Thermal Maturity of the Grajcarek Unit (Pieniny Klippen Belt): Insights for the Burial History of a Major Tectonic Boundary of the Western Carpathians

The Grajcarek Unit of the Pieniny Klippen Belt (PKB), at the boundary between the Central (Inner) and Outer Carpathians, resulted from the convergence of the ALCAPA (the Alps–Carpathians–Pannonia) block and European plate. The strongly deformed slices of the Grajcarek Unit consist of Jurassic–Cretaceous sedimentary rocks associated with Late Cretaceous–Middle Palaeocene synorogenic wild-flysch, and sedimentary breccias with olistoliths. Maximum burial temperatures and burial depths were estimated based on vitrinite reflectance data. The vitrinite reflectance values were wide scattered through the Grajcarek sedimentary succession, especially in the flysch formations. This is attributed mainly to the depositional effects that affected the vitrinite evolution. The determined maximum burial temperatures were interpreted due to the regional compression controlled by tectonic burial coeval with thrusting and strike-slip faulting. The regional vitrinite reflectance variations might estimate cumulative displacement around the NNW–SSE and oriented the strike-slip Dunajec fault, which is a continuation of the deep fracture Kraków–Myszków fault zone.

Formation of a Composite Albian–Eocene Orogenic Wedge in the Inner Western Carpathians: P–T Estimates and 40Ar/39Ar Geochronology from Structural Units

The composite Albian–Eocene orogenic wedge of the northern part of the Inner Western Carpathians (IWC) comprises the European Variscan basement with the Upper Carboniferous–Triassic cover and the Jurassic to Upper Cretaceous sedimentary successions of a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated evolutionary model for principal structural units of the orogenic wedge (i.e., Fatricum, Tatricum and Infratatricum) based on new and published white mica 40Ar/39Ar geochronology and P–T estimates by Perple_X modeling and geothermobarometry. The north-directed Cretaceous collision led to closure of the Jurassic–Early Cretaceous basins, and incorporation of their sedimentary infill and a thinned basement into the Albian–Cenomanian/Turonian accretionary wedge. During this compressional D1 stage, the subautochthonous Fatric structural units, including the present-day higher Infratatric nappes, achieved the metamorphic conditions of ca. 250–400 °C and 400–700 MPa. The collapse of the Albian–Cenomanian/Turonian wedge and contemporary southward Penninic oceanic subduction enhanced the extensional exhumation of the low-grade metamorphosed structural complexes (D2 stage) and the opening of a fore-arc basin. This basin hemipelagic Coniacian–Campanian Couches-Rouges type marls (C.R.) spread from the northern Tatric edge, throughout the Infratatric Belice Basin, up to the peri-Pieniny Klippen Belt Kysuca Basin, thus tracing the south-Penninic subduction. The ceasing subduction switched to the compressional regime recorded in the trench-like Belice “flysch” trough formation and the lower anchi-metamorphism of the C.R. at ca. 75–65 Ma (D3 stage). The Belice trough closure was followed by the thrusting of the exhumed low-grade metamorphosed higher Infratatric complexes and the anchi-metamorphosed C.R. over the frontal unmetamorphosed to lowest anchi-metamorphosed Upper Campanian–Maastrichtian “flysch” sediments at ca. 65–50 Ma (D4 stage). Phengite from the Infratatric marble sample SRB-1 and meta-marl sample HC-12 produced apparent 40Ar/39Ar step ages clustered around 90 Ma. A mixture interpretation of this age is consistent with the presence of an older metamorphic Ph1 related to the burial (D1) within the Albian–Cenomanian/Turonian accretionary wedge. On the contrary, a younger Ph2 is closely related to the late- to post-Campanian (D3) thrust fault formation over the C.R. Celadonite-enriched muscovite from the subautochthonous Fatric Zobor Nappe meta-quartzite sample ZI-3 yielded a mini-plateau age of 62.21 ± 0.31 Ma which coincides with the closing of the Infratatric foreland Belice “flysch” trough, the accretion of the Infratatricum to the Tatricum, and the formation of the rear subautochthonous Fatricum bivergent structure in the Eocene orogenic wedge.

