Please put an active hyperlink to our site (www.rusnature.info) when you copy the materials from this page

Biomes and Regions of Northern Eurasia

The Far East

<<< Introduction | Biomes & Regions Index | Climate >>>

Tectonics and Endogenic Processes

From the tectonic point of view, the Far East has the following characteristics:

• 1. It is positioned between the continental and the oceanic plates.
• 2. A mosaic structure of the Earth's crust.
• 3. The contemporary endogenic processes (seismic activity and volcanism) are of high intensity.
• 4. Strong geomorphical contrasts: close proximity of deep oceanic depressions and high mountains.
• 5. Complex coastline.

The main factor determining the dynamics of the Pacific tectonic belt is the subduction of the oceanic plates under the Asian continent (Zonenshain et al., 1990; Tektonosfera, 1992). There are two tectonic belts within the Pacific rim: the Sikhote-Alin-Sakhalin belt, which encompasses the Sikhote-Alin mountains and the island of Sakhalin and has mainly a Mesozoic history, and the Koryak-Kamchatka belt, which includes structures positioned between the Okhotsk-Chukotka volcanic belt and the Pacific Ocean (i.e., the Kamchatka peninsula and the Kuril islands). The subduction of the Pacific Plate at a rate of approximately 10 cm a^-1 results in the active contemporary tectonics of the Koryak-Kamchatka belt. At present, 313 terrestrial and 105 submarine volcanoes of different ages exist in the region. Of those, 62 are active, which makes the Russian Far East the major centre of volcanic activity outside Java (Sergeev and Krasny, 1987). This is a perfect example of accretional tectonics which includes a number of volcanic belts of various ages corresponding to ancient island arcs. The movement of the arcs was controlled by the position of subduction zones and of alien blocks (exotic terrains) which has resulted in the contemporary mosaic tectonics of the region. Tectonics and geology are discussed in greater detail in the regional sections of this chapter.

<<< Introduction | Biomes & Regions Index | Climate >>>