High-precision 40Ar/39Ar spectrum dating on sanidine from the Donets Basin, Ukraine: evidence for correlation problems in the Upper Carboniferous

Two 40 Ar/ 39 Ar spectrum measurements on well-preserved volcanic feldspar (sanidine) from the coal tonstein horizon 1 3 1 from the lower Kashirsky group (middle Moscovian stage) of the Donets Basin Upper Carboniferous (Ukraine) yielded well-defined plateaus with an average age of 305.5 ± 1.5 Ma. The age is to be interpreted as sedimentation age of the coal tonstein and thus defines a chronostratigraphic time mark in the East European Carboniferous. Taking the correlation of the 1 3 1 horizon and the recently published time scales for the Upper Carboniferous as a basis for comparison, the age of 305.5 Ma is about 6 Ma too young. This age discrepancy obviously points to inaccurate or even erroneous correlation, and we therefore are compelled to suggest a reconsideration of the validity of the current biostratigraphic correlation between the Carboniferous of western and East Europe.