论文部分内容阅读
拜城-大柴旦人工地震宽角反射/折射剖面穿过了塔里木盆地北缘的库车坳陷和塔北隆起两个构造单元.利用该剖面上的拜城、库车、轮台和库尔勒4个爆炸点的地震资料,通过二维横向非均匀介质条件下的射线追踪与理论地震图计算,获得了塔里木盆地北缘地壳与上地幔顶部的二维速度结构与构造.结果表明,库车坳陷与塔北隆起的地壳分层具有统一性,但界面深度、地壳厚度以及速度分布沿剖面变化明显,其中地壳厚度的变化主要体现在中地壳与下地壳.在库车坳陷的拜城以及塔北隆起的轮台爆炸点附近莫霍面抬升,使地壳分别减薄为42和47km.地壳最厚处是库车坳陷与塔北隆起的转换部位,地壳厚度达52km.此处的上、下地壳内分别发育壳内速度异常体,其中上地壳表现为高速异常,下地壳发育低速异常体,它们几乎分布在同一垂线上,相应位置的盖层较厚.根据地壳的速度结构与构造,可将剖面划分为库车坳陷、塔北隆起和两者之间的过渡带3个部分,每一部分都有自己独特的速度变化特点、基底结构形式和深浅部构造关系.塔里木盆地北缘地壳与上地幔顶部速度结构与构造在东西向的差异可能意味着塔里木盆地向天山造山带俯冲消减的速度和强度的不同,引起天山造山带的构造分段.
The Baicheng-Dachaidan seismic wide-angle reflectivity / refraction profile passes through two structural units, the Kuqa Depression and the Tabei Uplift in the northern margin of the Tarim Basin. Using the results of the study on the Baicheng, Kuche, Luotai and Korla 4 And explored the two-dimensional velocity structure of the crust and the upper mantle in the northern margin of the Tarim Basin through the ray tracing and theoretical seismogram calculation under two-dimensional transverse inhomogeneous media.The results show that the Kuqa depression The crust and the Tabei uplift have a uniform crustal stratification, but the interface depth, crustal thickness and velocity distribution have obvious changes along the section, in which the crustal thickness changes are mainly reflected in the middle crust and the lower crust. The uplift of the Moho near the turbulence of the Tabei uplift made the crust thinning down to 42 and 47 km, respectively. The thickest part of the crust is the conversion part between the Kuqa depression and Tabei uplift, with a crustal thickness of 52 km , The inner crustal velocity anomalies are developed in the lower crust, of which the upper crust is characterized by high-speed anomalies and the lower crust is characterized by low-velocity anomalies, which are distributed on the same vertical line and have thicker caprock at corresponding positions. According to the crustal velocity Structure and structure, the section can be divided into three parts: Kuche depression, Tabei uplift and transition zone between the two, each with its own unique characteristics of velocity variation, the structure of the basement structure and the relationship between depth and thickness. The east-west differences in the velocity structures and tectonics at the top of the northern margin of the basin and the upper mantle may suggest that the velocity and intensity of the subduction of the Tadam orogenic belt from the Tarim Basin are different and cause the tectonic segmentation of the Tianshan orogenic belt.