Relics of marine bacterial coenoses from the Neoproterozoic Formations of the South margin of Siberian Platform

摘要

The ecobiological interpretation of the microfossils (M), considered in Acritarcha, from Neoproterozoic sediments of Southern margin of Siberian Platform has been carried out. The advantage of the studied strata is that they reflect the conditions of shelfs and more deep-sea sites. Morphological features of M determined the compairison to possible types of the recent bacteria whose metabolic properties mostly corresponded to the reconstructed biotopes. The characteristic features and a relationship with carbon-bearing matrix allowed us to speculate on attribution of the most part of M (Bavlinella Schep., etc.) to anaerobic, sulphate-reducing bacteriacoenosis and about their dwelling in varied settings. Orthorhombic shape of the forms Octoedrixium Rud are likely determined by the crystallization of the trapped sulfur and its later diffusion in the diagenesis from the cells of aerobic sulphur bacteria. The star-like forms Floris Stan, are similar in their habitat and morphology to the aerobic prosthecobacteria of recent water-bodies. The forms of two last-named groupings are found in shallow sediments. The organic-walled M, attributed to bacteria, preserve their volume and features in metamorphic conditions. To take into account this ability and to make natural systematic perspective of the group Acritarcha classification, its modified version is proposed.