Exotic Triassic pelagic limestone pebbles from the Pieniny Klippen Belt of Poland: a further evidence for early Mesozoic rifting in West Carpathians

Abstract

Egzotyki pelagicznych wapieni triasowych z górnej kredy pienińskiego pasa skałkowego Polski: świadectwo wczesnomezozoicznego otwarcia basenu oceanicznego w Karpatach Zachodnich Exotic Triassic limestone pebbles from Upper Cretaceous conglomerates yielded microfaunal (mainly conodont and holothurian) evidence for pelagic conditions of sedimentation in the Pieniny Klippen Belt Basin, Carpathians, Poland, during the Carnian and Norian stages, the topmost Norian (topmost Sevatian) Misikella hernsteini — Parvigondolella andrusovi Assemblage Zone inclusively. These Triassic rocks are developed in grey spotty limestone facies, lithologically very similar to the Fleckenkalk - Fleckenmergel facies of Lower-Middle Jurassic in Tethyan realm. This may suggest persistence of open-sea carbonate sedimentation conditions in the axial part of the Klippen Belt Basin right through the Triassic (Rhaetian) — Liassic (Hettangian) boundary. Together with earlier published data from the Pieniny Klippen Belt of Slovakia, our results support the view that opening of the Klippen Belt Basin by oceanic-type rifting occurred prior to Late Triassic, probably already during the Anisian. The pelagic exotic Middle- Upper Triassic limestones, nowhere present at the surface in the Pieniny Klippen Belt, had probably been derived by erosional destruction of an accretion prism built of Triassic and Jurassic basinal deposits obducted as a result of Late Creataceous subduction of oceanic-type crust of the Klippen Belt Basin under the Exotic Andrusov Cordillera.