A deep palaeovalley in the floor of Polish Carpathian Foredeep Basin near Pilzno and its control on Badenian (Middle Miocene) evaporite facies

Abstract

The Pogórska Wola palaeovalley of com bined tec tonic and ero sional or i gin dis sects the Me so zoic floor of the Carpathian Foredeep Ba sin to a depth ex ceed ing 1200 m. It formed dur ing Paleogene times pre sum ably due to flu vial and sub ma rine ero sion, con cen trated along a lo cal pre-Late Badenian graben sys tem. All mem bers of the foredeep's Badenian-Sarmatian sed i men tary fill at tain dis tinctly greater val ues in side the palaeovalley than on top of el e vated pla teaux on palaeovalley shoul ders. The fill com prises the Early to Late Badenian sub-evaporite Skawina For ma tion, the lat er ally equiv a lent Late Badenian evaporite Krzyżanowice and Wieliczka for ma tions and the su pra-evaporite Late Badenian to Early Sarmatian Machów For ma tion. Over the pla teaux and in the high est palaeovalley seg ment, the evaporites are de vel oped in the sulphate fa cies Krzyżanowice For ma tion, whereas in the lower palaeovalley seg ments chlo ride-sul phate fa cies evaporites of the Wieliczka For ma tion oc cur. The rock salt-bear ing rocks are in volved in thrust ing and fold ing at the Carpathian orogenic front, which helps to as sess the lat eral ex tent of the Wieliczka For ma tion in seis mic re cords. The deep palaeotopographic po si tion of the evaporites in side the palaeovalley, com bined with their lithological and sed i men tary fea tures, point to their forma tion via sub aque ous grav ity flow-driven redeposition of orig i nally shal low-wa ter evaporites, pref er en tially ha lite-bear ing, pre sum ably com bined with pre cip i ta tion from sul phate and chlo ride brines at the palaeovalley floor. Both the re de pos ited sed i ments and the brines must have come from the ad ja cent pla teaux and from a thrust-sheet top ba sin, ap proach ing from the south on top of the Cre ta ceous-Paleogene Carpathian flysch thrust wedge.

Discovery of the Badenian evaporites inside the Carpathian Arc: implications for global climate change and Paratethys salinity

“…It is easy to imagine the reworking of evaporites so that they do not leave much evidence behind in the geological record, as halite dissolves in water, while sulphates are soft and grind to nothing in a shallow water high energy environment. Recycling of evaporites is probably a more important process then thought before as it has been recorded from the East Slovakian Basin (Bukowski et al 2007), and from the Carpathian Foredeep (Kolasa & Slaczka 1985;Cendón et al 2004;Głuszyński & Aleksandrowski 2016) repeatedly. However, recognizing any original sedimentary structures of resedimentation might be difficult as evaporites are often tectonized also in Hungary (Palotai & Csontos 2012) following the fully-marine Badenian and preceding the very low-salinity Pannonian.…”

“…Salts and sulphates are both known to be easily recycled as observed at several places in the Paratethys (Kolasa & Slaczka 1985;Cendón et al 2004;Bukowski et al 2007;Głuszyński & Aleksandrowski 2016).…”

The Middle Miocene of the Fore-Carpathian Basin (Poland, Ukraine and Moldova)

“…According to this model, the deposition of evaporite facies was controlled by depth -Ca-sulphates in shallower and Nachlorides in deeper parts of the basin. This idea was also accepted by Połtowicz (1993), Bukowski (2011), and Głuszyński and Aleksandrowski (2016). Similarly Bąbel and Bogucki (2007), who applied limnological terminology to the evaporite basin, suggested a meromictic lake model for the basin, in which halite deposition was restricted to the deepest monimolimnion zone.…”

Salt tectonics in front of the Outer Carpathian thrust wedge in the Wieliczka area (S Poland) and its exposure in the underground salt mine

“…The PCF was overridden from the south, by up to 50 km, by the advancing Outer Carpathian thrust wedge, which resulted in the partial incorporation of the PCF's synorogenic Miocene fill in the thrust system (e.g. Oszczypko 1997, 1998, Krzywiec et al 2004, 2014, Oszczypko et al 2006, Głuszyński & Aleksandrowski 2016. This led to the subdivision of the PCF into two subunits: the inner PCF, which is situated beneath the Carpathian nappes, and the outer PCF, extending north of the Carpathians' margin (Oszczypko 1997, 1998, Oszczypko et al 2006.…”

“…Along the northern margin of the Outer Carpathians in Poland a zone of tectonized Miocene deposits crop out and this is distinguished as the Zgłobice Thrust Unit (ZTU, e.g. Kotlarczyk 1985, Połtowicz 1991, Krzywiec et al 2004, 2014, Żelaźniewicz et al 2011, Głuszyński & Aleksandrowski 2016. All the near-surface rock salt occurrences in the PCF, making a chain of separated salt bodies, are located within this tectonic unit.…”