Abstract
The submarine Iváň Canyon oriented parallel along the front of the Western Carpathian fold and thrust belt and the foreland of the Bohemian Massif has been studied on numerous 2D seismic sections and available borehole cores. The canyon can be followed over the distance of more than 75 km indented within the sedimentary infill of the Alpine-Carpathian Foredeep from Lower Austria into the Czech Republic.
Seismic data reveal up to 600 m depth of the canyon and its width of 2.5-6 km. The canyon is characterized by a low sinuosity planform architecture with an axial main channel and several tributary channels of varying dimensions.
Six seismic facies were identified, separated by three erosional surfaces, which led to recognition of seven evolutional stages of the canyon. Facies analysis, clast composition and heavy mineral spectra indicate derivation from a siliciclastic source area, cannibalization of an older basin infill and an important role of sustained low-density turbidity currents in transport and deposition.
The strontium isotope stratigraphy data supported by microbiostratigraphy and by foraminiferal δ(18)O and δ(13)C isotope analysis confirmed, that the depositional history of the canyon infill lasted from the upper Burdigalian/Langhian boundary up to the lower Serravalian, with the dominance of Langhian deposits in its infill. The formation and depositional history of the canyon is explained by the complicated structural and depositional history of the Alpine-Carpathian Foreland basin during the lower/middle Miocene transition and middle Miocene (Langhian) with a dominant role of tectonic subsidence and basin re-configuration accompanied by eustatic sea-level fluctuations.
The Iváň Canyon as axial channel developed in the elongate foreland basin reveals several differences if compared to typical ancient submarine canyons in the passive margin settings.