MICROFACIES AND PALEOALGOLOGICAL COMPLEXES OF CARBONATES OF THE UPPER ORDOVICIAN TACHALOV SECTION (WEST OF GORNY ALTAI)

The article presents the study results of carbonaceous rocks and taxonomic diversity of the Upper Ordovician calcareous algae of the Tachalov section left half, located on the left side of the same-name creek in the central district of the Charysh-Inya structure-facies zone of Gorny Altai. Six microfacies are distinguished in rocks: algal-bacterial boundstones, crinoid mudstones, crinoid-algal wackestones, polybioclastic wackestones, crinoid-algal packstone-wackestones and crinoid-algal packstones. Calcareous algae of the following genera were recorded in limestones: Proaulopora Volgdin, 1934 (Ms), Girvanella Nicholson et Etheridge, 1878, Vermiporella Stolley, 1893, Apidium Stolley, 1896, Ortonella Garwood, 1914, Contexta Gnilovskaja, 1972, Halysis Høeg, 1932, Rothpletzella Wood, 1948. It is found, that during the formation of biohermal buildups in more active hydrodynamics, different groups of calcareous algae react either by increasing species diversity (like green algae) or by increasing the number of organisms of the same species (like red algae).