摘要
位于中国西北部的天山造山带与准噶尔盆地是典型的盆岭构造。通过对横跨天山造山带与准噶尔盆地的沙雅-布尔津地学断面地震宽角反射、折射资料进行小波分析，获得了天山造山带与准噶尔盆地壳-幔过渡带的详细结构。结果表明，天山造山带的壳-幔间是以多个薄层过渡的。这些薄层的层厚度2～3km不等，层速度高低相间，总厚度约20km，平均速度较低，接近塔里木盆地下地壳的速度。塔里木盆地北缘与准噶尔盆地的壳-幔间不具有这种特点，其壳-幔间主要表现为一级间断面。而位于中国东北部的间阳-海城-东沟深地震测深剖面所揭示的辽东台隆-辽河盆地-燕山台褶带壳-幔过渡带的结构似乎具有完全相反的特征：辽河盆地的壳-幔过渡带比较复杂，它由数个薄层叠合而成，总厚度达15km；辽东台隆与燕山台褶带壳-幔过渡带结构十分简单，皆以一级间断面过渡为主。研究认为，造成二者差异的主要原因是它们所处的构造环境不同：前者为挤压环境，而后者为伸展环境。在挤压环境下，复杂的壳-幔过渡带形成于造山带的下面；而在伸展环境下，复杂的壳-幔过渡带形成于盆地的下面。壳-幔过渡的复杂程度与构造活动性相联系，在一定程度上反映了岩石圈目前的构造活动水平。
Located in the northwestern China, the Tianshan orogenic belt and Junggar Basin isa magnificent range and basin structure. By wavelet transform of seismic wide angle refiection/refraction data obtained from the geoscience transect from Shaya, passing through the Tianshanorogenic belt and Junggar Basin, to Burjing, the authors obtained the detailed structure of thecrust-mantle transitional zone of this basin and rangr structure. The results show that thecrust-manle transitional ane of the Tianshan orogenic belt is composed of 7~8 thin layerswhich are 2 or 3 km in thickness and alternatively high and low in velocty. The total thicknessof the crust-mantle transitional are of the Tianshan orogenic belt is about 2o km, and the av-erage velocity of this zone is relatively low, which is similar to that of the lower crust of thenorthern margin of the Tarim Basin. However, these similar features have not been found inthe crust-mantle transitional are of the Junggar Basin. In the Junggar Basin, the crust-mantletransitional zone is mainly composed of one single interface. While as revealed by the LuyangHaicheng-Donggou DSS profile located in northeastern China, the structural characteristics ofthe crust-mantle transitional zone of the Liaodong platform uplift-Liaohe Basin-Yanshan plat-form fold belt are totally different from those in the Tianshan orogenic belt and Junggar Basin.In the Liaohe Basin, the crust-mantle transitional zone is comparatively complex, which iscomposed of several layers with a total thickness of 15 km. While the crust-mantle structures inthe Liaodong platform uplift and Yanshan platform fold belt are rather simple, which are main-ly composed of one single interface. The research indicates that the different tectonic environ-ments are responsible for the different structural features of the crust-mantle transitional zone.The former is in a compressional environment and the latter, extensional one. In a compressedsetting, the complex crust-mantle transitional ane may develop under an orogenic belt while inan extensional setting it may develop under a basin. The structural characteristics of the crust-mantle transitional zone are related to tectonic activities and may present, to some extent, thedegree of tectonic activities of the lithosphere at present.
出处
《地学前缘》
EI
CAS
CSCD
1999年第3期165-172,共8页
Earth Science Frontiers
关键词
天山造山带
盆岭构造
壳-幔过渡带
辽东台隆
Tianshan orogenic belt, basin and range structure, crust-mantle transitional zone,Liaodong platform uplift, Liaohe Basin, Yanshan platform fold belt
