FACIES AND SEDIMENTARY ENVIRONMENT OF THE CARBONATE-DOMINATED CARPATHIAN KEUPER FROM THE TATRICUM DOMAIN: RESULTS FROM THE DOLINA SMYTNIA VALLEY (TATRA MTS, SOUTHERN POLAND)

摘要

The paper focuses on an interpretation of sedimentary and early diagenetic environment in the carbonate-dominated uppermost Ladinian-Norian succession from the Tatricum domain of the Tatra Mountains as well as its controlling factors. Limestones with cherts are the product of pedogenic processes, formed during long-term exposures of carbonate substrate. Chalcedony cherts were formed during relatively early diagenesis of pedogenic limestones. Dolostones and dolomitic mudstones were deposited in a kind of salt marshes. Pseudomorphs after sulfates and absence of benthic fauna indicate increased salinity and intensive evaporation. Additionally, low TOC concentration suggests a low productivity in the basin. On the contrary, stable isotope signals indicate that the sedimentary environment was strongly affected by meteoric water. Moreover, 18O and concentration of Sr suggest that dolostones were formed under the influence of both marine and meteoric waters. Dolomitic mudstones could be deposited in a salt-marsh environment fed by distal sheet floods. Components of palynological material and organic compounds in black dolomitic mudstones indicate the terrestrial origin of organic matter. Dolomitic regoliths were formed as the result of subaerial exposure and karstification of dolostones. Coarse-grained siliciclastics and variegated mudstone are interpreted, respectively, as a fluvial channel and flood plain facies of ephemeric fluvial environment. Sedimentary environment of the Keuper sediments was controlled by two main factors synsedimentary tectonic movements and climate changes. In the latest Ladinian, the Middle Triassic carbonate platform was emerged, what resulted in the development of palaeosols. Block tectonic movements affected the Tatricum Basin in Keuper time. Horsts were emerged, whereas troughs were filled with fluvial or salt marsh sediments. Intensive tectonic movements are suggested by seismic-generated slumps and abrupt facies changes. More intensive chemical weathering and intensive contribution of pure siliciclastics suggest climate pluvialization in late Ladinian-early Carnian time. On the contrary, domination of physical weathering indicates the aridization of climate in late Carnian?-Norian time. The upper Carnian?-Norian succession was formed in hot and semi-arid climate conditions. Long-term climate changes was masked by short-term climate fluctuations. Geochemical indicators suggest that dolostones represent more humid periods, whereas dolomitic mudstones relatively dry periods.