Quantitative allochem compositional analysis of Lochkovian-Pragian boundary sections in the Prague Basin (Czech Republic)

摘要: Abstract Quantitative allochem compositional trends across the Lochkovian-Pragian boundary Event were examined at three sections recording proximal to more distal carbonate ramp environment of Prague Basin. Multivariate statistical methods (principal component analysis, correspondence cluster analysis) point-counted thin section data used reconstruct facies stacking patterns and sea-level history. Both closed-nature percentages their centred log-ratio (clr) coordinates used. these approaches allow for distinguishing lowstand, transgressive highstand system tracts within Praha Formation, which show gradual transition from crinoid-dominated deposited above storm wave base dacryoconarid-dominated deep-water below base. also indicate progradative-retrogradative in macrolithologically monotonous shallow-water succession enable its stratigraphic correlation with successions deeper-water environments. Generally, clr are sensitive subtle changes composition comparison results based on raw data. A heterozoan-dominated association environments Formation supports assumed by previous authors.