Sequences within the Mississippian strata of the Central Appalachian Basin

Donald R. CHESNUT*
University of Kentucky, 228 MMRB, Lexington, KY 40506, USA; chesnut@uky.edu

Charles MASON
Morehead State University, Physical Sciences, 123 Lappin A, Morehead, KY 40351, USA

David M. WORK
Maine State Museum, 83 State House Station, Augusta, ME 04333, USA

Tournaisian siliciclastics of the Borden sequence (herein includes Sunbury, Maury, Borden, Cuyahoga, 
Pocono, Price and Grainger formations) prograded westward from old Acadian highlands in the east. 
It prograded across the Central Appalachian Basin toward the margin of the basin in Kentucky. The 
northwest striking Borden Delta Front in Kentucky marks the final delta ramp. To the east of the front, 
the Borden/Pocono wedge forms a delta platform. To the west of the delta front, thin basinal deposits 
of the Sunbury (starved basin) and New Providence/Maury (very distal prodelta) are all that represent 
the Tournaisian deposition in this region. The organic-rich black shales of the Sunbury represent the 
maximum flooding surface overlying the Famenian clastic wedge (Berea/Bedford). The Borden delta 
front represents the arrested development of the Borden/Pocono clastic wedge at the end of third-
order highstand through lowstand progradation. Discrete packages of siltstone, sandstone, red beds, 
and limey mounds probably represent the affects of fourth-order cycles, but a basin-scale, systematic 
litho- and biostratigraphic survey is lacking to differentiate and date many of the cycles. The "fossil" 
Borden delta front, delta basin and delta platform affected subsequent deposition through mid-
Mississippian times.
 
The mixed siliciclastic-carbonate strata of the Early Viséan Fort Payne sequence (herein the Fort 
Payne, Muldraugh, Renfro, Harrodsburg, Warsaw and Salem formations) filled in the remnant 
"Borden" basin with generally southwest prograding strata with discrete beds of shales, siltstones, 
sandstones, dolostones, and calcareous fenestrate- and crinoidal-biostromes. The thin glauconitic 
Floyds Knob bed at the base of the sequence traces the underlying Borden delta from basin to delta 
top and probably represents the maximum flooding surface of the third-order sequence. Up 
depositional dip, carbonates of the Renfro/Salem/Warsaw/Harrodsburg formations capped the 
siliciclastic basin fill at later stages. Some fourth-order cycles have been noted in the sequence, but 
no thorough, basin-scale study has been conducted to correlate these cycles with others around the 
world.

Late Viséan carbonates of the Slade sequence (herein includes Slade, Newman and Greenbriar 
formations) were deposited on the now extensive platform formed by the earlier Borden through Fort 
Payne cycles. However, this time, the Slade carbonates formed a platform to the west of a Late 
Viséan northeast-striking basin located in Virginia and eastern West Virginia. Fourth-order cycles 
within the Slade and its lateral equivalents have been noted, but further systematic studies are needed.
The Serpukhovian is represented by the Pennington sequence (herein includes the Pennington Group 
and Paragon Formation). This third-order sequence is dominated by siliciclastics that thicken along 
the northeast-striking axis of the Appalachian Basin. Sediment supply kept the basin largely filled as 
it subsided. The Pennington has numerous paleosols, red and green beds, coastal sandstones, marine 
shales and carbonates, and thin coals. This heterogeneous unit is certainly influenced by fourth-order 
eustatic cycles. However, detailed reconstructions are lacking and platform and ramp positions are 
unknown.

The Serpukhovian strata are unconformably overlain by Pennsylvanian coal-bearing siliciclastics. 
Along the margins of the basin the unconformity is probably a series of amalgamated unconformities 
of mid-Carboniferous age.

Despite the abundant world-class exposures of Carboniferous strata in the Central Appalachian Basin, 
the details of biostratigraphy are lacking to correlate all the fourth-order cycles with those of other 
areas around the world. With extensive exposures of fossiliferous rocks, this area may actually be the 
best place to examine Mississippian fourth-order cycles in detail. Ongoing biostratigraphic work is being conducted to elucidate these cycles.