Exploration and Study of Deep Crustal Structure in the Quanzhou Basin and Its Adjacent Area

摘要

The Quanzhou basin and its adjacent areas locate in the middle of the southeastern coast seismic belt on the Chinese mainland. The very fine geometry structure of this area from near ground to Moho interface and the relationship between the deep and shallow faults are obtained based on deep seismic reflection profiling. This profile is the first deep seismic reflection profile in this area and it indicates that the crust can be divided into the upper crust and the lower crust and the thickness of crust is from 29.5 km to 31 km in this area. The upper crust and the lower crust can be also divided into two layers. There are shallow normal faults developed in the upper crust and extending to the depth from 6 km to 12 km. The angle of those listric faults decreases with depth and the faults joint into the C_1 interface (detachment surface). There is a high angle fault under the Yong'an-Jinjiang fault belt which cuts off the interface of the upper crust and the lower crust and the Moho interface. Although there is no connection between the shallow and the deep faults, it offers deep structural environment for moderate and strong earthquake because of the deep high angle fault. This exploration result improves the reliability and precision of explanation of deep crustal structure in this area. The pull-apart and listric normal fault model indicates that the upper crust structure accords to the dynamic process of Taiwan Straits. This is helpful for seismicity estimation of Quanzhou and its adjacent area and important for obtaining more of the dynamic process of the southeast coast seismic belt.