Lower Badenian coarse-grained Gilbert deltas in the southern margin of the Western Carpathian Foredeep basin

Abstract

Two coarse-grained Gilbert-type deltas in the Lower Badenian deposits along the southern margin of the Western Carpathian Foredeep (peripheral foreland basin) were newly interpreted. Facies characterizing a range of depositional processes are assigned to four facies associations -topset, foreset, bottomset and offshore marine pelagic deposits. The evidence of Gilbert deltas within open marine deposits reflects the formation of a basin with relatively steep margins connected with a relative sea level fall, erosion and incision. Formation, progradation and aggradation of the thick coarse-grained Gilbert delta piles generally indicate a dramatic increase of sediment supply from the hinterland, followed by both relatively continuous sediment delivery and an increase in accommodation space. Deltaic deposition is terminated by relatively rapid and extended drowning and is explained as a transgressive event. The lower Gilbert delta was significantly larger, more areally extended and reveals a more complicated stratigraphic architecture than the upper one. Its basal surface represents a sequence boundary and occurs around the Karpatian/Badenian stratigraphic limit. Two coeval deltaic branches were recognized in the lower delta with partly different stratigraphic arrangements. This different stratigraphic architecture is mostly explained by variations in the sediment delivery and /or predisposed paleotopography and paleobathymetry of the basin floor. The upper delta was recognized only in a restricted area. Its basal surface represents a sequence boundary probably reflecting a higher order cycle of a relative sea level rise and fall within the Lower Badenian. Evidence of two laterally and stratigraphically separated coarse-grained Gilbert deltas indicates two regional/basin wide transgressive/regressive cycles, but not necessarily of the same order. Provenance analysis reveals similar sources of both deltas. Several partial source areas were identified (Mesozoic carbonates of the Northern Calcareous Alps and the Western Carpathians, crystalline rocks of the eastern margin of the Bohemian Massif, older sedimentary infill of the Carpathian Foredeep and/or the North Alpine Foreland Basin, sedimentary rocks of the Western Carpathian/Alpine Flysch Zone).

Quantitative characterization of the sedimentary architecture of Gilbert-type deltas

“…Differences in the size of deltas can be due to temporal and spatial variations in the magnitude of accommodation-space generation and in rates of sediment supply even within the same depositional settings, as documented in the examined dataset (Fig. 5), and reported in the case of simultaneously forming deltas (e.g., Martini et al, 2017;Nehyba, 2018;Winsemann et al 2018). For example, different coeval deltas occurring along the same basin-bounding fault can exhibit physiographic differences in relation to their position, as deltas located closer to the fault tips may receive a larger volume of sediment per unit time, while experiencing lower rates of subsidence, which collectively can promote their basinward progradation (Gupta et al, 1999;Young et al, 2000).…”

Coastal sandy spit deposits (Lower Burdigalian/Eggenburgian) in the Alpine-Carpathian Foredeep of Lower Austria

“…Prov enance study pro vides data about the source area, which might be es pe cially im por tant in case of the prograding clinoforms and eval u a tion of long shore drift typ i cal for coastal spits. Prov e -nance re sults fur ther sup port the palaeocurrrent pat terns, palaeo ge ogra phy or even the se quence strati graphic in ter preta tions (Dinis et al, 2016;Nehyba, 2018). Such a com par i son might at test the ori en ta tion of the prograding clinoform in re lation to the coast (i.e.…”

Vegetation and climate changes during the Miocene climatic optimum and Miocene climatic transition in the northwestern part of Central Paratethys

“…The NN5 biozone dated Iváň, Lomnice, Židlochovice, and Baden Soos localities represent unlaminated glauconitic calcareous clays—“tegel”—with intercalations of calcareous sands or sandstone and limestone. Oscillation of nutrients, temperature, salinity, oxidation intensity, water column stratification, as well as an increase of seasonality are inferred from the marine fossils and sedimentological characteristics (Brzobohatý et al, 2003; Cicha, Seneš, & Tejkal, 1967; Ćorić & Hohenegger, 2008; Doláková et al, 2014; Doláková, Brzobohatý, Hladilová, & Nehyba, 2008; Doláková, Kováčová, & Basistová, 2011; Holcová et al, 2015; Nehyba, 2018; Nehyba et al, 2008, 2016; Rögl et al, 2008).…”

“…In the northwestern part of the Paratethys, a system of sedimentary basins such as the Carpathian Foredeep, Vienna and Danube basins evolved since the Oligocene due to the extensional and compressional phases leading to the uplift of Carpathians orogenic chains (Kováč et al, 2017; Kováč et al, 2017; Kováč, Márton, Klučiar, & Vojtko, 2018; Meulenkamp, Kováč, & Cicha, 1996). The shallow to deep marine Miocene sediments of the western Central Paratethys represent classical strata of regional sequence and biostratigraphy (e.g., Harzhauser & Piller, 2007; Hohenegger, Ćorić, & Wagreich, 2014; Kováč et al, 2007; Kováč et al, 2018; Kováč et al, 2018; Kováč, Hudáčková, et al, 2017; Nehyba, 2018; Nehyba, Holcová, Gedl, & Doláková, 2016; Nehyba, Petrová Tomanová, & Zágoršek, 2008; Piller, Harzhauser, & Mandic, 2007) including various regional stratotype localities that have been intensely studied with respect to a variety of geological proxies and marine fauna (e.g., Brzobohatý, Cicha, Kováč, & Rögl, 2003; Papp, Cicha, Seneš, & Steininger, 1978; Planderová, 1990).…”