Correlation of Mid-Continent Virgilian (Late Pennsylvanian) Brachiopods
C. Pius Weibel
Biostratigraphic correlations of Pennsylvanian strata in the Illinois basin with those of the Western Interior basin have been restricted largely to comparison of ostracode faunules and a few fusulinid occurrences. Seventeen brachiopod species from the Bogota and Greenup Limestone Members of the upper Mattoon Formation in east-central Illinois resemble species from Late Pennsylvanian Mid-Continent localities. Five Bogota species have relatively restricted ranges and are useful for correlation. Neochonetes granulifer var. transversalis is rare in the Douglas Group but abundant in the Shawnee and Wabaunsee. Lissochonetes geinitzianus var. plattsmouthensis ranges from uppermost Missourian to upper Shawnee and L. geinitzianus var. geronticus ranges from upper Wabaunsee to Low r Permian. Derbyia texana occurs in the Thrifty Formation of north Texas (probably upper Shawnee or lower Wabaunsee). Antiquatonia jemezensis has not been reported in the Mid-Continent but occurs in the upper Madera Formation (probable Shawnee or early Wabaunsee) of New Mexico. A compositid from the younger Greenup Limestone Member is morphologically intermediate between the Early Pennsylvanian Composita wasatchensis and the middle Permian C. affinis. Other species from the Bogota and Greenup Members range throughout the Upper Pennsylvanian, except for one linoproductid of Missourian affinities.
This study, along with a previous study of brachiopods (Shumway Limestone Member) and of fusulinids, indicates that the Bogota is of middle Shawnee age, the Greenup is of upper Shawnee or lower Wabaunsee age, and the Missourian-Virgilian boundary in the Illinois basin is stratigraphically near the Omega Limestone Member.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.