Climate variability in the Stephanian B based on environmental record of the Mšec Lake deposits (Kladno–Rakovník Basin, Czech Republic)

摘要: Abstract In the Stephanian B in eastern equatorial Pangaea, a large freshwater lake was formed continental basins of west, central and northeast Bohemia, Czech Republic with total area estimated at 5000–10,000 km 2 lifetime 50 to 500 ky. Its size exceeded that any Permian–Carboniferous European period so far described. Continual sedimentation organic-rich, seasonally laminated clayey–silty deposits produced unique high-resolution record part climate studied region. An extraordinarily trophic web fish assemblages also proves temporal stability this meromictic oligotrophic lake. The hydrology inferred from chemical isotopic analyses autochthonous carbonates, particularly siderite, analysis organic matter. environmental weathering conditions watershed were palynospectra detrital clay minerals. passed through several stages development including an initial highstand peak productivity, stepwise increase mineralization accompanying gradual regression, lowstand middle its lifetime, partial recovery, then final transition shallow lacustrine-deltaic system. Lake regression triggered by long-term decrease P/E ratio coupled increasing seasonality accompanied intensity drainage basin. Considerable vegetation response fluctuating levels suggests complex changes. During highstand, abundant diversified xerophilous elements prevailed, spores ferns prevailed during regressive episode, lycopsids abruptly increased remained dominant second highstand. Final system associated pronounced sphenopsids ferns. These changes can be attributed Milankovitch-like change warm–wet warm–seasonal dry, may have been responsible for cyclothems. entire more humid than preceding Barruelian subsequent C basins, thus revealing cycle timescale million years, which is discussed relation southern Gondwana ice sheet stability.