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利用超长观测距地震宽角反射/折射剖面探测技术,获得了近东西向横穿华北克拉通不同块体的反映地壳-上地幔岩石圈结构的不同深度、不同属性地震波震相特征数据.通过对各个块体内的地震波震相特征对比分析研究,除识别出地壳内常规的Pg波、Pci波、Pm P波和Pn波外,还清楚的对比出了岩石圈尺度的两组震相PL1和PL2波.经过一维、二维地震走时及波形拟合,获得了沿剖面长约1500 km的不同块体的壳幔二维速度结构与构造特征.结果表明:沿剖面地壳及岩石圈自东向西加厚趋势的明显,但各组地震波反、折射界面在各个块体内又显示出局部变化明显等特征.结晶基底在各个块体内变化较大,在华北凹陷盆地内最深达到7.8 km,在胶东半岛及太行吕梁地块较浅约2.0 km;莫霍界面形态整体显示出东浅西深,在鄂尔多斯块体内最深达到46 km,而在华北断陷盆地内显示隆起特征;L1界面仅在太行山以西区域显示,深度约为80 km,变化较缓.岩石圈L2界面东浅西深在75~160 km范围内变化,在太行山以西有一急剧加深趋势,形成一个陡变带.
By using the ultra-long observation seismic wide-angle reflection / refraction profile detection technology, the seismic data of different depths and attributes with lithosphere-crust lithosphere structure of different crustal-upper mantle lithospheric transversions across different blocks of North China Craton are obtained. Through the comparative analysis of the seismic phase characteristics in each block, in addition to identifying the regular Pg wave, Pci wave, Pm P wave and Pn wave in the crust, two sets of seismic phases PL1 And PL2 waves.The structure and tectonic features of two-dimensional crust and mantle beneath different blocks with a length of about 1,500 km are obtained through the fitting of one-dimensional and two-dimensional seismic traveltimes and waveforms.The results show that the crust and lithosphere The trend of thickening in the east to the west is obvious, but the anti-refraction interface of each group of seismic waves shows the obvious local variation in each block.The crystalline basement varies greatly in each block, the deepest in the North China depression basin is 7.8 km, In the Jiaodong Peninsula and Taihang Lvliang block, the shallow is about 2.0 km. The Moho interface shows an east-west and deep-west part, the deepest reaches 46 km in the Ordos block and uplift features in the North China rift basin. The L1 boundary The surface only shows westward to the Taihang Mountains with a depth of about 80 km, with a gradual change.The east-west depth of the L2 boundary of the lithosphere varies from 75 to 160 km, with a sharp deepening trend to the west of the Taihang Mountains, forming a steep zone.