to abut this scarp. This basal parasequence is restricted to the western portion of the study area. The second-oldest parasequence is not geographically restricted and blankets the entire study area. This is not the classic incised valley fill because the paleoshoreline as defined by the transition to deltaic facies occurs within 5 Km to the south, however, the disconformity developed on subaerially exposed Monteagle Limestone continues nearly 350 Km further south to the associated lowstand deposits in northern Alabama. Deltaic and shoreface parasequences within the Hartselle in the study area clearly show a transgressive stacking pattern, placing this unit within a transgressive systems tract.