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ORIGIN AND EVOUTION OF TECTONICS IN CENTRAL ASIA
- Shi Yangshen, Lu Huafu, Jia Dong, Chen Churning, Cai Dongsheng, Wu Shiming
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1996, 2(2):
134-145.
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Centrl Asia is a complex terrane col1age tectonics rather than neither an unified pre-Cambrian continent, nor an unified southwestward growing Paleozoic fold belt. The Tarim plate, Siberian plate and Kazakhstan plate are the basic framework of Cenlra1 Asis tectonics. The Irtysh suture zone as the southwest boundary of the Siberian plate and the South Tianshan suture zone as the northern boundary of the Tarim plate confine the Kazakhstan plate in northeastern and southern borders respectively. The Kazakhstan plate is divided into mnay terranes as shown in Figure 1 and Table 1, including Yili-Muyimkum-Kokchetav and Atasu-Mointy microcontinent, Bmkash- Junggar oceanic crust terrane, and the island arc of Zharma-Saur terrane, Chingiz terrane, Tianjiz-Alakol terrane, Sarytum terrane, and Syr River terrane. During the Ordovician the Atasu-Mointy terrane, Sarytum terrane, Yiii-Muyumkum-Kokchetav terrane and Syr River terrane (terranes 4, 14, 3, 15 in Fig.2a) originally formed a roughly north south trending island arc, the Atasu-Sarytum-Yili-Syrary (ASYS) arc. To the east of ASYS arc the paleo-ocean composed of the South Tianshan terrane and Balkhash-Junggar terrane (terranes 9, 7 in Fig.2a) is named the South Tianshan-Balkash-Junggar ocean (SBAJUN ocean), which subducted westward beneath the ASYS arc. The paleo-island are and ocean margin formed a Early Paleozoic trench are system, the SBAJUN-ASYS trench are system. In fact the SBAJUN ocean was the oceanic crust to the north part of the Tarim plate. The SBAJUN-ASYS trench arc system recorded the subduction process of the Tarim plate to the ASYS island arc. During the same period, to the north
of SP~AJUN ASYS trench—arc system , there was the east-northeast trending Irtysh Chingtien trenth-arc system The Chingtien are simplified from Zharma-Chingiz, riangiz arc is composed of the Zharmar-Saur terrane. Chingiz terrane and Tiangiz-Alako]terrane(terranes11, 12, 13 in Fig2a). while the Irtysh ocean composed of the Irtysh-Kelamaili terrane (terrane 8 ln Fig 2a)subdueted southeastward beneath the Chingtien arc. forming the lrtysh Chingtien trenth-arc system and northwestward beneath the Ahai terrane and Ruding Altai terran (terranes 20, 10 in Fig. 2a) During the Devonian the northwestward migrating continental crust of the Tarim craton collided against the ASYS arc obliquely. resulting in that the latter was broken into four pieces i. e. the Atasu-Mointy terrane. Sarytum terrane Yili Muyumkum Kokchetav terrane and Syr River terrane. Between them large sinistral strike slip faulting took place. At the same time, the SBAJUN ocean was seperated into South Tianshan ocean and Balkash-Junggar ocean, while the Irtysh ocean lithosphere continued its northwestward and southeastward subduction During the Carboniferous. the dextral strike-slip faulting along the northern boundary fault and the sinistral strike slip faulting along the southern boundary fault, the Batkhash-Junggar terrane and Tingiz-Alakol terrane exhibited a westward convex orocline and the Balkhash-Junggar ocean and Irtysh ocean subducted north and south, and finally they were all consumed, the complex terrane collage tectionic in central. Asia was essentially formed. Therefore the central Asia continent is in regrated
from the collage of the different terranes in the archipelago through consuming the oceanic crust. The large scale thrusting and strike-slip faulting played same important role in the processes of the formation of collage tectonics.
