华北不同构造块体地壳结构及其对比研究

Crustal structure and comparison of different tectonic blocks in North China

华北古大陆块体经多期构造运动的改造使地壳构造具有明显的分块特征.利用华北地区近30条、共约两万公里的深地震测深资料及成果,进一步研究华北各次级块体内部地壳细结构,对比分析各块体的结构差异.根据不同的地壳结构特征,华北地壳可分为三大类:西部鄂尔多斯盆地地壳结构简单,基底结构完整,为稳定古大陆地壳;华北中部隆起区太行山及北部阴山、燕山隆起区地壳结构相对简单,中部地壳和下地壳局部区域轻微速度逆转,可能与该区域地壳增厚隆升的壳内介质解耦形变有关;华北东部裂陷盆地地壳结构复杂,基底下陷、破碎,壳内介质松散、速度低,Moho上隆、地壳减薄,横向结构差异明显,显示了新生地壳构造特征.在此基础上,综合研究、探讨了华北地壳分块构造以及与之相关的动力学演化.

North China paleocontinental block underwent reconstruction through multi-stage tectonic movements, and the crustal structure in sub-blocks has distinct characteristics. Based on data and results of nearly 30 deep seismic sounding profiles with a total length of about 20000 km, the fine structures of the crust within each sub-block are further studied in North China, structural differences among the blocks are compared. On the basis of different tectonic features, the crust in North China may be divided into 3 classes: a simple crustal structure in Ordos basin in the western part of the region, with an integrated basement structure, showing the crustal structure feature of stable paleocontinent; a relatively simple crustal structure in Taihangshan mountain uplifts located in the middle part of North China, and Yinshan mountain and Yanshan mountain uplifts located in the northern part of North China, where the slight velocity reversal in local areas of middle and lower crusts is possibly related to medium decoupling deformation within the crust caused by the regional crustal thickening and uplifting; a complex crustal structure in the rift-depression basin in the eastern part of North China, with a sinking and fragmentized basement, loosen medium within the crust, low velocity, uplifted Moho and thinned crust, lateral tectonic differences obvious, showing tectonic features of the rebirth crust. Furthermore, crustal sub-block tectonics and related dynamic evolution in North China are comprehensively studied.