塔里木盆地西北缘与南天山早-中二叠世盆山耦合特征

Early-Middle Permian basin-mountain coupling features between northwestern margin of the Tarim basin and the South Tianshan orogen

通过对塔里木盆地西北缘及相邻南天山造山带的早-中二叠世岩相古地理、构造和岩浆作用的分析表明,塔里木盆地西北缘在早-中二叠世由于地幔柱作用而导致玄武质岩浆活动,南天山造山带内部则发育几乎同时代的碰撞后花岗岩。盆山结合部位早-中二叠世的沉积中心处于不断沉降的状态,而且沉积中心逐渐向塔里木地块之上迁移。南天山在早-中二叠世碰撞后伸展背景下的隆升作用导致塔里木岩石圈向南天山之下发生陆内俯冲作用,在山前形成类似周缘前陆盆地的构造环境,山前沉积中心相当于周缘前陆盆地系统的前渊相带。塔里木盆地内部早二叠世的地幔柱活动与南天山的碰撞后伸展作用没有明显的相关关系,但是南天山在早-中二叠世的碰撞后伸展作用则与塔里木盆地西北缘的沉积-构造作用具有良好耦合关系。

Analysis of Early-Middle Permian lithofacies-paleogeography, structure and magmatism in the northwestern margin of the Tarim basin and adjacent South Tianshan orogen shows that basaltic magmatisms in the northwestern margin of the Tarim result from the mantle plumes, while the contemporaneous post-collisional granites develop within the South Tianshan orogen. The Early-Middle Permian depocenters in the intermediate zone between Tarim and the South Tianshan orogen are characterized by stable depression, and the depocenters migrates gradually toward the Tarim block. Early-Middle Permian uplifting of the South Tianshan orogen because of the post-collisional extension results in intracontinental subduction of the Tarim lithosphere under the South Tianshan lithosphere, and structural surroundings which is similar to the peripheral foreland basin arises in the intermediate zone. The depocenters correspond to the foredeep of the peripheral foreland basin system. There is no clear interrelation between the Early-Middle Permian mantle plumes within the Tarim and the post-collisional extension, but the post-collisional extension of the South Tianshan orogen of Early-Middle Permian shows good coupling features with sedimentation-structure in the northwestern margin of the basin Tarim.