New biocenosis model of Vendian (Ediacaran) sedimentation basin of Podilia (Ukraine)

The aim of this study is to fully research all aspects of the distribution, development, conditions of burial and preservation of the Ediacaran biocomplex. Thiswork summarizes and extends all data on the unique Vendian invertebrates that are distributed in the natural and artificial outcrops of the Dniester River Basin within Podilia (Ukraine). One of the basic locations of the annual observation was a quarry of rubble stone production near the Dniester hydroelectric station-1, Novodnistrovsk city, which exposes a continuous section of the deposits of the Lomoziv, Yampil, Lyadova and Bernashivka Beds lying on a crystalline basement. This paper shows the outcomes of long-term fieldwork of the Upper Ediacaran which include deposits of the Mogyliv-Podilsky and Kanylivka Group. The researched section is characterized by its clastic composition and the absence of carbonate formations. The basic paleontological collection has more than two thousand specimens, for instance, the imprints of molluscous fauna, traces of their live activity, the remains of flora and fossils of a problematic nature. The most numerous and informative collection of these fossils is located in the stock of the Geological Museum of the Taras Shevchenko National University of Kyiv. The collection contains unique material, including a number of Ediacaran fossils described for the first time. On the whole within Podilia region, more than 100 species have been described in detail. The main areas of biota accumulation in the outcrops are associated with argillites, argillite-siltstones and their contact with sandstones. The best preservation of the imprints is detected in the boundary of facial transitions. Research has revealed that there is a decrease in the numerical and species composition of the molluscous biota, and the dynamic increase in evolution of burrowing organisms and plants within the Podilia Basin during the late Vendian. Such a phenomenon led to an environmental change, increase in oxygen and appearance of new groups of organisms that were subsequently displaced invertebrates. This occurred at the Precambrian/Cambrian transition, and in the geological literature is described as the «Cambrian explosion». Studies have found that the total number of taxonomic composition of the Eidacaran in Podilia is similar to the orictocoenosis of Southern Australia and the White Sea. Nevertheless, the Podilia biocomplex is more ancient than the Southern Australian and the White Sea, it is much younger than the Avallonian.