张渤构造带中东段二维P波速度结构——安新—香河—宽城剖面

2-D P-WAVE VELOCITY STRUCTURE IN THE MIDEAST SEGMENT OF ZHANGJIAKOU-BOHAI TECTONIC ZONE: ANXIN-XIANGHE-KUANCHENG DSS PROFILE

为了获取首都圈地区 (3 8.5°N～ 41 .0°N ,1 1 4.0°E～ 1 2 0 .0°E)三维地壳精细结构 ,在该地区实施了 6次人工爆破 ,进行三维深地震测深 .利用纵测线安新三台、安次旧州、三河新集、遵化平安城 4炮的人工爆破资料 ,研究张渤带中东段的二维速度结构 .华北平原和燕山褶断带的深部分界位置大体在宝坻断裂一带 ,深部结构构造表现为宽约数十千米的一个异常带 .分界处的壳幔结构为 :结晶基底明显凹陷 ;壳幔边界之上为强正速度梯度层 ,厚约 3～ 4km ,可能是上地幔物质上涌到下地壳底部的结果 ;壳内界面和莫霍边界上隆 ,并可能存在错断 .华北盆地地壳薄 ,壳内存在低速体和局部结构异常 ;燕山褶断带地壳厚 ,壳内分层明显 ,速度分布均匀 .两构造单元结构存在明显差异 .

In order to get the 3-D fine velocity structure in the Capital-circle area of China, 6 explosions, ranging from 1800 to 2500 kg, were conducted and recorded by an array of 240 seismographs. A reflection/refraction survey was carried out along the profile extending from Anxin county, Hebei Province northeastward to Yanshan Mountains, crossing the Zhangjiakou-Bohai tectonic zone. The 2-D velocity structure of P wave was imaging along the profile. The results show that abnormality exists in the deep structure ...