Abstract

The Arkoma basin was depositionally part of a broad, stable shelf along a passive continental margin during much of its history. During the Chesterian, Morrowan, and early Atokan, the depositional patterns on the shelf varied greatly, depending on the inconsistent development of carbonate environments and the intermittent introduction of terrigenous elastics (quartz arenites) from the north.

Beginning with the middle Atokan, flexural downwarping of the south margin of the shelf was accompanied by down-to-the-south syndepositional normal faults developed sequentially to the north, as a result of continued collapse of the Ouachita trough. Lithic arenites were introduced into this developing trough from the east, apparently derived from a tectonic provenance southeast of the Ouachita trough, on the southwest margin of the Black Warrior basin. Further closure plus rapid deposition resulted in the closing and filling of this incipient foreland basin by the end of deposition of the middle Atoka.

With further compressional deformation, the axis of deposition shifted farther northward with the development of a fully formed and continually subsiding foreland basin (beginning in late Atokan). Lithic arenites were transported westward along the axis of the basin (documented in earliest Desmoinesian). In Arkansas some of the early Desmoinesian sediments apparently came from the uplifted Ouachita thrust belt immediately to the south.

During the rest of the early Desmoinesian (most of Krebs Group), with the continued subsidence of the foreland basin, extensive deltaic deposits (sublitharenites) were introduced from the north and provided the primary source of sediments to the foreland basin in Oklahoma. They apparently came from the continental interior to the west and north of the Ozark dome.

Although there is evidence of a limited source of sediments from the Ouachita fold belt in Arkansas during the deposition of the Hartshorne Sandstone (earliest Desmoinesian), the fold belt to the west in Oklahoma was apparently quiescent and presumably standing at or near sea level throughout the time of deposition of the upper Atoka and the whole of the early Desmoinesian Krebs Group (Hartshorne, McAlester, Savanna, and Boggy Formations).

Although added field confirmations are needed, it is concluded that renewed folding and uplift of the Ouachita fold belt following the deposition of the early Desmoinesian Krebs Group involved also the compression and folding of the Arkoma basin. This ended the progressive downwarping of this basin and shifted the depocenter still farther to the northwest. The core area of the Ouachita fold belt was extensively elevated for the first time resulting in the erosion and transportation of chert pebbles and other sediments to the northwest (Thurman Sandstone).

Beginning with the middle Desmoinesian, Cabaniss Group deposition was in a narrow successor foreland basin located to the north-west of the Arkoma basin and to the northeast of the Hunton arch. The Ouachita fold belt was the primary source for terrigenous sediments, periodically including chert-pebble conglomerates, to this area throughout the remainder of the Pennsylvanian.

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