EVALUATION OF THE DESMOINESIAN-MISSOURIAN STAGE BOUNDARY IN EASTERN KANSAS VIA BENTHIC FORAMINIFERA

The primary objective of this research is to improve upon the foraminifera zonal scheme within the Midcontinent of North America from a stratigraphic interval that historically yielded no documented occurrence of these fauna in Kansas (i.e., the majority of the Pleasanton Group). The Pleasanton Group encompasses the regional North American conodont-based Desmoinesian-Missourian Stage Boundary, and we present here initial findings from ongoing research for samples collected from the Lenapah Limestone through Shale Hill formations.

Fifty-two samples were collected from four drill cores. Drill cores include the Deffenbaugh Quarry 1-B, Edmonds ‘A’1, FUQUA, and PNR #1, located in Johnson, Leavenworth, Elk, and Linn counties, respectively, in eastern Kansas. We initially identify occurrences of several benthic foraminifera species within the Glenpool and Exline Limestone members. Deffenbaugh Quarry 1-B exhibited the highest abundance and diversity of benthic foraminifera, including Ammodiscus semiconstrictus, Bullopora redoakensis, Triticites cullomensis, Textularia virgilensis, and Tolypammina nodosa. In contrast, Edmonds ‘A’1 yielded three species: Ammodiscus semiconstrictus, Endothyra macra, and Textularia virgilensis. The FUQUA drill core primarily yielded Ammodiscus semiconstrictus and Textularia fragments, while Stacheia pupoides, Nodosaroum gaptankensis, and Textularia virgilensis were recovered from PNR #1.

Further work remains before this unzoned interval can be further defined; however, at present, these findings are consistent with a Kasimovian age when comparing to global data. Future work will include further sampling of additional units within the Pleasanton and underlying Marmaton groups to improve upon the presently documented occurrences of benthic foraminifera, comparison to other faunal occurrences, such as conodonts, and evaluation of the regional and global series and stage boundary, as defined by benthic foraminifera.