Carboniferous buildups in the Donets Basin (Ukraine)
Kyiv Taras Shevchenko National University, 90, Vasylkivska str., Kyiv, Ukraine, 03022; ogar_victor@ukr.net
Abstract
The Carboniferous (Mississippian and Pennsylvanian) of the Donets Basin contains bioherms and biostromes in several stratigraphic levels. The study of buildups of this region and their comparison with other areas allows to suggest that the composition of reef-building organisms changed during the Carboniferous. Up to the late Viséan, they were formed on a shallow water carbonate platform, whereas younger bioconstructions are restricted to distinctive limestone horizons of cyclothems. Viséan shallow-marine bioconstructions are represented by Siphonodendron-biostromes which are typical for the Late Viséan of many areas of the Paleothetys. In the unstable conditions of the paralic basin with frequent environmental changes bioconstructions formed during transgressive phases. The late Serpukhovian buildups were complex coral-chaetetid biostromes and bioherms. In Bashkirian times appeared chaetetid and coral-chaetetid biostromes as well as algal bioherms. During the early Moscovian coral and coral-chaetetid biostromes were the most common. During the middle Moscovian dominated bioherms probably of microbial origin, and at the end of Moscovian time chaetetid biostromes were typical. During the earliest Gzhelian time algae-sponge bioherms appeared in the Donets Basin.