RESULTS OF 2D BALANCING ALONG 20° AND 21° 30’ LONGITUDE AND PSEUDO-3D IN THE SMILNO TECTONIC WINDOW: IMPLICATIONS FOR SHORTENING MECHANISMS OF THE WEST CARPATHIAN ACCRETIONARY WEDGE
Abstract: The restoration of structures along two balanced cross sections through the West Carpathian accretionary wedge and the pseudo-3D restoration in the Smilno tectonic window area shows that various defined units are parts of the Magura and Silesian sedimentary successions. The shortened Magura and Silesian successions were detached at the base of the Upper and Lower Cretaceous sediments, respectively. The interpretation of the structural and sedimentological data places the Magura depositional area as the southwestern neighbour of the Silesian depositional area. Both areas were shortened during the Upper Eocene–Oligocene. The Magura area was shortened strongly owing to the collision between the Alpine orogen and the European Platform. The Silesian area was shortened gently due to the subduction of the oceanic plate attached to the European Platform. The Magura Unit was thrust over the Silesian sediments much later during the Miocene as an out-of-sequence oblique thrust. The Miocene shortening of the Magura Unit and the oblique closure of the Silesian portion of the basin caused a significant contribution to the orogen strike-parallel sinistral strike-slip faulting in the deformation of the accretionary wedge. The general shortening mode was a piggy-back process. Thrust geometries were created by both the fault-bend and fault-propagation folding. The frequent out-of-sequence thrusting is caused by the friction/erosion interplay. Variations in friction along the basal thrust include low friction, documented by subhorizontal veins with vertically grown fibers and long thrust sheets, medium friction, indicated by the duplexing, and high friction indicated by antiformal stacks. Basement steps along pre-existing rifting-related normal faults caused complications in the wedge geometry. The step perpendicular to the tectonic transport caused the development of the antiformal stack, the oblique step caused the sinistral transpression.
EXTREMELY ISOTOPICALLY HEAVY SULPHUR IN BARITE CONCRETIONS FROM SLOVAKIA
Abstract: Extreme values of δ34S: +105.3 ‰, +105.2 ‰, +87.9 ‰, +87.2 ‰ and +79.7 ‰ were determined in barite concretions from the Aptian-Lower Albian marly limestone of the Krizna Nappe of the Western Carpathians, Slovakia. The phases relation in inclusions from these concretions, and the results of thermo-vacuometric impulse decrepitation analyses indicate temperatures of 50–60 °C, which correspond mostly to secondary inclusions. For the purpose of comparison, barite concretions from Rohoznik, Slovakia, from Gaiseltal, Germany, and from Havana, Cuba, were analyzed. Barite concretions with extremely high δ34S values were formed during late diagenesis of organic matter-rich sediment in the depth range of very low pore water sulphate concentrations, below the sulphate reduction zone.
RADIOLARIA FROM THE UPPER CENOMANIAN–LOWER TURONIAN DEPOSITS OF THE SILESIAN UNIT (POLISH FLYSCH CARPATHIANS)
Abstract: Upper Cenomanian to lower Turonian deposits of the Silesian Unit of the Polish Flysch Carpathians comprise a characteristic interval of green and black shales with manganese concrections, tuff and bentonites. These strata are not only distinctive lithologically, but also contain a rich radiolarian fauna. Thirty-five species of Radiolaria have been identified. Spherical cryptothoracic and cryptocephalic Nassellaria dominate in the assemblage, especially species such as Holocryptocanium barbui, H. tuberculatum, Hemicryptocapsa prepolyhedra and H. polyhedra. The systematic description of fifteen species belonging to order Spumellaria and twenty species of Nassellaria is presented herein.
VOLCANIC EVOLUTION AND STRATIGRAPHY OF THE MIOCENE BÖRZSÖNY MOUNTAINS, HUNGARY: AN INTEGRATED STUDY
Abstract: The Middle Miocene volcanic evolution of the Börzsöny Mountains, North Hungary, is presented, correlating new volcanological, petrological, geochemical, geophysical and paleontological data and establishing a detailed stratigraphy on the basis of additional K/Ar radiometric and paleomagnetic measurements. For the earliest volcanic activity, previous biostratigraphy showing an Early Badenian age has been confirmed and precisely defined by paleomagnetic investigations. The first-stage volcanic formations (16.5–16.0 Ma), deposited in a shallow marine environment, include resedimented, syn-eruptive, garnet-bearing dacitic volcaniclastics (originating mostly from small-scale ignimbrite eruptions) and coeval, garnet-bearing dacitic lava domes, sometimes with their volcaniclastic aprons. As the eruptions filled the marine basin, subaerial dacitic-andesitic volcaniclastics, comprising minor ignimbrites and different types of debris-flow deposits were also deposited. A part of the latter may have been related to the formation of two or three medium-sized calderas. The second stage (16.0–14.5 Ma) was characterized by andesitic lava dome activity terminated by a hydrothermal event. During the first half of this stage, a ca. 30° CCW rotation occurred. The third stage produced the most voluminous, moderately explosive, andesitic — basaltic andesitic High Börzsöny subaerial lava dome complex erupting up to the Badenian/Sarmatian boundary (ca. 13.7 Ma). Correlation of K/Ar geochronological and volcanological data shows that lava dome activity of the second and third stage may have been coeval with marine sedimentation in the southern Börzsöny.
NEOLITHIC/AENEOLITHIC BLUESCHIST AXES: NORTHERN SLOVAKIA
Abstract: In a set of stone artefacts from sites located in the Popradska kotlina Basin and in the County of Spis (northern Slovakia) we, among others, also identified axes made from blueschist. We consequently studied four of them using electron microprobe. Blueschists, raw material of mentioned axes, are composed of glaucophane, omphacite, garnet, albite, zoisite and other minerals in a subordinate amount. The composition of genetically significant blueschist phases is used to discuss the provenance of this raw material type. Comparing the presented composition of the blueschist mineral with those of the blueschist bodies known in surrounding geological units we incline to derive the raw material of the blueschist implements found in northern Slovakia from the blueschist occurrences in the Mesozoic Meliata Unit (southeastern Slovakia).