Variation in clastic input in the Berriasian of the Lower Sub-Tatric (Krížna) succession in the Tatra Mountains (Central Western Carpathians, Poland) : data from magnetic susceptibility and inorganic geochemistry

The paper deals with the age and palaeoenvironment interpretation of the Late Berriasian sedimentary transition from micritic calpionellid limestones to marls, corresponding to the passage from the Osnica Formation to the Kościeliska Marl Formation, Lower Sub-Tatric succession, Tatra Mts., Central Western Carpathians. Since only reliably dated sections are an appropriate basis for palaeoenvironmental study, the following pelagic and hemipelagic sections were chosen owing to enrichment in fine, clastic material and the existing biostratigraphic and magnetostratigraphic frameworks: Pośrednie III, Rówienka, Gładkie Upłaziańskie and Gęsia Szyja. The authors integrated and interpreted new, detailed data on magnetic susceptibility (MS), rock magnetism and element geochemistry from all of the sections. Well defined biostratigraphy permitted the testing of the potential of MS as a stratigraphic method. Owing to its close connection to selected terrigenous elements (e.g., Al, Th, Zr), MS could be used here as a proxy for detrital input into the basin. Its value as a correlation tool in a pelagic and hemipelagic setting was confirmed. MS permitted not only detailed correlation of the outcrops studied, but also the comparison of them with the Barlya section (Western Balkans) of the same age. This study proves that increased detrital input began in the Calpionellopsis simplex Subzone and continued into the lower part of the Calpionellopsis oblonga Subzone. It might be regarded as synchronous event within the Zliechov Basin and it is not everywhere correlated with the formation boundaries. The change in sedimentation was not only a local phenomenon. The onset of deposition of the terrigenous fraction can be identified in many sections of the Western Tethys. Two independent factors, regional regression and an increase in humidity might have contributed simultaneously to the increased detrital input in Late Berriasian time. However, this picture is further complicated by tectonic activity on local and regional scales.