PALYNOLOGICAL ASSEMBLAGES FROM THE MIDDLE EOCENE KUMA HORIZON AND ITS AGE ANALOGUES IN ADJACENT REGIONS

Abstract

The paper discusses the composition of organic-walled phytoplankton, spores, and pollen from the middle Eocene Kuma Horizon and its age analogues in adjacent parts of the East European platform, Scythian, and Turan plates. Anomalous contents of several taxons are established in the sediments that formed in anoxic environments. As compared with the organic-walled phytoplankton assemblages from the Kuma Horizon, those from the fine-grained clayey sediments of the upper Eocene Belaya Glina Horizon that accumulated in the open well-aerated sea basin with the normal salinity are characterized by the higher diversity and greater dispersion degree. Contrary to the Kuma palynological assemblages, the abundance of pollen and spores in the latter is below 5% of palynomorphs deposited in the shelf zone of the sea basin. Sediments of the Kuma Formation that were deposited in reducing environments are characterized by the extremely high content of amorphous organic matter (up to 95-98%) represented by detritus of the algal, ichthyiological, and partly cyanobacterial origin. The Kuma Horizon corresponds to two dinocyst subdivisions: the lower Areosphaeridium diktyoplokus-Dracodinium condylos and upper Rhombodinium perforatum-Rhombodinium porosum zones.