Baikalian system of the rifts

BAIKALIAN SYSTEM OF THE RIFTBAIKALIAN SYSTEM OF THE RIFTSS (RU: Байкальская система рифтов) is the system of the grabens of the deep embedment, which are situated on the north-western periphery of the mountainous province of the near-Baikal region. The length is approximately 2000 kilometres. The largest most lowered its parts are the graben depressions: Baikalskaya, Tunkinskaya, Barguzinskaya, Khubsugulskaya. At the north-east and east, this system continues along the direction of the Stanovoy ridge, at the south-west goes away through the Tunkinskaya depression to the Lake Khövsgöl. There is situated within one of these tectonic depressions the most deep continental body of water within the world, namely, the Lake Baikal, with the maximal depth of 1620 metres, which is surrounded by the mountain ridges with the height of up to 2000 metres above its water surface.

The depression of the Lake Baikal distinguishes itself by the asymmetry of the transverse profile with the great steepness of the slopes of the western shores, and more slightly inclined eastern ones; the depth of the crystalline basement is 4500 metres. The grabens within the Baikalian system of the rifts, as the grabens within the other rift zones of the Earth, are associated with the extensive, wide, but clearly linear uplift with the amplitude of up to 3000-4000 metres above the level of the sea. This uplift has got the substantial geomorphologic expression during the Pliocene-Pleistocene time, that is during the epoch of the universal orogeny within the inner Asia. The development of the Baikalian system of the rifts proceeded during the Neogene, sometimes being accompanied by the volcanic activity (now extinct), and continues during the modern epoch, about which there evidences the high seismicity of the given province. The rift structures inherit the position and strike of the earlier, Oligocene - Early Neogene downfolds (Figure). The deep structure of the Baikalian system of the rifts is characterized by the certain de-compaction of the material, and by the rise of the heated basic magma from the upper mantle, which may serve as the cause for the high mobility of the Earth's crust within this region.