塔北隆起—库车坳陷区中新生代基底-盖层构造变形机理

Structural deformation mechanism of the Meso-Cenozoic basementand cover in the north Tarim uplift-Kuqa depression

利用三维建模软件获取了塔北隆起—库车坳陷区现今及不同时期基底构造格局,为基底构造分析提供了新的技术方法。研究表明,三叠纪—古近纪,塔里木盆地北部块体的基底构造基本处于稳定状态,基底-盖层构造变形不明显;新近纪,克拉苏背斜带以北的塔里木盆地基底明显向天山倾斜,库车基底俯冲变形导致基底转折带逐渐向南迁移,库车前陆盆地形成;第四纪时期,库车-拜城盆地的基底整体向天山下倾斜,基底构造的强转折带迁移到塔北隆起带;新近纪以来库车坳陷的基底转折期与塔北隆起盖层的负反转构造形成期在时间上一致,在空间上,库车坳陷的基底在强烈沉降俯冲的同时,相邻塔北隆起的基底相对隆起,形成库车新生代前陆盆地的前隆;库车前陆冲断带的形成是在库车基底斜坡上伴随天山的推覆而形成的;塔北隆起为库车前陆盆地的前隆,基底俯冲变形及其转折带迁移导致塔北隆起盖层负反转构造的形成。

The 3D modeling software provides a new method for the analysis of the basement structures. The present basement structural framework and the basement structural framework in different periods in the north Tarim uplift-Kuqa depression were constructed using this modeling software. The results show the following: in the Triassic-Paleogene, the basement structure of the northern block of the Tarim basin is essentially in a stable state and the structural deformation of the basement and cover were not pronounced; in the Neogene, the basement of the Tarim basin north of the Kalasu anticline was obviously inclined toward the Tianshan Mountains and the subduction-deformation of the Kuqa basement resulted in gradual southward migration of the kink belt and the formation of the Kuqa foreland basin; in the Quaternary, the basement of the Kuqa-Baicheng depression plunged en bloc beneath the Tianshan Mountains and the kink belt of basement migrated to the north Tarim uplift. In terms of time, the main stage of subduction and kink belt formation of the basement of the Kuqa depression since the Neogene coincides with the stage of development of negative inversion structures in the sedimentary cover of the north Tarim uplift, and in terms of space, simultaneously with the strong subsidence and subduction of the basement of the Kuqa basin, the basement of the north Tarim uplift was uplifted, forming the forebulge of the Cenozoic Kuqa foreland basin. The Kuqa foreland thrust zone formed on the slope of the Kuqa basement concomitantly with overthrusting of the Tianshan in the Quaternary. The north Tarim uplift is the forebulge of the Kuqa foreland basin. The subduction-deformation and kink belt migration of the Kuqa basement resulted in the development of the negative inversion structure in the sedimentary cover of the north Tarim uplift.