NEOPROTEROZOIC (VENDIAN) PHYTOPLANKTON FROM THE SIBERIAN PLATFORM, YAKUTIA

Seven new species of comparatively large Neoproterozoic organic-walled acritarchs (Appendisphaera grandis, A. fragilis, A. tenuis, A.? tabifica, Cavaspina hasiconica, Tanarium irregulare, T. tuberosum) are reported from two drilling sites in Yakutia, eastern Siberia. Two previously known form-species (Cavaspina acuminata comb. nov. and Tanarium conoideum) are also emended. The acritarchs derive from siliciclastic rocks of the Khamaka Formation, the lowermost part of the Vendian to Cambrian sedimentary succession in the central part of the Siberian Platform. By comparison with assemblages from the Ediacaran Pertatataka Formation, the acritarchs in the Khamaka Formation are considered to indicate an Ediacaran age. The study confirms the broad environmental and geographical distribution of Neoproterozoic (late Vendian) plankton, and that they are diverse in rocks reflecting a range of depositional settings.