The Crustal Structure of Western Shandong and the High‐Velocity Body in the Crust

Abstract The crustal velocity structure of western Shandong is revealed by a 320 km long DSS profile from Liaocheng to Lianyungang. In this area, the upper crust has a two‐layer structure with a total thickness of 18~20 km and a velocity of 5.4~6.2 km/s; the lower crust is also divided into two layers with a total thickness of 13~15 km and a velocity of 6.4~6.7 km/s. The depth of Moho is from 33 km to 35 km. The Pn velocity in this region is 7.9 km/s. The velocity in the crust varies considerably laterally. The average velocity is from 6.2 km/s to 6.5 km/s, which is slightly higher than the normal value. In the crust there are two nearly upright high‐velocity blocks, extending from the lower crust to the upper crust till the bottom of the sedimentary basin. It is possible that a large amount of magma from the upper mantle rose up into the crust, making the local average velocity higher. The high velocity blocks are probably the channels of magma uprising. The study on the crustal structure of western Shandong is of certain significance for investigating the mechanism of disintegration and subsidence of ancient platform.