【摘要】 西昆仑构造带及其邻区的宽频带地震探测和航磁异常研究结果表明,西昆仑构造带的南部(亦即青藏板块)的岩石圈向塔里木盆地下部俯冲,西昆仑的蛇绿岩带是闭合于加里东造山时期的古特提斯洋的残迹;青藏板块在向塔里木盆地俯冲的过程中,受到来自北部坚硬、古老的塔里木地体的强力阻挡,使得向北俯冲的岩石圈产生裂解,发生拆沉;在青藏板块岩石圈发生拆沉作用的同时,南部青藏板块岩石圈的回弹及软流层的浮力作用导致上部地壳发生引张断陷,深部熔岩上涌造成了碱质型熔岩沿断陷裂隙喷溢,同时也形成了构造带两侧反逆冲构造格局;西昆仑中央断裂是青藏高原的“第四缝合带”,北昆仑构造带仅仅是由于在青藏板块岩石圈发生拆沉作用时,西昆仑构造带中地壳浅部物质逆冲于塔里木前陆之上形成的。更多还原

【Abstract】 The broadband seismic survey and aeromagnetic anomaly study show that the lithosphere below the southern part (i.e. Qinghai-Tibet plate) of the West Kunlun tectonic belt was subducted beneath the Tarim basin and that the ophiolite belt of the West Kunlun is the relics of the Paleo-Tethys ocean that closed during the Caledonian orogen. Due to the strong resistance from the rigid old Tarim terrane during the subduction of the Qinghai-Tibet plate, the north-subducting lithosphere broke up and delaminated. Meanwhile, the rebound of the Qinghai-Tibet lithosphere and buoyancy of the asthenosphere caused extensional downfaulting of the upper crust, which allowed the molten magma at depth to upwell, thus resulting in eruption of alkaline magma along the faults. Furthermore, this also formed an antithetic thrust tectonic framework on both sides of the tectonic belt. The West Kunlun Central fault is actually the "fourth suture" of the Qinghai-Tibet Plateau, whereas the North Kunlun tectonic belt just formed by thrusting of the material at the shallow crustal level in the West tectonic belt over the Tarim foreland during delamination of the lithosphere of the Qinghai-Tibet plate.更多还原