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

Two Ar-40/Ar-39 spectrum measurements on well-preserved volcanic feldspar ( sanidine) from the coal tonstein horizon 1(3)(1) from the lower Kashirsky g roup (middle Moscovian stage) of the Donets Basin Upper Carboniferous (Ukra ine) 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 Carbonif erous. Taking the correlation of the 1(3)(1) horizon and the recently publi shed 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 po ints to inaccurate or even erroneous correlation, and we therefore are comp elled to suggest a reconsideration of the validity of the current biostrati graphic correlation between the Carboniferous of western and East Europe.