Structural evolution of the Gnieździska Syncline - regional implications for the SW Mesozoic margin of the Holy Cross Mountains (Central Poland)

Basing on analysis of tectonic mesostructures, the structural evolution stages of the Gnieździska Syncline have been determined. The structure represents a typical example of folds occurring in the SW margin of the Holy Cross Mountains. The well-exposed syncline displays a wide variety of structures, including: shear and extension joints, stylolites, cleavage, strike-slip and dip-slip faults as well as master joints. Tectonic structures resulting from flexural slip indicate that the Gnieździska Syncline developed as a flexural-slip fold as a result of horizontal NE-SW compression. The subsequent deformation phase included mesostructures pointing to the increasing activity of a nearby Gnieździska-Wola Morawiecka dextral strike-slip fault of regional extent. In the terminal phase of the post-kinematic uplift of the Holy Cross Mountains, T joints and master joints appeared.