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Origin & Development |
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History of Lake Baikal |
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Lake Baikal Climate |
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Fauna & Vegetation |
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Water of Lake Baikal |
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Recreational Areas |
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People of Lake Baikal |
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Baikal History & Formation Mechanism
Geological and Geophysical Data
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Geologists believe that the Baikal has already, been in existence in late Palaeogene. Its origination started
not less than 25-30 millions years ago.
In the prebaikalian period the relief was not nearly so contrasting as at present, yet it was a mountain relief.
Height probably did not exceed 300-500 m above the bottom of the basins, which surrounded these mountains.
Originally the Baikal basin was certainly |
shallower and narrower. Probably it was a river bed, which accepted
waters from uplands of Zabaikalia and Mongolia.
Individual parts of the Baikal basin, which is currently united, were considered by geologists and geographers as
being developed at different times. Some basins subsided more, some less. But this process took place in one and
the same geological period, the Tertiary.
Even in the initial stages of formation, the basins of baikalian type represented beds of more or less large lakes,
connected by rivers, and could constitute a gigantic united system, like the present lakes of the Laurenty system
in North America.
The Baikal became united late in Pliocene - early in Quaternary.
Opinions on mechanisms and history of the Baikal basin formation differ. Investigators of the XVIII century regarded
it to be a sink. Chersky believed that the Baikal basin is a result of slow and progressive transformation of folds
in Laurentian rocks. Then the assumptions of the XVIII century have undergone a change and the Baikal was considered
to be a large graben, and according to Zuss, a combination of two grabens, originally divided by mountains, which
extend from Olkhon island to Svyatoy Nos peninsula.
V.A.Obruchev: "It is deep, wide and its slopes are too steep and abrupt. Such a depression could be formed solely by
disjunctive crustal movements and is comparatively recent in age, otherwise its steep slopes would have been smoothed
out owing to washout, and the lake would have been filled with the slope products".
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Ivanov V.D. believed that the uplift of the land in the form of a wide and flat arch, in which faults and individual
block structures developed in places, was responsible for formation of the recent topography of Pribaikalia and
Transbaikal. The Baikal and the basins resulted from subsidence of high part of the arch. Such basins are known in
geology as the rift basins.
Block tectonics appears to be the main |
mechanism of formation of the topography of the Baikal mountain region. But
geologists are of the opinion that phenomena of earth curve, which form its folding, should be taken into account.
Consequently, curve deformations are also responsible for the formation of the Baikal basin. Pavlovsky E.V.,
Florensov N.A. consider the Baikal basin to be a deep syncline, complicated by normal faults.
GEOLOGICAL & Geophysical Data
Geological age of Lake Baikal:
Pre-rift (pre-baikalian) period (Cretaceous-Late Eocene): 70 - 35 million years
Rift period: 30 - 0 million years
a) protobaikalian (early baikalian) stage (Oligocene - Early Pliocene): 30 - 3.5 million years
b) neobaikalian (proper baikalian) stage (Pliocene - Holocene): 3.5 - 0 million years
The age of deposits on the Baikal shores:
Tompuda River moraine: 39000 years
Rel River moraine: 25580 years +/- 350 years
Chernozems silts on the first baikalian terraces (Holocene optimum) approximately: 7000 years
Peat bogs of Chivirkuy Bay: 10000 - 12000 years
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