ABSTRACT: Stratigraphy and Biostratigraphy of the New Albany Shale (Devonian-Mississippian) in the Illinois Basin.
NORBY, RODNEY D., Illinois State Geological Survey, Champaign, IL, and FRANK R. ETTENSOHN, University of Kentucky, Lexington, KY
Conodont studies from 18 outcrop sections and one core greatly aid in correlating the five members (Blocher, Selmier, Morgan Trail, Camp Run, and Clegg Creek, in ascending order) of the New Albany Shale within the Illinois basin and to equivalent units within the Appalachian basin. The members form a succession of alternating black (Blocher, Morgan Trail, and Clegg Creek) and gray shales (Selmier and Camp Run).
The outcrop sections contain similar successions of conodont zones through the five members of the New Albany Shale. The Blocher, at its type section, contains the middle varcus subzone (middle Givetian) through at least the early falsiovalis zone (early Frasnian). The overlying Selmier contains the late hassi zone through the late rhenana zone (Frasnian). The Morgan Trail includes the linguiformis zone (latest Frasnian) in the lower part and probable zones through the late triangularis zone (early Famennian) in the upper Morgan Trail. A fauna indicative of the early through late crepida zones dominates the Camp Run, but the rhomboidea zone probably occurs in the upper portion. The Clegg Creek spans parts or all of the three marginifera zones through at least the late duplicata zone ( arly Kinderhookian). These ages indicate that members at the type New Albany are somewhat older than previously believed.
In Kentucky, closer to the Cincinnati arch, Frasnian and early Famennian conodont zones are generally present as a lag deposit on top of the Blocher. The middle and late Famennian interval also thins toward the arch.
AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)