Regional bryozoan biostratigraphy and taphonomy of the Edenian stratotype (Kope Formation, Cincinnati area); graphic correlation and gradient analysis

A regionally correlated biostratigraphic gradient divides the Kope Fm. (Late Ordovician, Indiana-Kentucky-Ohio) into twelve bryozoan concurrent range zones averaging 7.6 m in thickness. Stratigraphic (temporal) resolution has been enhanced by post-mortem lateral dispersal of bryozoans by storm processes. Abundance patterns reflect a bathymetric gradient in the original benthic communities. The presence and absence of short-ranging genera define a temporal gradient of faunal replacement within these communities. Both gradient analysis and graphic correlation indicate significant regional correlations between sections, and a robust biostratigraphic zonation. Gradient analysis also indicates regionally consistent variation in sedimentation rates and key horizons (isochrons) probably generated by taphonomic processes.