Conodonts of the Kashirian Regional Substage (Moscovian, Middle Pennsylvanian) of the Volga Region near Rzhev (Tver Region, Russia)

Conodonts of the Kashirian Regional Substage in the Upper Volga region are studied for the first time. A conodont assemblage established in a quarry section near the village of Fedyaikino on the Osuga River, allows the correlation of the dolomite series with interbeds of marls and clays (11.45 m) with the Kashirian Nara Formation assigned to the Neognathodus bothrops Zone. In the section near the village of Mozgovo on the Derzha River, limestones and dolomites with cherts (7 m) are attributed to the upper part of the Kashirian, to the Neognathodus medadultimus Zone, although Member C, unconformably overlying Member B, may be Podolskian. Conodont assemblages are typical of sections of the East European Platform. The deposition took place in an offshore marine environment, while the basin coastline was located far to the west.