塔里木盆地中部地震转换波测深及其解释
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摘要
沿塔里木盆地中部的库车—塔中—塔南测线，首次进行了地震转换波测深。探测结果表明，本区岩石圈具有明显的层状－块体结构，地壳厚度４０～５０ｋｍ，隆起区约为４０ｋｍ，凹陷区约为５０ｋｍ。上地壳的厚度在盆地中部明显减薄，中地壳波速相对偏高（ＶＰ＝６．４～６．５ｋｍ／ｓ），下地壳上部普遍存在低速薄层，结晶地壳的速度高于周围青藏高原和天山地区的波速，波速结构表明地壳具有陆壳性质，地壳内存在具有逆冲性质的深部断裂。综合解释认为，自新生代以来，在印度－欧亚板块边界的强大挤压力作用下，岩石圈内包括结晶基底面和莫霍面在内的各深部界面（岩层）的准同步挠曲变形和地壳刚性块体沿深部逆冲断裂的调整运动，是塔里木盆地岩石圈中主要的深部动力学过程。
A deep sounding survey by the method of converted waves of earthquakes has been completed along the Kuche Tazhong Tanan profile in the central part of the Tarim Basin. The lithosphere of study region is characterized by the layered blocked structures with the crustal thickness about 40～50km. The crustal thickness is about 40km in the uplifted region and it is about 50km in the subsided region. The upper crust (the granitic gneiss layer) is obviosely thinning to the central part of the Tarim Basin. The velocity of the middle crust is relatively high( V P= 6.4 ～6.5km/s, V S=3.4～3.5km/s). There are some thin low velocity layers in the upper part of the lower crust. The average velocity of the crystalline crust of the Tarim basin is higher than the surrounding Qing Zhang plateau and Tianshan mountain regions. The velocity structures of the basin show its continental crust character. All the data of the investigation show that since the Cenozoic Era under the action of strong compression force from the India plate,the quasi synchronous bend deformation of all lithospheric layers and the adjusted movement of the rigid crust blocks along the deep sited faults may be the main deep dynamic processes in the lithosphere of the Tarim basin.
A deep sounding survey by the method of converted waves of earthquakes has been completed along the Kuche Tazhong Tanan profile in the central part of the Tarim Basin. The lithosphere of study region is characterized by the layered blocked structures with the crustal thickness about 40～50km. The crustal thickness is about 40km in the uplifted region and it is about 50km in the subsided region. The upper crust (the granitic gneiss layer) is obviosely thinning to the central part of the Tarim Basin. The velocity of the middle crust is relatively high( V P= 6.4 ～6.5km/s, V S=3.4～3.5km/s). There are some thin low velocity layers in the upper part of the lower crust. The average velocity of the crystalline crust of the Tarim basin is higher than the surrounding Qing Zhang plateau and Tianshan mountain regions. The velocity structures of the basin show its continental crust character. All the data of the investigation show that since the Cenozoic Era under the action of strong compression force from the India plate,the quasi synchronous bend deformation of all lithospheric layers and the adjusted movement of the rigid crust blocks along the deep sited faults may be the main deep dynamic processes in the lithosphere of the Tarim basin.
引文
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