PERIODICITY OF DEPOSITION IN THE SILURIAN AND RELATIONSHIPS OF GLOBALGEOLOGICAL EVENTS IN THE MIDDLE PALEOZOIC OF THE SOUTHWESTERN MARGIN OF THE SIBERIAN CONTINENT

Alignments of the Altai Siberian stratigraphical scale, that is the re ference one for entire south of the Western Siberia, and Standard scal e for this System are clarified, The cyclic structure of the succesion is analyzed, and four transgressive-regressive cycles combined by pai rs in two depositional phases A and B are recognized. It is shown that these cycles are connected with eustatic sea level changes. ''Deepeni ngs'' of the basin at starts of the first three cycles are estimated a t no less than 60-100 m. Anoxia appeared at these eustatic rises. They are marked by sedimentary and simultaneously biological events: Chine ta (persculptus) Syrovaty (sedgwicki), and Chesnokovka (Cyrtograptus). General preliminary analysis is given to a single Silurian-Devonian s uccesion of eustatic cycles established in challow shelf facies in sou th of the western Siberia. Cycles of three orders and periodicity in c ombination of one-order cycles are revealed. It is established that th e regularities of eustatic fluctuations of sea level, fixed in sedimen tation, completely agree with regularities in evolution of dechenelloi d trilobites, being their mirror reflection. The conclusion is made th at the factors determining parallel character of processes of depositi on and evolution of benthic organisms, like trilobites, are the same.