Marta Oszczypko-Clowes

Stages of development in the Polish Carpathian Foredeep Basin

In southern Poland, Miocene deposits have been recognised both in the Outer Carpathians and the Carpathian Foredeep (PCF). In the Outer Carpathians, the Early Miocene deposits represent the youngest part of the flysch sequence, while in the Polish Carpathian Foredeep they are developed on the basement platform. The inner foredeep (beneath the Carpathians) is composed of Early to Middle Miocene deposits, while the outer foredeep is filled up with the Middle Miocene (Badenian and Sarmatian) strata, up to 3,000mthick. The Early Miocene strata are mainly terrestrial in origin, whereas the Badenian and Sarmatian strata are marine. The Carpathian Foredeep developed as a peripheral foreland basin related to the moving Carpathian front. The main episodes of intensive subsidence in the PCF correspond to the period of progressive emplacement of the Western Carpathians onto the foreland plate. The important driving force of tectonic subsidence was the emplacement of the nappe load related to subduction roll-back. During that time the loading effect of the thickening of the Carpathian accretionary wedge on the foreland plate increased and was followed by progressive acceleration of total subsidence. The mean rate of the Carpathian overthrusting, and north to north-east migration of the axes of depocentres reached 12 mm/yr at that time. During the Late Badenian-Sarmatian, the rate of advance of the Carpathian accretionary wedge was lower than that of pinch-out migration and, as a result, the basin widened. The Miocene convergence of the Carpathian wedge resulted in the migration of depocentres and onlap of successively younger deposits onto the foreland plate.

Stages in the Magura Basin: a case study of the Polish sector (Western Carpathians)

The Magura Basin domain developed in its initial stage as a Jurassic-Early Cretaceous rifted passive margin that faced the eastern parts of the oceanic Alpine Tethys. In the pre- and syn-orogenic evolution of the Magura Basin the following prominent periods can be distinguished: Middle Jurassic-Early Cretaceous syn-rift opening of basins (1) followed by Early Cretaceous post-rift thermal subsidence (2), latest Cretaceous–Paleocene syn-collisional inversion (3), Late Paleocene to Middle Eocene flexural subsidence (4) and Late Eocene - Early Miocene synorogenic closing of the basin (5). The driving forces of tectonic subsidence of the basin were syn-rift and thermal post-rift processes, as well as tectonic loads related to the emplacement of accretionary wedge. This process was initiated at the end of the Paleocene at the Pieniny Klippen Belt (PKB)/Magura Basin boundary and was completed during Late Oligocene in the northern part of the Magura Basin. During Early Miocene the Magura Basin was finally folded, thrusted and uplifted as the Magura Nappe.

Paleoecology of the Upper Eocene-Lower Oligocene Malcov Basin based on the calcareous nannofossils: a case study of the Leluchów section (Krynica Zone, Magura Nappe, Polish Outer Carpathians)

Paleoecology of the Upper Eocene-Lower Oligocene Malcov Basin based on the calcareous nannofossils: a case study of the Leluchów section (Krynica Zone, Magura Nappe, Polish Outer Carpathians) During the period of ca. 20 Ma (Middle Eocene-Chattian) the Leluchów Succession of the Magura Basin passed through drastic changes of sedimentary condition and paleobathymetry from well oxygened red shales with Reticulofragmium amplectens, deposited beneath CCD, red Globigerina oozes, to oxygen depleted organic-rich menilite-type shales and finally to flysch deposition of open marine conditions. The biostratigraphic and lithostratigraphic scheme is well established with the Leluchów Marl Member — Zones NP19-20 to NP22 (Late Eocene-Early Oligocene), Smereczek Shale Member, Zone NP23 (Early Oligocene) and the Malcov Formation s.s., Zone NP24 (Early-Late Oligocene). The aim of the paper is to present the quantitative analyses as the basis for paleoecological changes in the Magura Basin during the Late Eocene-Late Oligocene period. The changes manifest themselves through a decrease in the water temperature and progressing eutrophication. Species typical of brackish water conditions and restricted to the Paratethys region were identified from the NP23 Zone.

