Academician Ridge is an underwater, structural high separating two of Lake Baikal

Lake Baikal

Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...

's three basins, the Central and North basins. Situated in the central part of the Baikal Rift, it serves as an "accommodation zone", transferring "motion between faults of similar displacement but different orientation" (Hutchinson et al., 1992). The ridge is bounded by two large normal faults, the Primorsky Fault on the northwest and the Olkhon Fault on the southeast, and an oblique-slip fault, the Academician Fault, that runs along the crest of the ridge. The margins of the ridge, Olkhon Island to the southwest and the Ushkanie Islands to the northeast, are above lake level while the center of the ridge is submerged to depths of 350-400 m (Kuzmin et al., 2000).

Academician Ridge represents a unique sedimentary environment within Lake Baikal. The depths of the two basins it separates, about 900 m in the North Basin and about 1600 m deep in the Central basin, isolate the ridge from mass-flows and turbidites. Therefore, sedimentation on Academician Ridge is restricted to fine, continuous hemipelagic

Hemipelagic

Hemipelagic sediments are those deposited slowly, but not as slowly as pelagic sediments. The sediments deposited on continental shelves and rises, frequently referred to as hemipelagic sediments, ordinarily accumulate too rapidly to react chemically with seawater. In most cases, individual grains...

 sedimentation with dispersed coarse-grained sediment deposited by ice rafting

Ice rafting

Ice rafting is the transport of various material by ice. Various objects deposited on ice may eventually become embedded in the ice. When the ice melts after a certain amount of drifting, these objects are deposited onto the bottom of the water body, e.g., onto a river bed or an ocean floor. These...

 (Kuzmin et al., 2000). The stratigraphy observed in boreholes drilled into Academician Ridge shows that the upper sequence of continuous hemipelagic deposits, which are consistent with a bathymetric high in a deep lacustrine

Lacustrine

Lacustrine means "of a lake" or "relating to a lake".Specifically, it may refer to:*Lacustrine plain*Lacustrine delta-Fish:*Lacustrine goby , a type of small fish found in Philippine waters belonging to the Gobiidae family, known in Tagalog as dulong-See also:*Fluvial - of or relating a...

environment, is underlain by a lower sequence that is consistent with prograding, deltaic deposits in a shallow-water environment (Mats et al., 2000). This change from a shallow-water environment to a deep-water environment represents two things: one, that Academician Ridge experienced gradual flooding and, two, that the presence of a lake in the North Basin occurred long after the presence of a lake in the Central and South basins first occurred (Mats et al., 2000).

Academician Ridge also plays an important role in deep-water mixing processes and the circulation of bottom currents. Water with a higher salinity than the lake is fed to the Central Basin by the Selenga River. In contrast, the Upper Angara River feeds the North Basin with fresh water. The result is dense, more saline surface waters from the Central Basin flowing northeast and passing over Academician Ridge into the less dense, less saline waters of the North Basin. The saline surface water then sinks along the density gradient to replenish the deep bottom waters of the North Basin (Francus and Karabanov, 2000; Colman et al., 2003).

Timeline of Major Events

Late Oligocene-Early Miocene	formation of a deep lake in the South and Central Basins
Middle-Late Miocene	uplift and formation of Academician Ridge
Late Miocene	gradual flooding of Academician Ridge
latest Pleistocene	complete submergence of Academician Ridge