ALBERT

Description: The production of platform carbonates of the Manín Unit (Manín Straits, Central Western Carpathians) belonging to the Podhorie and Manín formations and formed by remains of rudists and benthic foraminifers (Urgonian-type carbonates), was previously assumed to terminate during the Aptian. First, we show that these deposits were primarily formed on the upper slope (Podhorie Formation) and in a fore-reef environment (Manín Formation). Second, biostratigraphic data indicate that the shallow-water production persisted up to the Albian, just as it did in another succession of the Manín Unit. The Podhorie Fm contains colomiellids (Colomiella recta, C. mexicana) and calcareous dinoflagellates (Calcisphaerula innominata) that indicate the Albian age. It also contains planktonic foraminifers (Ticinella roberti, Ticinella cf. primula, Ticinella cf. madecassiana, Ticinella cf. praeticinensis) of the Albian Ticinella primula Zone. The Podhorie Formation passes upwards into peri-reefal facies of the Manín Fm where we designate the Malý Manín Member on the basis of rudists shell fragments and redeposited orbitolinids. Microfacies associations share similarities with the Urgonian-type microfacies from Mediterranean Tethys and allow us to restrict the growth and the demise of the carbonate platform. δ13C and δ18O isotopes change over a broad range of both formations: δ13C is in the range +1.03 to +4.20 ‰ V-PDB and δ18O is in the range −0.14 to −5.55 ‰ V-PDB. Although a close correlation between δ13C and δ18O indicates diagenetic overprint, a long-term increase of δ13C can indicate a gradual increase in the aragonite production and/or increasing effects of oceanic water masses in the course of the Albian, prior to the final platform drowning. Carbonate platform evolution was connected with submarine slumps and debris flows leading to redeposition and accumulation of carbonate lithoclasts and bioclastic debris on the slope. Our study confirms that the growth of carbonate platforms in the Central Western Carpathians was stopped and the platform collapsed during the Albian, in contrast to the westernmost Tethys. A hardground formed during the Late Albian is overlain by Albian - Cenomanian marls of the Butkov Formation with calcisphaerulid limestones characterized by planktonic foraminifers of the Parathalmanninella appenninica Zone and calcareous dinoflagellates of the Innominata Acme Zone.

Description: A well preserved Upper Tithonian–Lower Berriasian Strapkova sequence of hemipelagic limestones improves our understanding of environmental changes occurring at the Jurassic/Cretaceous boundary in the Western Carpathians. Three dinoflagellate and four calpionellid zones have been recognized in the section. The onset of the Alpina Subzone of the standard Calpionella Zone, used as a marker of the Jurassic/Cretaceous boundary is defined by morphological change of Calpionella alpina tests. Calpionellids and calcified radiolarians numerically dominate in microplankton assemblages. The first occurrence of Nannoconus wintereri indicates the beginning of the nannofossil zone NJT 17b Subzone. The FO of Nannoconus steinmannii minor was documented in the lowermost part of the Alpina Subzone. This co-occurrence of calpionellid and nannoplankton events along the J/K boundary transition is typical of other Tethyan sections. Correlation of calcareous microplankton, of stable isotopes (C, O), and TOC/CaCO3 data distribution was used in the characterization of the J/K boundary interval. δ13C values (from +1.09 to 1.44 ‰ VPDB) do not show any temporal trends and thus show a relatively balanced carbon-cycle regime in sea water across the Jurassic/Cretaceous boundary. The presence of radiolarian laminites, interpreted as contourites, and relatively high levels of bioturbation in the Berriasian prove oxygenation events of bottom waters. The lower part of the Crassicolaria Zone (up to the middle part of the Intermedia Subzone) correlates with the M19r magnetozone. The M19n magnetozone includes not only the upper part of the Crassicollaria Zone and lower part of the Alpina Subzone but also the FO of Nannoconus wintereri and Nannoconus steinmannii minor. The reverse Brodno magnetosubzone (M19n1r) was identified in the uppermost part of M19n. The top of M18r and M18n magnetozones are located in the upper part of the Alpina Subzone and in the middle part of the Ferasini Subzone, respectively. The Ferasini/Elliptica subzonal boundary is located in the lowermost part of the M17r magnetozone. A little bit higher in the M17r magnetozone the FO of Nannoconus steinmannii steinmannii was identified.

