The tectonic evolution of the Plzeň Basin(Upper Carboniferous, West Bohemia): a review and reinterpretation

Abstract

Three periods can be recognized in the Upper Paleozoic tectonic history ofthe Plzeň Basin corresponding to Westphalian C, Westphalian D to Stephanian B, and Stephanian C to Autunian times, respectively. During the Westphalian C period, the main tectonic compression was oriented approximately N-S. Dextral strike-slip faulting on NW-SE faults and associated normal faulting on N-S conjugate faults resulted in the development of the Central Graben of the Plzen Basin which is interpreted as a pull-apart basin. Dextral strike-slip activity can also be demonstrated for other NW-SE faults outside the Plzeil Basin (especially for the Elbe Lineament) which control the Upper Carboniferous limnic sedimentation in the Bohemian Massif. During the Westphalian D - Stephanian B period, the tectonic compression was oriented NNW-SSE. The activity of NW-SE strike-slip faults and N-S conjugate normal faults decreases while normal faulting on NW-SE conjugate faults becomes dominant. Between Stephanian B and Stephanian C further minor anticlockwise rotation of the principal compression into the NW-SE direction occurred. As a result, sinistral strike-slip faulting on NNE-SSW fractures became dominant accompanied by normal faulting on NW-SE conjugate faults. This situation persisted until the Lower Permian. Sinistral wrench movements invoked the initiation of a NNE-SSW transtensional asymmetric graben in the Plzen and Zihle basins, and the foundation of similar structures (Blanice and Boskovice furrows) in other parts of the Bohemian Massif. Main tectonic lines were reactivated during the Saxonian tectonics in the Tertiary.