Provenance of the Upper Triassic–Lower Jurassic Flysch and the Middle–Upper Jurassic Coarse Clastic Sequences in the Cimmerides of the Crimean Mountains Based on the Results of U–Th–Pb Isotopic Dating of Detrital Zircon Grains

• Published in: Stratigraphy and geological correlation 2022-08, Vol.30 (4), p.228-249
• Main Authors: Kuznetsov, N. B., Romanyuk, T. V., Nikishin, A. M., Strashko, A. V., Kolesnikova, A. A., Dubensky, A. S., Sheshukov, V. S., Lyapunov, S. M., Novikova, A. S., Moskovsky, D. V.
• Format: Article
• Language: English
• Subjects: Accumulation; Archaeology; Basements; Continental margins; Cratons; Crystal structure; Crystallinity; Dating; Deep water; Deformation; Dinosaurs; Earth and Environmental Science; Earth Sciences; Flysch; Geophysics/Geodesy; Gondwana; Grains; Historical Geology; Isotopes; Jurassic; Lead; Massifs; Mountains; Oceans; Paleoceanography; Permian; Provenance; Sandstone; Sediment; Sedimentary basins; Sedimentology; Sediments; Segments; Shallow water; Strata; Stratigraphy; Structural Geology; Triassic; Uplift; Zircon
• ISSN: 0869-5938; 1555-6263
• DOI: 10.1134/S0869593822040050

New results of U–Th–Pb isotopic dating of detrital zircon grains from the sandstones of the Upper Tauric Formation of the Crimean Mountains, belonging to the Lower Jurassic part of the Tauric Group, are presented. Comparison of the obtained age sets of detrital zircon grains with similar data for the clastic rocks of both lower and higher stratigraphic levels of the Cimmerides of the Crimean Mountains shows a significant difference between them. This reflects radical changes in the sources of sediment supply for the studied strata, which took place at the Triassic–Jurassic boundary and at the beginning of the Middle Jurassic. During the Late Triassic–Jurassic time, the sedimentary basins of the Crimean Mountains were formed directly on the southern (in present-day coordinates) continental margin of the East European segment of Eurasia. During the Late Triassic, the vast Scythian–Tauric megabasin was located here. Mostly shallow-water sediments accumulated in its northern part, in the Scythian sedimentary basin, and flysch deposition took place in its southern part, in the Tauric deep-water sedimentary basin. The clastic components of the flysch are dominated by the products of destruction of the crystalline basement complexes of the Sarmatian segment of the East European craton (EEC), the equivalents of the crystalline complexes exposed at present within the Ukrainian Shield and the Voronezh crystalline massif. The clastic material was supplied to the Tauric basin in transit via the Scythian basin. At the Late Triassic and Early Jurassic boundary, detrital material from the EEC ceased flowing into the Tauric sedimentary basin. But detrital material, the primary sources of which were the crystalline complexes of Gondwana and the peri-oceanic complexes of the Rheic and Paleo-Tethys oceans, started to flow into it. This means that the paleogeographic situation on the southern margin of the East European segment of Eurasia changed dramatically during the Early Jurassic. The Scythian–Tauric megabasin as it existed during the Late Triassic disappeared. The Dobrogea–Crimea Uplift emerged in its northern part (Scythian sedimentary basin). However, no significant changes in the depositional environment took place in its southern part (Tauric sedimentary basin). Deep-water flysch accumulation continued there during the Early Jurassic. This inherited sedimentary basin is hereinafter referred to as Late Tauric to emphasize the difference of its sedimentary fill from t