Pages: 299 - 309
Abstract: Lithostratigraphic, sedimentological and petrographic data collected from the lower portion (Eocene–Oligocene) of the ”Moldoviţa Lithofacies” (near the stratigraphic boundary with the underlying successions of the Tazlău ”Lithofacies”) show evidence of a turbidite system characterized by two different sedimentary supplies. Quartzarenite and litharenite sandstones, in fact, characterize the analysed stratigraphic succession, measured along the Ovăzu River, near the Ciumârna village (Bucovina region), thus testifying to the existence of two different provenances, linked to sediment sources tentatively identified with external cratonic areas and with inner crystalline belts together with their sedimentary cover, respectively. Moreover, the depositional trend, inferred by the facies analysis, shows an arenaceous interval interpreted as part of an active system (lobe or channel) included in thin and fine-grained facies probably belonging to fringe or marginal areas. Fine-grained lithofacies with menilite beds, typical of basin plain, are well represented in the upper part of the succession. Similar turbiditic deposits, but Oligocene–Miocene aged, are well known along the Betic-Maghrebian Chain (”Mixed Successions” auctorum), where they represent the stratigraphic interference of two opposite depositional systems closely linked to the starting of the tectogenesis preluding the closure of the Maghrebian Flysch Basin. Nevertheless, the analysed succession, very similar in composition and in textural characters to the Betic-Maghrebian ”Mixed Successions”, cannot assume the same significance. In this case, in fact, we suppose that the studied succession could be linked to a peculiar paleogeographical morphology of the sedimentary basin, excluding that tectonic events could have been the main control factors of the interaction of the two recognized different depositional systems, owing to the Eocene–Oligocene age of the lower portion of the ”Moldoviţa Lithofacies”, here analysed.
Keywords: Eocene-Oligocene, Eastern Carpathians, Romania, Moldovita Lithofacies, paleogeography, petrography, sedimentologyDownload PDF document