Oxygen and carbon stable isotope records of the Lochkovian-Pragian boundary interval from the Prague Basin (Lower Devonian, Czech Republic)

摘要

Climate changes close to the Lochkovian-Pragian Event are still widely discussed. Carbonate delta O-18 and delta C-13 and conodont apatite delta O-18 from medial to distal carbonate ramp sediments were analysed to provide further stable isotope data from the stratotype area in the Prague Basin. The uppermost Silurian to lower Emsian delta O-18 trends are put into an updated conodont biostratigraphy framework. Carbonate delta O-18 and delta C-13 are discussed in the context of facies-dependent diagenesis. The delta C-13 pattern measured from different sections enables the correlation of intervals with development of different facies inside the Prague Basin. Positive delta C-13 shifts are often coupled with trends of decreasing computed gamma-ray (CGR) values interpreted as regressions, whereas negative delta C-13 shifts commonly coincide with opposite trends in CGR. The Lochkovian-Pragian boundary interval coincided with an increase in carbonate delta C-13 and an increase in the delta O-18 of conodont apatite and carbonate, which we interpret as consequence of climate cooling. Generally, the Lochkovian was warmer than the Pragian and earliest Emsian.