RECOGNIZING AND CHARACTERIZING KEY STRATIGRAPHIC SURFACES AND HORIZONS THAT DELINEATE GENETIC UNITS WITHIN THE IOLA LIMESTONE USING TEMPORAL AND SPATIAL TRENDS IN CONODONT DISTRIBUTION PATTERNS AND TAPHONOMY: UPPER PENNSYLVANIAN OF KANSAS

Sequence stratigraphic studies of the Iola Limestone in Kansas and adjacent states reveal more complexity than previously illustrated using the cyclothem model. The Iola Limestone and its members have long been considered a "classic" Kansas Cyclothem, representing one gradual transgression and regression. This model was supported by the stacking patterns of major lithofacies and temporal trends in conodont abundance and diversity. Stratal patterns revealed by the lateral tracing of key stratigraphic surfaces and horizons suggest that the Iola contains at least two major T-R units or High Frequency Sequences. Temporal trends in conodont distribution patterns appear to support this interpretation.

Conodonts were recovered from closely spaced vertical samples from several sections of the Iola in eastern Kansas, and temporal trends in diversity, abundance (elements/kg), relative abundance, and taxonomic composition were examined. Generic diversity of conodonts appears to be controlled by the type of stratigraphic surface, with abrupt drops in diversity appearing in samples directly above sequence boundaries, but with abrupt increases in diversity occurring in samples directly overlying both major and minor flooding surfaces. Concentrations of conodont elements occur in samples directly above all key stratigraphic surfaces. Sequence boundaries are the primary influence on stratigraphic ranges of conodont genera in the Iola. Several distinct fossil assemblages are illustrated by these boundaries.

Conodonts were recovered from samples directly above flooding surfaces and unconformities in the Iola and examined along a north-south transect to illustrate spatial trends in distribution patterns and taphonomy. Conodont distribution patterns suggest a correlation between sample composition and the relative location of the stratigraphic surface within the basin (updip versus downdip). Basinal trends of key stratigraphic surfaces within marine Paleozoic sequences can be characterized using trends in the distribution and taphonomy of conodonts.