To the Problem of Marine Transgressions and Situations of Sedimentation in Central and Northern Yakutia in Neo-Pleistocene
The problem of the Neo-Pleistocene paleography of the East Siberian Plain is considered using the example of natural complexes in Central and Northern Yakutia. The inconsistency of reconstructions of natural settings made by different researchers is shown. Some scientists write about the extensive polar glaciations of the Neo-Pleistocene covering, according to their data, the entire coast of the Arctic Ocean, others about large marine transgressions and regressions that led to periodic oods and dehumidication of vast intracontinental spaces. In addition, there are ideas about the so-called «subaerial history of the Pleistocene» in which the leading role was played by eolian processes.The distribution and structure of sandy strata of Central and Northern Yakutia conned to the Primorski lowlands of the Laptev and East-Siberian seas, the valley of the Middle and Lower Lena, the Vilyuy, Olenek, and Khatanga basins are analyzed. Their capacity, in some areas, does not reach hundreds of meters; however, the problem of the genesis of these deposits, despite the considerable successes of modern analytical methods for studying the morphology and mineralogy of sand grains, has not yet been solved. The current ideas about the origin of sand are contradictory. However, the connement of sand to the sides of river valleys and slopes of watersheds, the similarity of their granulometric and mineralogical composition may indicate a single factor that determines the facial conditions for their accumulation. These deposits, opening in the cliffs of high sand terraces, are characterized in the upper part of outcroppices by a distinct horizontal stratication, which may indicate their basin origin rather. Satellite images of Central Yakutia show clearly the spatial position of the loose sand-dune massifs in the basin of the river Lena and the Vilyuy Rivers. Sandy ridges tend to a certain area of basins, as if delineating the boundaries of the former water area of a large inland water body. It seems that the high position of the level of the former pond-liman basin with its periodic uctuations lasted more than one millennium, which contributed to the accumulation of signicant amounts of terrigenous deposits involved in the coastal-forming processes. Passive limnogenesis prevailed in the zone of shallow bays and lagoons, accompanied by the accumulation of an ice complex, which was widely spread on the accumulative plains of Central Yakutia. With the completion of the transgressive cycle, a key role in relief formation passed to subaerial-eolian processes.