Jurassic evolution and the structure of the central part of the Pieniny Klippen Belt (Carpathians) in Poland – new insight from the Czertezik Succession type area

The Czertezik Succession of the Pieniny Klippen Belt in Poland is assigned herein to its type area of occurrence – the main Pieniny Range, between Zamkowa Góra and Czertezik mounts. The reworked deposits of uppermost Pliensbachian, Toarcian and possibly Aalenian to lowermost Bajocian discovered in crinoidal limestones which indicate redeposition processes, especially during the Bajocian, are considered to be clearly important for reconstructing the depositional history. The redeposited Pliensbachian is represented by clasts of spotty limestones, the Toarcian by ferruginous grains and fragments of crusts/large oncoids of the ammonitico-rosso type (?Adnet Fm.), whereas the Aalenian and lowermost Bajocian is possibly represented by clasts of siliciclastic deposits and phosphatic nodules. This part of the succession resulted from the activity of rifting phases at the end of the Early Jurassic, and in the Bajocian, which caused the development of the special sedimentary environments typical of the Czertezik Succession. The younger Middle to Late Jurassic deposits represented by nodular limestones, radiolarites and micritic well-bedded limestones show a less distinct facies pattern, which is in part similar to that of other successions of the Pieniny Klippen Belt, although some rock-units such as the newly established Zamkowa Góra Bed, revealing the continuation of redeposition processes, remain specific to the Czertezik Succession. The Jurassic structure of the central part of the Pieniny Klippen Belt in Poland is revised due to the introduction of the Czertezik Ridge as a new palaeogeographic unit being the place of deposition of the Czertezik Succession. The revised position of the deposits shifts the structural affinity of the Czertezik Succession from the Subpieniny Nappe to the base of the Pieniny Nappe sensu Uhlig, 1907, and implies its closer palaeogeographic position to the Branisko–Pieniny successions than to the Czorsztyn–Niedzica successions as has been interpreted so far.

Last scene in the large scale rotations of the Western Carpathians as reflected in paleomagnetic constraints

This paper provides an overview of the paleomagnetic results which constrain the post-Paleogene tectonic development of the Western Carpathians. A group of these results are relevant to the last stage of the Tertiary folding and thrusting of the Silesian, Dukla and Magura nappes of the Outer Western Carpathian and were obtained from Paleogene-Lower Miocene flysch sediments. Both the pre- and post-folding remanences indicate about 50° CCW vertical axis rotation with respect to the present orientation. This is about a 60° rotation relative to stable Europe. It follows that the general orientation of the Silesian and more internal nappes were NW-SE, at least until the mid-Miocene. The CCW vertical axis rotation was co-ordinated with that of the Central Carpathian Paleogene Basin. The termination of the rotation can be estimated from the paleomagnetic data available from the Pieniny andesites which intruded the Pieniny Klippen Belt and the southern part of the Magura Nappe as well as from those obtained for the Neogene intramontane basins which opened up in the Outer and in the Central Western Carpathians. The paleomagnetic vectors for the andesites form two groups. The first group suggests about 45° CCW rotation relative to north, while the second shows no rotation. At the present stage of our knowledge it seems likely that some of the andesite bodies were intruded around 18 Ma, which is the oldest isotope age for the intrusions of the Wżar Mts, while some other bodies could have been emplaced after the rotation, around 11 Ma, which is the youngest isotope age for the Brijarka quarry. Vertical axis CCW rotation was also observed on sediments older than 11.6 Ma in the Orava-Nowy Targ Intramontane Basin which saddles the Magura Nappe and the Central Carpathian Paleogene Basin. However, this rotation was related to fault zone activity and was not attributed to the general rotation of the Outer Western Carpathian nappe system. Paleomagnetic results from the Nowy Sącz Intramontane Basin, which opened over the Magura Nappe, and those for the Central Western Carpathian Turiec Intramontane Basin do not indicate vertical axis rotation. In the first case, the loosely controlled age limit of the termination of the rotation is around 12 Ma. Well constrained results from the second basin imply that the rotation was definitely over by 8 Ma. Based on the above observations, and aware of the problem of often loose age control on the formation and deformation of the deposits of the intramontane basins, it is tentatively concluded that the large scale CCW rotation of the Central Western Carpathians, together with the Magura, Dukla and Silesian nappes, must have started after 18 Ma and terminated around 11 Ma.

New kingenoid (Terebratellidina) brachiopods with larger body sizes from the Early Cretaceous of Zengővárkony (Mecsek Mountains, Hungary)

The small, Lower Cretaceous, iron ore deposit at Zengővárkony (Mecsek Mountains, southern Hungary, Europe) contains new brachiopod taxa of kingenoid relationships. Dictyothyropsis vogli, Zittelina hofmanni, and Smirnovina ferraria are described as new species from late Valanginian to earliest Hauterivian strata. The new taxa strengthen the presence of Early Cretaceous biogeographical connections with the Western Carpathians and the Pieniny Klippen Belt of southern Poland. The newly described taxa have significantly larger dimensions than their closest relatives from the type localities, which is in line with previous research on brachiopods from this environment. These brachiopods lived in a nutrient-rich, unique environment related to iron-ore deposition linked to former hydrothermal activity on the seafloor that might have contributed to the large size of these brachiopods. Larger than normal rhynchonellide and terebratulidine brachiopods have previously been recorded from this locality.UUID: http://zoobank.org/353882-2838-4eb7-b21a-8cc665d13408