Sarmatian paleoecological environment of the Machów Formation based on the quantitative nannofossil analysis — a case study from the Sokołów area (Polish Carpathian Foredeep)

Sarmatian paleoecological environment of the Machów Formation based on the quantitative nannofossil analysis — a case study from the Sokołów area (Polish Carpathian Foredeep) The Machów Formation belongs to a supra-evaporitic succession of the Polish Carpathian Foredeep Basin (PCFB). Our studies were concentrated in the eastern part of the PCFB, north of Rzeszów. 33 samples were collected from five boreholes, at depth intervals as follows: Stobierna 2 — 1016-1338 m; Stobierna 3 — 715-1669 m; Stobierna 4 — 1016-1238 m; Stadnicka Brzóza 1 — 350-356 m and 1043-1667 m; Pogwizdów 2 — 1161-1390 m. The obtained biostratigraphical data gave evidence for the upper part of the NN6 (the Early Sarmatian) and for the NN7 (the lowermost part of the Late Sarmatian) Zones. All the nannofossil assemblages from Stobierna 2, Stobierna 4 and Pogwizdów 2 were assigned to the NN6 Zone. In the Stobierna 3 borehole the interval 1669-1113 m was assigned to NN6, whereas assemblages from depth interval 843-715 m belong to NN7 Zone. In Stadnicka Brzóza 1 interval 1667-1043 m belongs to NN6 Zone and interval 350-356 m to NN7 Zone. The Discoaster exilis Zone (NN6) was defined by the presence of Reticulofenestra pseudoumbilica, Sphenolithus abies, Helicosphaera walbersdorfensis and absence of Discoaster kugleri. The Discoaster kugleri Zone (NN7) assignment was based on the abundance of Coccolithus miopelagicus (> 10 μm), used as an alternative species essentially confined to that interval, and absence of Catinaster coalithus. The observed nannoplankton assemblages are predominantly composed of a high number of redeposited material, abundant long-ranging taxa and taxa resistant to carbonate dissolution. General assemblage compositions, obtained from quantitative data, indicate shallow near-shore environment and could confirm basin isolation.

Source areas of the Grybów sub-basin: micropaleontological, mineralogical and geochemical provenance analysis (Outer Western Carpathians, Poland)

Abstract The Grybów Unit occurring in the Ropa tectonic window was the subject of micropaleontological and geochemical investigation. Studies, based on calcareous nannofossils, proved that the level of reworked microfossil is not higher than 22 % and it varies between two sections. Quantitative analyses of the reworked assemblages confirmed the domination of Cretaceous and Middle Eocene species. The Sub-Grybów Beds, Grybów Marl Formation and Krosno Beds were assigned to the Late Oligocene and represent the terminal flysch facies. Detrital material accumulated in the Oligocene sediments originated from the Marmarosh Massif, which is the eastern prolongation of the Fore-Magura Ridge. The microscopically obtained petrological features agree with the chemical composition of the samples. Mica flakes, rounded grains of glauconite, heavy mineral assemblage, including abraded grains of zircon, rutile and tourmaline as well as charred pieces of plant tissues are reworked components. Enrichment in zircon and rutile is confirmed geochemically by positive correlation between Zr and SiO2. Zr addition is illustrated on 10×Al2O3–Zr–200×TiO2 and Zr/Sc vs. Th/Sc diagrams. Interpretation of the A–CN–K diagram and variety of CIA and CPA values indicate that the source rocks were intensely weathered granite-type rocks.

Reworked nannofossils from the Lower Miocene deposits in the Magura Nappe (Outer Western Carpathians, Poland)

Abstract Studies, based on calcareous nannofossils, proved that the level of reworked microfossils had so far been underestimated. More recently detailed quantitative studies of calcareous nannoplankton of the Magura, Malcov, Zawada and Kremna formations from the Magura Nappe in Poland documented a degree of nannofossil recycling among those formations. In the Late Eocene-Early Oligocene pelagic Leluchów Marl Member of the Malcov Formation the level of redeposition is very low (0-3.80 %), however, in the flysch deposits of the Malcov Formation reworking increased to 31.4 %. Late Oligocene through Early Miocene “molasse” type deposits of the Zawada and Kremna formations contain 43.7-69.0 % of reworked nannofossils. Quantitative analyses of the reworked assemblages confirmed the domination of Paleogene nannofossil species over Cretaceous ones. The most abundant, reworked assemblages belong to the Early- Middle Eocene age.