Three layers are present in the middle and upper crusts in the northern border of Sulu orogenic belt, as revealed by the S-N-strike reflecting seismic profiles that cross the Zhucheng sag.

• 横穿诸城凹陷的南北向反射地震剖面揭示,苏鲁造山带北侧边界的中上地壳中存在着三层结构,即上部的胶莱盆地沉积盖层、中部的苏鲁楔状地体和下部代表华北板块的胶北地体;