Subdivisions and correlations of the Tully Formation (Upper Devonian) in New York State and Pennsylvania on the basis of a statistical and stratigraphical analysis of selected conodonts.
A fourfold subdivision and a correlation of the calcareous parts of the Tully Formation in New York and Pennsylvania are based on the ratios of the abundance of the conodonts Polygnathus linguiformis, P. varca, P. iuvenis and Icriodus. The statistical distribution of the four taxa is independent of the local lithology, but follows stratigraphical units. The studied conodont faunal succession of the Tully Formation includes a conodont zone not yet described from Europe. This new zone is thought to be younger than the base of the Assise de Fromelennes (Upper Devonian, France) and is furthermore correlated with the lowest part of the to 1alpha zone (Upper Devonian, Germany). The conodonts of the Tully Formation are considered to be similar to those of the lower Geneseo Shale, the Alto Formation (Illinois), and the Cedar Valley Limestone (Minnesota).
Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4345.
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