Clues to Evolution of an Intracontinental, Transtensional Basin System: Clastic Sequence Geometries in the Bohemian Cretaceous Basin, Central Europe

Ulicny, David¹, Lenka Spicakova¹, Jiri Laurin¹, Radomir Grygar², Stanislav Cech³ (1) Czech Academy of Sciences, Prague, Czech Republic (2) VSB-Technical University, Ostrava-Poruba, Czech Republic (3) Czech Geological Survey, Prague, Czech Republic

Strike-slip deformation along basement shear zones trending roughly NW-SE (in present-day coordinates) has been a typical feature of Central European crust since the Late Paleozoic Variscan orogeny. The Elbe Fault System (EFS), prominent in the geological picture of Eastern Germany and the Czech Republic, is a good example of an intraplate fault system that underwent multiple reactivations between the Carboniferous and Late Cenozoic. During the Mid-Cretaceous, a significant reactivation of the Elbe Zone led to the formation of the Bohemian Cretaceous Basin. A study of basin-fill geometry, palaeogeography, and facies trends in a number of time-slices, based on detailed sequence stratigraphy, revealed an evolving interplay of individual structural elements within a broad fault zone that gave rise to a transtensional basin system. The distribution of shear within a broad area of faults sub-parallel to the principal displacement zones of the EFS contributed to the small displacement on individual faults and to relatively low rates of subsidence. In addition, the Bohemian Cretaceous Basin was characterized by a significant role of faults antithetic to the EFS and trending approximately NNE. These antithetic faults strongly influenced the intra-basinal topography during the initial phase of fluvial to estuarine deposition (Cenomanian), and later (Turonian/Coniacian), when the basin became a fault-bounded seaway, they defined the borders of principal depocenters. The Bohemian Cretaceous Basin differs in many features from plate-margin basins of large strike-slip displacement rates and high rates of subsidence and can be viewed as one of potential models for intra-plate transtensional settings.