The Aquitanian marine deposits in the basement of Polish Western Carpathians and its palaeogeographical and palaeotectonic implications

Abstract

Early Miocene mudstones and conglomerates were discovered in the Andrychów 6 borehole, beneath the Polish Western Carpathians. These dark grey mudstones contain calcareous nannoplankton belonging to the Aquitanian NN1 zone, which can be correlated with the Egerian Stage of the Central Paratethys. The marine mudstones are underlain by conglomerates and sandy-silty deposits of Oligocene age, which overlapped the Early Palaeozoic-Precambrian platform basement. The conglomerates display features of fan delta deposits, and were supplied with material derived from erosion of the uplifted part of platform basement (Cieszyn-Slavkov Ridge). The Egerian mudstones from the Andrychów 6 borehole, and the Eggenburgian Zebrzydowice Formation known from the Karvina and Cieszyn area, reflect a progressive flooding of the European Platform during the Egerian/Eggenburgian transgression. The Egerian-Oligocene mudstones and conglomerates,as well as the Zabrzydowice Formation are equivalents of the youngest flysch deposits in the Outer Carpathians. The Egerian deposits from the Andrychów area and the Eggenburgian Zebrzydowice Formation from the Cieszyn and Ostrava areas are relicts of a broad marine embayment which flooded southern Poland and linked the terminal flysch basin and the adjacent European shelf.The sub-thrust Aquitanian (Egerian) to Langhian (Early Badenian) deposits in the Andrychów-Zawoja-Cieszyn area recorded a sedimentary-tectonic evolution of the southern edge of the European Platform. This time span covers the Egerian-Eggenburgian/Ottnangian marine deposition, the Late Ottnangian overthrust of the Outer Carpathians, the Karpatian alluvial fan deposition, uplift of the Cieszyn-Slavkov Ridge, the Late Karpatian-Early Badenian marine transgression and the subsequent Late Badenian to Sarmatian telescopic thrusting of the Outer Carpathians.