CONODONT BIOSTRATIGRAPHY OF THE WHITEHOUSE QUARRY, WHITEHOUSE, OHIO

Lacking a detailed biostratigraphic framework of Middle Devonian carbonates on the Wabash Platform and the surrounding margins of the Michigan, Appalachian, and Illinois basins, impedes our understanding of the stratigraphic history of this area. No studies have yet documented the conodont fauna present in the Whitehouse Quarry (roughly 30 km southwest of Toledo), along the northern margin of the Wabash Platform coincident with the southern margin of the Michigan Basin. The carbonates exposed in the Whitehouse Quarry are currently placed within the Dundee Formation, though previous work indirectly suggests a thin limestone bed (~25 cm) isolated at one locality at the top of the quarry is assignable to the lowermost Silica Shale.

Nineteen samples obtained from the top of the quarry down, 5.5 meters, to the water level contained a uniform, low-diversity Icriodus fauna that lacked zone-defining Polygnathus species. Previous studies on the Wabash Platform faced similar results. The conodont fauna does not conclusively support the assignment of the topmost bed to the Silica Shale, as species first occurring in the Givetian, present in nearby Givetian deposits, were not discovered. Comparing the conodonts of the Whitehouse Quarry with their total stratigraphic ranges reported in North America constrains deposition of the carbonates from the costatus through the ensensis zones. The zonal range could be further constrained to the australis and kockelianus zones, if the local ranges, which are slightly truncated on the Wabash Platform, are used. Though more tenuous, using the absence of species in the Whitehouse Quarry, which are found nearby on the platform, reduces the range from the late australis through the kockelianus zones. It appears the quarry exposes an upper portion of the Dundee Formation and correlates to the upper 4.5 m of the Dundee Formation in nearby Silica, Ohio, to the upper portion of the Dundee Formation in St. Marys, Ontario, to the top 9 m of the dolomites (excluding the bone bed) of the Bellefontaine Outlier, to the Delaware Formation along the on the eastern margin of the Wabash Platform (exposed in Central Ohio and in the Parkertown Quarry in Northern Ohio), and possibly in part to the Speed Member (North Vernon Limestone) in southern Indiana.