Academician Ridge is an underwater, structural high separating two of Lake Baikal'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 Olkhon ( rus, Ольхо́н, also transliterated as Olchon; bua, Ойхон, ''Oikhon'') is the third-largest lake island in the world. It is by far the largest island in Lake Baikal in eastern Siberia, with an area of . Structurally, it const ...

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 In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be ...

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 A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing Turbidites were ...

. Therefore, sedimentation on Academician Ridge is restricted to fine, continuous

hemipelagic Hemipelagic sediment, or hemipelagite, is a type of marine sediment that consists of clay and silt-sized grains that are terrigenous and some biogenic material derived from the landmass nearest the deposits or from organisms living in the water. He ...

sedimentation with dispersed coarse-grained sediment deposited by

ice rafting Ice rafting is the transport of various materials 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 wate ...

(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 A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

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

References

* * * * * {{cite journal , author = Mats, V.D. , author2=Khlystov, O.M. , author3=De Batist, M. , author4=Ceramicola, S. , author5=Lomonosova, T.K. , author6=Klimansky, A. , year = 2000 , title = Evolution of the Academician Ridge Accommodation Zone in the central part of the Baikal Rift, from high-resolution reflection seismic profiling and geological field investigations , journal = International Journal of Earth Sciences , volume = 89 , issue=2 , pages = 229–250 , doi=10.1007/s005310000094 Landforms of Siberia Lake Baikal Sedimentology Historical geology