CRITERIA FOR RECOGNIZING THE BOUNDARIES OF STRATIGRAPHIC DIVISIONS OF THE SOUTHERN MEOTIC REGION OF UKRAINE FOR OSTRACODS

Abstract

Problem Statement and Purpose. Generalized results obtained in the implementation of the state topic IV‑1–18: «justification of the boundaries of regional and local stratigraphic divisions of the Phanerozoic of Ukraine for geological maps of the new generation» are. Criteria for recognizing the boundaries of stratigraphic divisions of the meшotic regioyarus of southern Ukraine by ostracods are established. Ostracod complexes were used to characterize the boundaries of stratigraphic divisions of the meotic region of southern Ukraine: ─ according to the leading species of ostracod (upper meotis ─ lower Pont); ─ by paleoecological characteristics of ostracod species (upper Sarmatian-lower meotis; lower-upper meotis). Data&Methods. Thus, complexes of meiotic ostracods were studied on the Kerch Peninsula: Yanysh-Takyl Mulda (Zavetne village), in the Crimea (Alminskа depression: Well. No. 302 (northern outskirts of Rivnopollye village), in the Black Sea depression: (Berezneguvate village (Mykolaiv region). When stratifying various deposits of the meotic regioyarus, it is very important to know the maximum possibility of practical use of ostracod complexes. Stratigraphic resolution of deposits of the meotic regioyarus of southern Ukraine by ostracod complexes-regiopidyarus, i.e. ostracods allow us to distinguish the lower meotic and upper meotic regiopidyarus. Thus, meotic ostracods allow us to distinguish two ostracod complexes in the lower meotic region-complex No. 1 (lower) and complex No. 2 (middle), and in the upper meotic region-complex No. 3. Results. The border between the upper Sarmatian and lower Meotic regions (complex No. 1 (lower)) is distinguished by paleoecological characteristics of ostracod species: Lower meotic region-complex (complex No. 1 (lower)): as noted earlier (Kovalenko, 2001), study of the species composition of lower meotic ostracods of complex No. 1 (Kerch Peninsula. The southern wing of the Yanysh-Takyl Mulda (Zavetne village)) gave grounds to assert that at that time there was a basin in the studied area that was very close in its bionomic conditions to the Kherson (upper Sarmat) one. The late Sarmatian ostracod fauna inherited by this early meotic Basin did not undergo significant changes, and the late Sarmatian ostracods Loxoconcha rimopora Suzin continued to exist; Euxinocythere suljakensis Suzin; Xestoleberis (Xestoleberis) maeotica Suzin; X. (X.) advena Schneider; X. (X.) goretski Golovko; X. (X.) irregularis Schneider and others. However, the appearance of meotic ostracodes, such as Loxoconcha obsoleta Ljuljev and Euxinocythere retituberculata Suzin, allows us to date these deposits to early meotis. The boundary between the lower meotic (complex No. 2) and upper meotic (complex No. 3) regions is distinguished by the paleoecological characteristics of ostracod species. For the first time for the Kerch Peninsula, the appearance of brackish ostracods of the Pontic type (Second migration wave) (Caspiocypris candida (Livental); Tyrrhenocythere pontica (Livental in Agalarova et al.), juv; Euxinocythere (Maeotocythere) praebacuana (Livental); Loxocorniculina diaffarovi Schneider, Loxoconcha praemitridata Agalarova, Camptocypria acronasuta (Livental). The boundary between the upper meotic (complex No. 3) and lower Pontic (complex No. 1) regions is recognized by the leading ostracod species (appearance of the Pontic type of ostracod fauna-genera Loxocorniculina Krstic, 1972; Camptocypria Zalanyi, 1959; Bacunella Schneider, 1958; Pontoniella Mandelstam, 1956; Caspiocypris Mandelstam, 1956 and others.