Abstract

Distinctive differences between Late Desmoinesian to Early Missourian cyclic deposits on opposite shores of the Pennsylvanian Arkoma Sea were noted during outcrop mapping in eastern Oklahoma.

The north shore deposits conform to the classical midcontinent Pennsylvanian cyclothem. A regressive blanket sandstone is succeeded in turn by underclay, coal and carbonaceous shale, transgressive calcareous shale and/or limestone, black fissile shale with phosphate nodules, and, finally, gray shale with calcareous to sideritic inclusions that, upward, becomes increasingly silty to sandy.

The south shore deposits that border the Ouachita and Arbuckle uplifts in southeastern Oklahoma reveal a more symmetrical cycle than for the preceding. Both transgressive and regressive sandstones are present, and, although exceedingly lenticular, tend to converge northward to enclose a fluviatile tongue of red beds and conglomeratic lenses. The adjacent transgressive marine wedge contains fossiliferous gray to black shales. Limestones are thin and developed near tops and bottoms of shale sequences.

Open sea deposits are much more variable. High sea level phase is characterized by subtidal gray shale with subordinate bioturbated siltstone to sandstone. Sole marks are locally prominent. A low sea level phase often consists of inter tonguing north and south shore deposits.

Effects of eustatic oscillations of sea level were imprinted on a steadily subsiding depositional trough. Many stratigraphic horizons that reflect sea level reversals are useful for regional correlations. Application of this concept to the polycyclic Holdenville Formatin of Hughes County indicates its northward continuation as the Memorial Shale and the overlying previously miscorrelated Seminole Formation of Tulsa County and also its subsurface projection into the oil productive Cleveland Sandstones. These correlations are supported by fossils determinations.