Description: Magneto-, and isotope stratigraphy around the Jurassic/Cretaceous boundary in the Vysoká Unit (Malé Karpaty Mountains, Slovakia): correlations and tectonic implications Magneto- and isotope stratigraphic studies in the Vysoká Nappe (Hlboča section, Fatric Unit, Malé Karpaty Mts, Slovakia) were performed. A generally decreasing δ13C isotope curve is interpreted as a primary trend from the Late Oxfordian (3.3 ‰ V-PDB) to the Late Tithonian (1.8-1.4 ‰ V-PDB). Data from the Tithonian part of the Tegernsee Formation probably reflect "local" basin processes connected with the breccia formation in the latest Tithonian/earliest Berriasian and/or with possible diagenetic overprint. The C-isotope record of the Berriasian Padlá Voda Formation is more homogeneous (1.4-1.8 ‰ V-PDB) and assumed to be primary. Magnetostratigraphic investigations were focused on the Jurassic/Cretaceous (J/K) boundary strata. Upper Tithonian nodular limestones of the Tegernsee Formation differ substantially from Lower Berriasian calpionellid limestones of the Padlá Voda Formation in rock magnetic properties. Hematite is present in the Tegernsee Formation, while magnetite is the only magnetic mineral of the Padlá Voda Formation. Additionally, the latter formation contains superparamagnetic magnetite, which significantly influences its magnetic susceptibility. Correlation of normal and reversed magnetic intervals with the Late Tithonian global polarity time scale was supported by microfossil stratigraphy. M21n to M20n magnetozones were distinguished, including the short reversed Kysuca (M20n1r) Subzone within M20n. Interpretation of Lower Berriasian magnetostratigraphy was more complex due to presence of breccia horizons and a stratigraphic gap at the J/K boundary in the lower part of the Padlá Voda Formation embracing M19r and most of M19n magnetozones. This formation was also partially affected by remagnetization. Detailed correlation between the isotope- and magnetic stratigraphy of the Tithonian-Berriasian interval between Hlboča and Brodno sections is also complex due to J/K stratigraphical gap within the Hlboča section. The primary B component accounts for counter-clockwise rotation of the Vysoká Unit with a magnitude of ca. 50°. Since the paleodeclination of Paleogene and Karpatian-Eggenburgian rocks in the area is similar, the rotation must have taken place after Early Miocene. The paleoinclinations of several Upper Tithonian-Berriasian sections of the Central Western Carpathians and western part of the Pieniny Klippen Belt are consistent and indicate paleolatitude of 27-30°N.

Description: This paper discusses the results of a study of the Le Chouet section, its lithologies, facies, magnetic properties and fossil record (ammonites, calcareous nannofossils, calpionellids and calcareous dinoflagellates). Data obtained have been applied to give a precise biostratigraphy for this carbonate sequence as well as a paleoenvironmental reconstruction. Its relationship to magnetostratigraphy, based on a modern study of a French site, is important. Investigation of the micro- and macrofossils shows that the site comprises a sedimentary sequence in the Microcanthum to Jacobi ammonite Zones, and the Chitinoidella, Crassicollaria and Calpionella Zones. Several calpionellid and nannofossil bioevents have been recorded on the basis of the distribution of stratigraphically important planktonic organisms. The site allows us to calibrate the levels of various biomarkers and biozonal boundaries, and correlate them with the magnetozones M20n, M19r and M19n.

Description: Terminal Triassic environmental changes are characterized by an integrated study of lithology, litho- and cyclostratigraphy, paleontology, mineralogy, geochemistry and rock magnetism in the Tatra Mts. The Carpathian Keuper sequence was deposited in an arid environment with only seasonal rivers, temporal lakes and swamps with scarce vegetation. Combination of a wide range of δ18O values (-0.7 to + 2.7) with negative δ13C values documents dolomite precipitation either from brackish or hypersaline lake water, or its derivation from pore water comparably to the Recent Coorong B-dolostone. Negative δ13C values indicate microbial C productivity. Rhaetian transgressive deposits with restricted Rhaetavicula fauna accumulated in nearshore swamps and lagoons. Associations of foraminifers, bivalves and sharks in the Zliechov Basin were controlled by physical factors. Bivalve mollusc biostromes were repetitively destroyed by storms, and temporary firm bottoms were colonized by oysters and burrowers. Subsequent black shale deposition recorded input of eolian dust. Bottom colonization by pachyodont bivalves, brachiopod and corals started much later, during highstand conditions. Facies evolution also revealed by geochemical data, C and O isotope curves reflect eustatic and climatic changes and help reconstruct the evolution of Rhaetian marine carbonate ramp. The Fatra Formation consists of 100 kyr eccentricity and 40 kyr obliquity cycles; much finer rhythmicity may record monsoonlike climatic fluctuations. Fluvial and eolian events were indicated by analysis of grain size and content of clastic quartz, concentrations of foraminiferal (Agathammina) tests in thin laminae indicates marine ingression events. Magnetic susceptibility (MS) variations reflect the distribution of authigenic and detrital constituents in the sequence. Increasing trend of MS correlates with the regressive Carpathian Keuper sequence and culminates within the bottom part of the Fatra Formation. Decreasing trend of MS is observed upwards the transgressive deposits of the Fatra Formation.