Andrey Fedotov

A 1‐Myr record of paleoclimates from Lake Khubsugul, Mongolia

The ancient Lake Khubsugul in North Mongolia is situated at the far reach of moisture from the North Atlantic into continental Asia [Kuznetsova, 1978]. It is remote from the Pacific Ocean and shielded from the China Sea and the Indian Ocean by high mountains. Information on the paleoclimates in this territory is scarce and sometimes controversial. In winter of 2003, due to a joint project (Khubsugul Drilling Project or KDP) of the Siberian Branch of the Russian Academy of Sciences and the Academy of Sciences of Mongolia, a 53-m drilling core (KDP-1) of sediments of Lake Khubsugul was obtained. This article describes the first results of paleomagnetic and geochemical studies of this core, which was found to span the time interval of the last 1.05 Myr. The data suggest that global climate oscillations manifested themselves in repeated desiccation and filling of the lake due to changes in humidity.

Chronology of the Baikal Rift System

The deepest lake in the world, Lake Baikal, Russia, lies on the intracontinental Baikal Rift system (BRS) along with the nearby Lake Khubsugul in northern Eurasia. Many questions connected with the history of the development of BRS remain open, in particular the time and causes of the formation of the recent BRS morphology. Thus, the rate of the Indo-Asian collision, and the discovery of mantle plume intrusion on the large area of Northern and Central Mongolia and on the TransBaikal area in the vicinity of the rift, have been subjects of hot debate throughout the past 50 years of research on the formation of the intercontinental BRS. Studies by the authors of this article have focused on the southwestern BRS, particularly the Khubsugul Rift. Because of its submeridional trend, the Khubsugul Rift is believed to manifest various reactions when parameters of the tectonic stress field change due to the influence of the Indo-Asian collision in forming the northeast compression impact or of mantle plume intrusion that forms the northwest extension stress field.

Water motion as a transformation mechanism of algal communities structure in Lake Baikal

The diversity of algal communities of phytoplankton and meio-and macrophytes was investigated in Lake Baikal. Fragments of Spirogyra thallomes were recorded in the phytoplankton community of Southern Baikal, which had never been recorded before in its composition. It was also established that the structure of benthic algal communities changed in comparison with that in 2000 due to intense development of filamentous algae, particularly Spirogyra. Its lowest biomass was recorded in the surf zone and wave breaking, whereas the highest biomass was registered in the area of weakened effect of waves on the bottom. The cover percent of the bottom with filamentous algae in different areas of the coastal zone varied from 0 to 100%. Hydraulic characteristics of Spirogyra were the same as those of planktonic diatoms. The circulation currents and wave effect on the bottom favoured transfer and distribution of Spirogyra from the location of its intense development into the coastal area of Lake Baikal.