Conodont biostratigraphy of the Middle to Upper Devonian boundary beds in the Kielce area of the Holy Cross Mts

Abstract

Principal stages in development of the conodont faunas of the passage facies area between the Kielce stromatoporoid-coral platform and Łysogóry intrashelf basin (sensu lato) in the vicinity of Kielce, the Holy Cross Mts, Central Poland, were apparently controlled by facies changeovers stemming from stepwise drowning of the Kielce shoal area. Abrupt transitions from an impoverished polygnathid to polygnathid-ancyrodellid (frequently enriched in Polygnathus? dengleri) to that of diverse pelagic polygnathid-mesotaxid (or icriodontid) biofacies, were a response to pulsatory eustatic rises. A sequence of early Ancyrodella species, crucial for recognition of the Middle/Upper Devonian boundary, is established at Wietrznia and Czarnów sections; in particular, a phyletic succession in the Wietrznia-I profile permits subdivision of the Mesotaxis falsiovalis Zone into at least 3 Ancyrodella levels of global correlation potential. Need of quantitative study of the early ancyrodellid variability, and revision of the series boundary-point in the global stratotype are emphasized, as well as complex ecologic provenances of ancyrodellids.