Stress field changes in Central Europe from late Miocene to Quaternary as determined from volcanic rocks in the Bohemian Massif

Abstrakt

This work presents the results of paleostress investigation in dated Mio-Pliocene volcanic rocks in the vicinity of Lądek Zdrój town in the Rychlebské hory Mts., as a part of central Sudetic Mts. in NE Bohemian Massif. Six different paleostress field regimes since Late Miocene to Quaternary were distinguished.

Each stress regime is characterized by orientation of principal parameters and is discussed in relation to the known paleostress regimes within the surrounding regions of the Sudetic Mts., Fore-Sudetic block, and European Alpine foreland in central Europe. The results show switching of tectonic phases with dominant compression, transtension or extension.

Moreover, the orientation of theoretical planes with maximal shear stress and with high tendency to dilate for individual paleostress regimes are defined and compared with orientation of known faults within the study area suggesting their possible kinematics. The timing of the derived regimes is determined more accurate and is in a good accordance with the data reported from different regions in central Europe, which suggests their broader validity.

In addition, one or shorter events interrupting the main Plio-Quaternary extensional regime and one differently oriented Plio-Quaternary extension regime were newly discovered and constrained based on several dated phases of volcanism of the faulted rocks.