PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE LOWER PALEOZOIC METAMORPHIC COMPLEX OF THE RUDAWY JANOWICKIE (WEST SUDETES, POLAND)
Abstract: The Lower Paleozoic Rudawy Janowickie Metamorphic Complex represents the eastern part of the Izera-Karkonosze Massif in the West Sudetes (NE Bohemian Massif). It comprises a nappe pile overthrust towards the NW onto the pre-Variscan continental basement of the Saxothuringian Basin. The complex consists of three units: (1) Leszczyniec Unit composed of metabasites and gneisses, (2) Izera-Kowary Unit consisting of gneisses and mica schists and (3) the South Karkonosze (Niedamirów) Unit consisting of greenstones and phyllites. These rocks underwent multistage deformation mostly accompanied by epidote-amphibolite grade metamorphism of the Late Devonian to Early Carboniferous age. Rock magnetic study revealed magnetic and hematite as carriers of remanence accompanied by maghemite and sometimes by goethite. Several high stability components of characteristic remanent magnetization (ChRM) of predominantly reversed polarity were found. The shallow directions of remanence were interpreted as Carboniferous overprint on the basis of the similarity of their pole position to the Carboniferous segment of the Apparent Polar Wander Path (APWP) for Baltica. The position of paleopoles derived from the steep directions corresponds well with the Silurian segment of the APWP for Baltica assuming the anticlockwise rotation of the Rudawy Janowickie Complex by the angle of ca. 90º. The paleolatitude derived from these directions after averaging corresponds well to the Silurian data for the Bohemian Massif. The possibly Early Paleozoic directions were found in different rock types: metabasites, gneisses and limestones from the Leszczyniec and Izera-Kowary Units. However, the scatter of the Kmax and ChRM along similarly oriented girdles may suggest that the deformation influenced the NRM directions.
MESOZOIC ALKALI LAMPROPHYRES IN VARISCAN GRANITOIDS OF THE MALE KARPATY AND NIZKE TATRY MOUNTAINS — GEOCHRONOLOGY AND GEOCHEMISTRY
Abstract: Mesozoic alkali lamprophyres from the Male Karpaty Mts and Nizke Tatry Mts granitoids have a similar petrographic pattern. The textures are phyric, with amphibole and clinopyroxene (Cpx) (and/or olivine) phenocrysts. Cpx are zonal and correspond to diopside. Amphibole are zoning too and correspond to kaersutites. On the basis of chemical composition they can be ranked with alkaline lamprophyres. The K/Ar age (approx. 100 Ma) of these dykes corresponds to the age of the Cretaceous alkaline basalt/basanite in the Krizna Nappe of the Central Western Carpathians.
RELATIONSHIPS BETWEEN VOLCANISM AND HYDROTHERMAL ACTIVITY IN THE TOKAJ MOUNTAINS, NORTHEAST HUNGARY, BASED ON K-Ar AGES
Abstract: Conventional K-Ar studies of volcanic rocks, rock-forming minerals and hydrothermal adularia and alunite from different volcanic centres of the Tokaj Mts indicate that volcanic activity took place between 15.2 and 9.4 Ma (Badenian-Sarmatian-Pannonian). In the northern part of the Tokaj Mts, ages for the relatively deeply eroded hydrothermal systems (Rudabanyacska and Telkibanya Au-Ag deposits and parts of the Regec caldera), formed mainly by the adularia-bearing low-sulphidation epithermal deposits, are between 13.0 and 12.2 Ma. These systems were developed within andesitic-dacitic volcanic centres with calderas and subvolcanic intrusions. In the southern parts of the Tokaj Mts (near Mad and in the Szerencs Hills region) exposures of hydrothermal systems mainly represent shallow acid-sulphate steam-heated zones of low-sulphidation-type systems, and the K-Ar ages are between 12.1 and 10.4 Ma. Radiometric ages also suggest that in some parts of this latter area, repeated hydrothermal activity occurred, suggesting that hydrothermal circulation developed in relation to different magmatic centres that were active at different times.
JOINTING IN THE SILESIAN NAPPE (OUTER CARPATHIANS, POLAND) - PALEOSTRESS RECONSTRUCTION
Abstract: The joint network in the Silesian Nappe is composed of a shear system (diagonal sets — SR, SL) — striking in the present position at high angles to map-scale fold axes, a single extension set T — striking sub-perpendicular to these axes, fold parallel joints L and L´ striking parallel or at small angles to map-scale fold axes. For paleostress reconstructions penetrative SR, SL and T joint sets were analysed from 197 outcrops. In the paleostres analysis the angular difference between the σHmax directions calculated from shear (SR, SL) and extension T joints is notable. The angular difference between these σHmax directions suggests that it is a result of a slight tectonic bending of the investigated Silesian Nappe arc, which took place between the nappe thrusting phase and the proceeding uplift phase of this part of the Outer Carpathians arc.
URGONIAN (EARLY CRETACEOUS) ECHINOIDS OF THE MIRDITA ZONE (SOUTHEAST ALBANIA)
Abstract: Remains of regular echinoids are described for the first time from Urgonian (Barremian-Aptian) strata of the central and southern Mirdita Zone (Albania). Based on spines, five species are distinguished, "Cidaris" strombecki Desor, ?Hirudocidaris gr. uniformis (Sorignet), "Cidaris" sp. 1, sp. 2 and sp. 3. Extremely rare coronal plates here described as "Cidaris" sp. are associated. The taphonomic features of these echinoid remains, the character of the associated fauna and the lithology correspond well to the shallow-water nature of the settings studied.
PONTIAN LEPTOCYTHERIDAE AND CYTHERIDEIDAE (OSTRACODA) SPECIES FROM THE EASTERN BLACK SEA REGION OF TURKEY
Abstract: Leptocytheridae Hanai and Cytherideidae Sars and their genera are well known biostratigraphically and chronostratigraphically in all of the Paratethys Basins during the Pontian age. The fauna described includes fourteen species, five known, five yet unnamed and four new species which belong to the above families. The species are Leptocythere (Amnicythere) multituberculata, Leptocythere (Leptocythere) cymbula, Euxinocythere (Maeotocythere) bosqueti, Cytherissa bogatschovi, Pontocythere bayramensis, Euxinocythere (Maeotocythere) krstici n.sp., Cyprideis krstici n.sp., Euxinocythere (Maeotocythere) pontica n.sp., Cytherissa pannonica n.sp., Cyprideis sp., Euxinocythere (Maeotocythere) sp., Leptocythere (Amnicythere) sp., Cytherissa sp.1 and Cytherissa sp. 2. On the basis of the ecological properties of Cyprideis, Leptocythere, Euxinocythere, Cytherissa and Pontocythere and the other observed Ostracoda in this faunal assemblage, the paleoenvironments include shallow marine, and littoral-brackish water (transitional) facies. All of these known species are related to the Eastern Paratethys (especially Euxinian and Caspian Basins) bioprovince.