Large-volume gravity flow deposits in the Central Carpathian Paleogene Basin (Orava region, Slovakia): evidence for hyperpycnal river discharge in deep-sea fans

Abstract

Abstract:The deep-water clastic systems of the Central Carpathian Paleogene Basin contain megabeds, which are developed in distinctive stratigraphic horizons and can be traced over long distances. These beds are characterized by great individual thickness (4-13 m), uniform lithology and internal structures. On the basis of their lithology, sedimentary structures and sequence development, the megabeds are characterized by 15 individual facies and interpreted from the viewpoint of flow hydrodynamics. The grain-size distribution and internal structures of the megabeds point to their deposition from uniform turbulent flows. The main controlling factor for generation of such large voluminous flows is inferred in the sea-level changes, when a relative rising of sea level during the Eocene/Oligocene boundary was responsible for long-lasting accumulation of the clastic supply at the basin margins. The large volume of detritus from river discharge and ravinement surfaces of flooded land was accumulated on the shore and in the conduit heads where the sediment was remobilized by other triggers. The flows generated by catastrophic floods during the early Rupelian sea-level lowstand are thought to be the most probably triggering mechanism. The large highly erosive hyperpycnal flows from flooding rivers could erode accumulated deposits in the conduit or on steeper basin-margin slopes and could cause progressive increase of the sand volume in the flow. Conduit flushing appears to be the most probable source of sediment for the very large voluminous flows that were responsible for deposition of the Orava megabeds.

Turbidite sedimentology, biostratigraphy and paleoecology: A case study from the Oligocene Zuberec Fm. (Liptov Basin, Central Western Carpathians)

“…Location of studied sections (Liptovská Ondrašová outcrop: 49°05'52.56" N,19°34'22.98" E;Ráztoky outcrop: 49°06'06.02" N,19°33'56.51" E). Starek et al 2004) with the occurrences of sandstone megabed events (Golab 1959;Sliva 2005;Starek et al 2013). The Zuberec Formation and the Biely Potok Formation compose the up-section, predominantly consisting of rhythmically bedded turbidites and massive sandstones and represent the various sand-rich submarine fan facies associations (e.g., Westwalewicz-Mogilska 1986;Wieczorek 1989;Soták 1998;Starek et al 2000;Sliva 2005;Starek & Fuksi 2017a, b).…”

Oligocene turbidite fans of the Dukla Basin: New age data from the calcareous nannofossils and paleoenvironmental conditions (Cergowa beds, Polish–Slovakian borderland)

“…Facies in the proximal sections of the succession, located in the western part of the Dukla Tectonic Unit at Iwla, Lipowica and Tylawa (Fig. 1), suggest sediment supply to the deep marine Cergowa beds depositional system by high-density turbidites and hyperpycnal flows as megaturbidite beds of the Central Carpathian Paleogene Basin (Starek et al 2013) fed from a directly connected delta (Plink-Björklund & Steel 2004). Such a paleogeographic relationship is suggested by complexes of beds with sedimentary features implying deposition by aggrading sustained turbidity currents (Kneller & Branney 1995) and containing exceptionally high proportions of coalified plant detritus, including tree trunks present at Lipowica (Plink-Björklund & Steel 2004).…”

Distal turbidite fan/lobe succession of the Late Oligocene Zuberec Fm. – architecture and hierarchy (Central Western Carpathians, Orava–Podhale basin)

“…This formation is overlain by the Huty Formation (the Zakopane beds) which mainly includes various mud-rich deep marine deposits [e.g. 3,45,46] with occurence of sandstone megabed events [47]. The lowermost part of the Huty Formation includes Šam-bron Beds sensu Chmelik [48] (Szaflary beds in the Podhale basin) which occure in the northen part of the Podhale-Spiš Magura area and embraced shaly and thinto medium-rhythmic turbidite deposits with intraformational conglomerates and breccias.…”