新疆博格达山分段及深浅构造转换关系

The segmentation and the relationship between shallow anddeep structures of Bogda Mountain,Xinjiang, Northwest China

研究表明 ,天山及邻区自中生代以来一直处于热衰减状态 ,博格达山新生代再造山具有“冷隆升”性 ,盆山边界断裂多限于上地壳内 ,而非直通中地壳低速体甚至上地幔的“深大断裂”。造山带内的韧性剪切带是在古生代形成的 ,而不是再造山期的断裂 ,它对造山带隆升及盆山耦合无贡献 ,博格达山的隆升为复式背斜构造所支持。博格达山与准东的关系为背斜北翼与盆地平缓基底构成的挠曲构造 ,而不是被深大断裂分隔的断块。博格达山具有独特鲜明的分段性 ,造山带的两个弧形构造与新生代再生前陆盆地构成独特的“斜方对称”分布样式。以板条观点为指导 ,从盆山单元的平面配置关系和深浅构造转换关系入手 ,探讨了博格达山板内造山阶段的几何学和运动学分段性的成因 。

Study shows that the Tianshan Mountains and its vicinity have undergone thermal attenuation since the Mesozoic; that the re-orogeny in Bogda Mountain in the Cenozoic has the characteristics of cold uplifting; and that most of faults along the boundaries between basin and mountain are limited in the upper crust, and are not the “deep and large faults” which could go downwards to the middle crust or upper mantle. The ductile shear zone in the orogenic belt was formed during the Late Paleozoic and was not the fault formed in the period of re-orogeny, which have nothing to do with the basin-mountain coupling and the uplifting of the mountain; the uplifting of the Bogda Mountain is resulting from the anticlinorium formation of strata. The relationship between the Bogda Mountain and the eastern Junggar basin and Tu-Ha basin is that of a bending structure consisting of one limb of anticline and the basement of basin rather than that of faulted blocks bounded by deep and large faults. The Bogda Mountain shows the characteristics of segmentation horizontally, and of forming of the eastern Junggar Basin to the north of the mountain and Tu-Ha foreland basins to the south, which leading to the formation of the special tectonic style of rhombic symmetry.Directed by the slab tectonics and based on the study of the relationship between deep and shallow structures and horizontal relationship between basin and mountain, the authors discuss the kinematical and geometrical segmentation of the Bogda Mountain during the intraplate orogeny and establish the basin-mountain coupling model of this region.