Deep structure of the Pieniny Klippen Belt in Poland

Abstract

An interpretation of the deep structure of the Pieniny Klippen Belt in Poland is presented, utilizing a high-resolution deep seismic reflection survey. The studied profiles reach a depth of around 23 km. The seismic lines depict the structure and mutual relationships between the main domains analyzed—the Central Carpathians (CC), the Pieniny Klippen Belt (PKB) and the Outer Carpathians. The seismic lines show the Central Carpathian Paleogene (CCP) sediments covering the Tatric units and overlying Krížna and Choč nappes of the CC south of the PKB. The entire nappe pile comprising the CC units is thrust over sedimentary rocks that probably derived from the European Plate, representing a mixture of autochthonous platform Paleozoic to Neogene sediments and slices of Outer Carpathian and PKB rocks. The older crystalline basement of the European Plate is suspected to be below these sedimentary rocks. The reflections below 20 km depth show a possible boundary between different crustal elements within this plate. The PKB is part a of 3–5 km wide flower structure, limited by fault zones that include faults cutting across sediments of the CCP and the Magura Nappe. The fault marking the southern limit of the PKB is particularly well visible in the seismic sections. The Albian–Lower Miocene flysch sequences, constituting the main components of the PKB, form north-vergent thrust-sheets. During the Albian to Miocene the PKB originated as an accretionary prism in front of the moving CC Plate, followed by plate rotation and strike-slip processes. The entire CC nappe pile is thrust over the Precambrian and Lower Paleozoic crystalline basement of the European Plate and probably slices of the PKP. The Outer Carpathians display an allochthonous character above the European Plate and comprise several north-verging imbricated nappes (thrust-sheets). The European plate dips gently southwards below the PKB and the CC Plate, cut by several deep-reaching faults.