THE LOCAL SOURCES OF DETRITAL MATERIAL IN MIDDLE DEVONIAN QUARTZITES OF THE DONETS BASIN: RESULTS OF U-Pb LA-ICP-MS ZIRCON DATING

Results of U-Pb dating of zircons from the Middle Devonian sandstones of the Mykolaivka Suite, taken from the junction zone between the Azov Domain of the Ukrainian Shield and Donets basin, are reported. The rocks are taken from a drill core and they occur beneath a 210 m sequence of mafic and ultramafic volcanic rocks that belong to the Antonivka (D2-3) and Mykolaivka (D2) suites. In total, 28 U-Pb isotope analyses were performed. The predominant population (18 grains) of zircons yielded a concordant age of 2075±9 Ma (MSWD = 0.64). The second largest population consists of zircon crystals with concordant to nearly concordant ages ranging from 3130 to 2830 Ma. These results indicate a local origin for the detrital zircons. The occurrence of coarse-grained terrigenous sediments, derived from local rock sources, indicates significant erosion of the Precambrian basement that might have been caused by differential vertical movements during the Middle Devonian period. In the Donets basin, rifting and uplift started ca. 10 Myr before that of other parts of the Prypyat-Dnieper-Donets Paleorift.