Thermal Maturity of the Grajcarek Unit (Pieniny Klippen Belt): Insights for the Burial History of a Major Tectonic Boundary of the Western Carpathians

Abstract

The Grajcarek Unit of the Pieniny Klippen Belt (PKB), at the boundary between the Central (Inner) and Outer Carpathians, resulted from the convergence of the ALCAPA (the Alps–Carpathians–Pannonia) block and European plate. The strongly deformed slices of the Grajcarek Unit consist of Jurassic–Cretaceous sedimentary rocks associated with Late Cretaceous–Middle Palaeocene synorogenic wild-flysch, and sedimentary breccias with olistoliths. Maximum burial temperatures and burial depths were estimated based on vitrinite reflectance data. The vitrinite reflectance values were wide scattered through the Grajcarek sedimentary succession, especially in the flysch formations. This is attributed mainly to the depositional effects that affected the vitrinite evolution. The determined maximum burial temperatures were interpreted due to the regional compression controlled by tectonic burial coeval with thrusting and strike-slip faulting. The regional vitrinite reflectance variations might estimate cumulative displacement around the NNW–SSE and oriented the strike-slip Dunajec fault, which is a continuation of the deep fracture Kraków–Myszków fault zone.

Lineaments in the Gravity Image of the Border Zone between the Central and Outer Carpathians

“…The Miocene andesitic dykes and sills are located near the PKB-Magura Nappe border (Figure 2). Intrusions cut through the Magura Nappe and the PKB form andesitic dykes and sills distributed along the Pieniny Andesitic Line (PAL) [22,26,27]. The sediments that form the Outer Carpathian nappes were originally deposited in the Mesozoic and Cenozoic basins belonging to the western part of the Tethyan realm [23,24].…”