PRECAMBRIAN MICROFOSSIL-CHARACTERIZED BIOTOPES FROM THE SOUTHERN MARGIN OF THE SIBERIAN CRATON

Abstract

The microfossils examined in acritarchs from the Neoproterozoic rocks in the southern margin of the Siberian craton have been ecobiologically interpreted. The studied sequences are of particular interest as they represent different sedimentation stages of an evolving marine basin. The conditions of sedimentation were reconstructed and the microfossil assemblages were recognized in three areas of the Sayany-Baikal fold system (SBFS). The ecological and biological affiliation of a part of the organic-walled microfossil morphotypes was revealed owing to the reconstructions and actuopaleontological comparison. Members of green and brown algae, dinoflagellates, and bacteria assemblages from different depths of the paleobasin have been differentiated. Most of organic-walled forms from the SBFS have the property of retaining volume and characters in fossil remains. A modified variant of the acritarch classification is proposed considering this capacity and in an effort to develop in the future a natural classification scheme.