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November, 20, 2016

Origin and History of Lake Baikal

This unique lake has always been an area of great debate among scientists. It is the deepest lake on planet Earth and the largest reservoir of fresh water.

Experts are still unable to determine the exact age of the lake - supposedly 25-35 million years, which is another mystery since lakes exist for about 10-15 thousand years and then turn into a swamp or dry out completely. Baikal, however, is not aging - on the contrary, researchers note that the process of formation of the unique lake is not yet finished.

The banks of the lake diverge at a rate of 2 cm per year, which is why many experts hypothesize that Baikal is a nascent ocean.

Another widely-discussed theory, developed by doctor of Geological-Mineralogical Sciences A. Tatarinov, suggests that the lake could be relatively young. And there is evidence, albeit indirect, that confirms it. After studying the material composition of the sediments and physicochemical processes in them, the researchers came to the conclusion that the shoreline of the lake is about 8000 years old, while the lake's deep-water area is about 150,000 years old.

There is still speculation about the lake’s origin. 

Some believe that it was formed as an ancient rift valley when three individual basins united in the Precambrian period. In the initial stages of formation, the basins represented three bays of a Cambrian sea. The sea later retreated, which turned the bays into closed-off bodies of water. Over the subsequent years, erosion destroyed the barriers between them, resulting in the formation of a large basin.

Others suggest that the Baikal basin was formed as a result of subsidence which is still ongoing.

Many scientists explain the formation of Baikal by its location in the zone of an ancient tectonic fault; others assume there must be a giant fault in the Earth mantle below the lake; and others believe that the formation of the basin is connected with the tectonic processes (phenomena, such as earthquakes, that take place during crustal movements) resulted from the continental drift of Eurasia.

Recent results obtained by the method of seismic tomography in the Laboratory of Geodynamics and Paleomagnetism of the Institute of Geology, Siberian Branch of RAS, allowed scientists to take a fresh look at this problem and propose a scheme of formation and evolution of the Baikal region.

Thus, there is still no accurate data on the time of formation of Lake Baikal. There is also no evidence to suggest that it did not already exist in the Cenozoic era.

The lake is located right in the heart of the Baikal rift zone - a fault in the earth's crust of the continental Eurasia. One of the consequences is high seismic activity, and the local heat flow anomalies within the limits of the Baikal basin are likely to be related to thermal dykes penetrating to different depths in the subsurface layer, deforming and breaking it. The process may have led to the formation of the mountain range surrounding the lake.

Фото
There is no doubt, however, that the lake is located in a rift basin and is structurally similar to the Dead Sea basin. Some researchers attribute the formation of the lake to its location in the tectonic fault zone, others suggest the presence a mantle plume under the lake, and some believe the formation of the depression was caused by passive rifting a result of collision of the Eurasian plate and the Indian subcontinent. 
 

Whatever it was, the transformation of the lake continues - earthquakes still occur around the lake. There are suggestions that the subsidence troughs are connected with the formation of pockets of vacuum due to the outpouring of basalt on the surface (the Quaternary period).

In 1996, Lake Baikal was listed as a UNESCO world heritage site.

Baikal is situated almost in the very center of Asia. With a length of 636 km, a width of 81 km, and the coastline length of about 2000 km, it has a total area of 31,500 sq. km, which makes it the second largest lake in the world, after the Caspian, Victoria, Tanganyika, Huron, and Superior lakes. However, it is still the deepest (with a maximum depth of 1637 m and an average depth of 730) lake in the world. And of course, the largest freshwater lake by volume, containing 20% of world’s total fresh water and 80% of Russia’s freshwater resources. It also contains more water than all five of the Great American lakes put together.

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