PALEOZOIC COLLISIONAL TECTONICS AND MAGMATISM OF THE CHINESE TIEN-SHAN, CENTRAL-ASIA
PALEOZOIC COLLISIONAL TECTONICS AND MAGMATISM OF THE CHINESE TIEN-SHAN, CENTRAL-ASIA
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DOI：
10.1016/0040-1951(93)90225-9
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发表时间：
1993-04-15
期刊：
影响因子：
2.9
通讯作者：
CHI, Z
中科院分区：
文献类型：
--
作者：
ALLEN, MB;WINDLEY, BF;CHI, Z
中国天山山脉是一个包含两个碰撞带的古生代造山带。较老的南部碰撞使塔里木地块北侧的一个朝北被动大陆边缘增生为一个细长大陆带南侧的活动大陆边缘，即中央天山。碰撞发生在秦布拉克-夸瓦布鲁克断裂带（南天山缝合线）。碰撞的时间很难确定，但可能在晚泥盆世-早石炭世。由于塔里木地块北侧此时发生了一次大的不整合，并且油树沟蛇绿岩与中泥盆世的沉积物叠瓦状，因此我们提出了这一时代。一个更年轻的，可能是晚石炭世-早二叠世沿北天山断裂（北天山缝合线）的碰撞使中天山的北侧形成了一个岛弧，位于其北部，即北天山弧。这次碰撞被中石炭世弧岩浆活动的终止和在灭弧上发育的前陆盆地中出现的晚石炭世或早二叠世碎屑所包围。碰撞产生的逆冲片岩被认为是造成盆地沉降的构造荷载。碰撞后，古生代沿北缝合带发生右旋剪切，并伴有中天山基性和酸性岩浆的侵入。天山三个岩石圈块体的晚古生代基性火成岩，尽管有多次后期的一次或两次碰撞，但均具有与超俯冲带环境有关的化学特征。每个地块的岩石也具有不同的微量元素化学特征，支持了造山带的三次构造划分。目前尚不清楚这些化学差异是否代表了不同的震源特征，或者是由于不同时期的岩浆活动与后来的右旋走滑断层运动并在一起。由于天山的南部碰撞带是两个碰撞带中较老的一个，因此严格意义上说，塔里木地块不是与欧亚大陆块体碰撞，而是与一个大陆块体碰撞，而这个大陆块本身与欧亚大陆至少隔着一个海洋。在晚石炭世-早二叠纪时期，这片海洋的毁灭代表了中亚这一地区所有海洋盆地的最终消失。
The Chinese Tien Shan range is a Palaeozoic orogenic belt which contains two collision zones. The older, southern collision accreted a north-facing passive continental margin on the north side of the Tarim Block to an active continental margin on the south side of an elongate continental tract, the Central Tien Shan. Collision occurred along the Qinbulak-Qawabulak Fault (Southern Tien Shan suture). The time of the collision is poorly constrained, but was probably in in the Late Devonian-Early Carboniferous. We propose this age because of a major disconformity at this time along the north side of the Tarim Block, and because the Youshugou ophiolite is imbricated with Middle Devonian sediments. A younger, probably Late Carboniferous-Early Permian collision along the North Tien Shan Fault (Northern Tien Shan suture) accreted the northern side of the Central Tien Shan to an island arc which lay to its north, the North Tien Shan arc. This collision is bracketed by the Middle Carboniferous termination of arc magmatism and the appearance of Late Carboniferous or Early Permian clastics in a foreland basin developed over the extinct arc. Thrust sheets generated by the collision are proposed as the tectonic load responsible for the subsidence of this basin. Post-collisional, but Palaeozoic, dextral shear occurred along the northern suture zone, this was accompanied by the intrusion of basic and acidic magmas in the Central Tien Shan. Late Palaeozoic basic igneous rocks from all three lithospheric blocks represented in the Tien Shan possess chemical characteristics associated with generation in supra-subduction zone environments, even though many post-date one or both collisions. Rocks from each block also possess distinctive trace element chemistries, which supports the three-fold structural division of the orogenic belt. It is unclear whether the chemical differences represent different source characteristics, or are due to different episodes of magmatism being juxtaposed by later dextral strike-slip fault motions. Because the southern collision zone in the Tien Shan is the older of the two, the Tarim Block sensu stricto collided not with the Eurasian landmass, but with a continental block which was itself separated from Eurasia by at least one ocean. The destruction of this ocean in Late Carboniferous-Early Permian times represented the final elimination of all oceanic basins from this part of central Asia.