Fault geometry and evidence of depocentre migration within a transtensional intra-basinal high : a case study from the Łączna Anticline (Intrasudetic Synclinorium, SW Poland)

The paper presents the results of geological mapping and a detailed structural analysis carried out in the Łączna Anticline. This elevated region coincides with the Zawory (Cz. Závora) mountain range in the Central Sudetes (SW Poland). The Łączna Anticline separates two minor geological units (depressions) within the northwestern part of the Intrasudetic Synclinorium – the Krzeszów and the Police brachysynclines. In numerous exposures of Triassic and Upper Cretaceous sedimentary rocks, several brittle and a few soft-sediment deformation structures have been recognized. Their orientation and spatial distribution suggest that the Łączna Anticline is a horst-like, intra-basinal high, formed due to permanent extension, dextral strike-slip movements within fault zones, and negative flower structures. The studies did not confirm the occurrence of continuous deformations such as anticlinal bends and flexures. The results show that the preservation of some lithological varieties of sedimentary rocks within modern morphological and structural elevations reflects the migration of centres of maximum subsidence within a pull-apart basin system. A new structural and geodynamic interpretation for the Łączna Anticline area is proposed.