Paleogeography of the Holy Cross Mountains area in the Mesozoic

Author of the elaboration: prof. dr hab. Bronisław Matyja

When describing the history of the Holy Cross Mountains area in the Mesozoic we have to forget about the palaeogeography at the end of the Variscan folding, and, moreover, ignore the present-day hilly landscape. One of the features of the Holy Cross Mountains that is worth bearing in mind is that the present-day map of the Palaeozoic inlier is largely a perfectly preserved post-Variscan morphology of the area from approximately 250 million years ago. In this case, the preserving factor was the Mesozoic cover. The following paragraphs will explain how and why this happened and what are the lines of evidence for this situation.

In the Permian and Mesozoic the area of Poland was covered by a basin that was the eastern part of the Central European Basin (Kutek and Głazek 1972). Its NW-SE-oriented axial part is known as the Danish-Polish Trough. The north-eastern boundary of the trough corresponds to the south-western boundary of the East-European Craton, and the trough is subdivided by transverse tectonic zones into several segments differing in geological history (Dadlez 1997). One of these tectonic zones, the Tomaszów Mazowiecki-Grójec zone, is the north-western boundary of the Małopolska (Holy Cross) segment of the Danish-Polish Trough, corresponding to the area with the present-day Palaeozoic inlier of the Holy Cross Mountains and the Mesozoic margin. The margin is built of rocks representing all systems of the Mesozoic: the Triassic, Jurassic and Cretaceous. Besides the margin of the East European Craton and the Tomaszów Mazowiecki-Grójec tectonic zone, a significant role in the palaeogeography of the area was played by the Holy Cross Fault and its prolongation to the WNW (at least to the junction with the Tomaszów Mazowiecki-Grójec zone in the vicinity of Przedbórz) and the Meta-Carpathian Swell. The latter structure is a rather dynamically and ambiguously localized structural element (e.g. Marcinowski and Radwański 1983) with a parallel orientation, which several times had separated the Mid-Polish basin from the Tethyan basins. In the geological literature it has been referred to by various names, but currently corresponds to the Mid-Polish Uplands.The structural elements presented above will often be referred to in the description of the Mesozoic history of the Holy Cross Mountains.