Investigation of igneous rocks in Huanghua depression, North China, from magnetic derivative methods

Abstract

The igneous rock study plays an important role in understanding the tectonic evolution of sedimentary basins. The distribution of igneous rocks is one of the basic aspects in the igneous rock study. Based on the magnetic susceptibility contrast of igneous and other rocks, magnetic methods are usually used in the igneous rock investigation. In this paper, we delineated the distribution of igneous rocks in Huanghua depression based on the reduction to pole (RTP) magnetic anomaly and its derivative processing results. The main methods used to enhance the anomaly character of igneous rocks include total horizontal derivative, analytic signal modules and the tilt angle. Based on the RTP anomaly and the derivative results, three types of igneous rock distribution areas are predicted in Huanghua depression. The large scale igneous rocks are mainly distributed in the north part of Huanghua depression. The string bead-shaped igneous rocks are mainly located in the north and southwest parts. Some craters are located in the middle-south part. The distribution of igneous rocks is controlled by the deep buried fault along the coastal boundary and the associated tertiary faults. Our study verified the validity of the magnetic derivative methods for the planar distribution study of igneous rocks. The study results of Huanghua depression are the basis of the seismic interpretation of igneous rocks and the tectonic study in this area. © 2011 Nanjing Geophysical Research Institute.