Burlington Conodonts and Tournaisian-Visean Boundary, Hannibal, Missouri, and Burlington, Iowa: ABSTRACT

Abstract

At its type-locality in Iowa, the Burlington Limestone consists of thick-bedded white limestones of the Dolbee Creek and Cedar Fork Members separated by the brown, iron-rich, and dolomitic carbonates of the Haight Creek Member. At Hannibal, Missouri, however, the Burlington has five divisions. An unnamed unit underlies the Dolbee Creek Member and another overlies the Cedar Fork; both unnamed units resemble the Haight Creek Member. Dolbee Creek sections at both locations are nearly the same age. The Cedar Fork, however, is younger at Hannibal than at Burlington. Bactrognathus distortus occurs in the uppermost Dolbee Creek and lower Haight Creek at Hannibal and is restricted to the lower Haight Creek near Burlington. Eotaphrus occurs through most of the Cedar Fork and within the uppermost Haight Creek near Burlington, but ranges from the middle Haight Creek into basal Cedar Fork at Hannibal. In Iowa, Taphrognathus is not present in the Burlington Limestone, but first appears at the base of the overlying Keokuk Limestone. At Hannibal, Taphrognathus occurs through most of the uppermost unnamed unit of the Burlington. At Hannibal, the Tournaisian-Visean boundary occurs in the upper part of the Burlington Limestone. Near Burlington, it coincides with the Burlington-Keokuk contact.