WHITESIDE, JOSEPH R., Univ. of Texas at Dallas, Richardson, TX; and LAWRENCE K. HINDE, Baylor Univ., Waco, TX

ABSTRACT: Condonont Biochronology and its Implications on the Mid-Carboniferous Lithostratigraphy of the Frontal Ouachita Mountains, Oklahoma

Conodont biostratigraphic data from the Ouachita Mountains indicates Carboniferous lithostratigraphic units are apparently diachronous and time transgressive, although, formation boundaries have been considered both lithostratigraphic and chronostratigraphic. Six conodont assemblages are recognized from the fauna studied in the ouachitas: two Mississippian (Meramecian?-Chesterian) and four Pennsylvanian (Morrowan-Atokan). The distribution of these assemblages suggests modifications of previous biostratigraphic assignations of the lithostratigraphic units.

Some stratigraphic miscorrelations result from similar facies present in different formations: the Caney, "Springer," and Johns Valley Formations' black shale facies; the "Springer," and Johns Valley Formations' olistostromes; and the Jackfork and Atoka Formations' similar successions of turbidites and shales. Equating the Caney and "Springer" Formations to the chronostratigraphic subdivisions Mississippian and Pennsylvanian is unwarranted because conodont data indicate the Caney Formation is partly Pennsylvanian. Conodonts recovered from the Johns Valley Formation indicate a Pennsylvanian designation slightly older than workers previously estimated. Lithofacies transition across the frontal ouachitas is unmistakable in the late Morrowan Wapanucka and early Atokan "Spiro" Formations. radation of isochronus Wapanucka limestone to Chickachoc Chert develops southward to Pine Mountain Fault, where pinchout of the "Spiro" sand also occurs. South of this fault the Wapanucka and "Spiro" Formations are no longer recognized and application of the term "Spiro" south of Pine Mountain fault is unjustified. Considering the limited number of depositional settings developed at the mid-carboniferous basin-to-margin transition, lithostratigraphic and chronostratigraphic relationships become more important with increased exploration in the Arkoma basin and Quachita Mountains.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.