Age of deep-seated fracture zones in Lower Silesia (Poland), based on K-Ar and palaeomagnetic dating of Tertiary basalts

Abstract

Wiek głębokich stref uskokowych na Dolnym Śląsku na podstawie datowania radiometrycznego I paleomagnetycznego bazaltów trzeciorzędowych K-Ar and palaeomagnetic dating of Tertiary basaltic rocks related to deep fracture zones in the area between the Fore-Sudetic Monocline and the Sudetic Block, Lower Silesia (Poland), allowed to distinguish three major phases of Tertiary tectonic deformation: (1) the Odra phase of tension (late Oligocene) which produced the Sudetic Boundary Fault (NW-SE) and .the Odra Fault zone (NW-SE on the west, changing to WNW-ESE on the east); (2) the Opoie phase of compression (late Oligocene/early Miocene), (Corresponding to the Savian phase of folding in the Carpathians, which produced strike-slip faults (SW-NE) transversal to the Odra Fault, and possibly also resulted in some compressional rotation along the Sudetic Boundary Fault plane; (3) the Jawor phase of tension (Middle Miocene, mainly Badenian), corresponding to the Styrian phase, which produced faults (WNW-ESE) in the Kaczawa Mountains (Sudetic Block).