Provenance of Upper Oligocene to Lower Miocene Krosno Formation sandstones in the Skole Nappe (southeast Poland): New insights from heavy minerals

Heavy minerals have been studied in order to address the problem of provenance and source area for the uppermost Oligocene to Early Miocene Krosno Formation in the Skole Nappe (Poland). The heavy mineral composition of the Krosno Formation in the Skole Nappe points to a metamorphic origin, mainly from pelites affected by amphibolite facies conditions. The Krosno Formation was deposited at least partly as a result of the uplift of the Sanok Island, whose petrography and geological affiliation remain enigmatic. This island was probably built of metamorphic and/or sedimentary rocks belonging to a pre-Alpine-uplifted ridge and its cover, exhumed in the transpression belt of the Weglowka Ridge, an interbasinal ridge located between the Skole and Silesian basins. Chemical composition of provenance sensitive minerals from the Krosno Formation suggests that their parent rocks could be genetically related to the Variscan system of ridges in the Carpathian region.