A TALE OF TWO CYCLOTHEMS: A COMPARISON OF TWO SECTIONS OF THE IOLA HIGH FREQUENCY SEQUENCE USING SEQUENCE STRATIGRAPHY AND CONODONT DISTRIBUTION PATTERNS (UPPER PENNSYLVANIAN; IOWA AND KANSAS)

High-frequency sequences of the Iola Limestone in Iowa and Kansas can be distinguished and correlated using the temporal and spatial distribution of conodonts in conjunction with a sequence stratigraphic analysis. The taphonomic and taxonomic differences of conodonts will help distinguish between depositional environments and the stories lithofacies tell. At least two unconformity-bounded HFS's can be delineated in the Iola Limestone in sections in Iowa and Kansas. This interval was previously interpreted as representing a single cyclothem.

The repetition of specific lithofacies in addition to the temporal distribution patterns of conodonts has been used to interpret the Iola Limestone as a single cyclothem. The upward progression of lithofacies from thin transgressive limestone to carbonaceous shale and finally to thick regressive limestone suggests that the Iola represents a single transgressive-regressive unit. A comparison of two sections of the Iola Limestone from Winterset, Iowa and Kansas City, Kansas done using sequence stratigraphic analysis of significant surfaces coupled with an investigation of the temporal and spatial distribution patterns of conodonts using closely spaced samples may contradict this interpretation. The vertical stacking patterns of lithofacies in these sections appears to be very similar, however, the dark shale facies (core shale) in the Iowa section contains many calcareous intervals with a benthic fossil assemblage. The character of this facies and stratal patterns of correlative surfaces suggests that this part of the Iola may be the transgressive part of a cycle.