LOW VELOCITY LAYERS OF THE CRUST IN NORTH CHINA
华北地区的地壳低速层

Although North China belongs to Craton type in geology,there exist quite a lot of low velocity layers(LVL) in its crust,especially in its eastern region.Most of these LVLs locate at the bottom of the upper crust with depth of 15-25 km.Compared with LVLs in active orogens,the LVLs in North China possess greatly different characteristics.Usually,these LVLs are not large in horizontal scale and are not connected each other.In the same time,the velocity drops are small,usually less than 5%.Considering the therm...