Abstract:

Ruyuan-Chaozhou MT profile was measured to study the struture of deep lithosphere, deep faults and granite distribution laws in northern Guangdong.Basing on the electrical structure from the 2D inversion, the authors study the conductivity properties of the lithosphere in northern Guangdong, find that there are three granite along the distribution profile, showing different types, and may represent different genetic model. There are three faults along the profile: between the Ji’an-Sihui fault and Ganjiang fault in Shaoguan east have a deep low resistivity fracture zone with the depth of 20 km, froming a fault basin; Crust-mantle mixing type granite and crust-mantle high conductivity layer develop along the two sides of Heyuan-Shaowu fault, have compplicated electrical structures in deep lithoshpere, this area maybe the place of  dramatic action between crust and mantle;Lishui-Haifeng fault controls the distribution of granite from Late Yanshan period. In the depth of 50-150 km between the Shaoguan-Lianping and the Longchuan-Fengshun, two huge anomolies with low resistivity develop that maybe the “channel” formed in the underplating of mantle substances, and the direction of the underplating points to the area between Lianping and Longchuan, due to the contribution of underplating, there are a series of high conductivity layers develop in the crust and upper mantle. The depth of the lithosphere in northern Guangdong decreases from 100 km to 60 km from west to east, this feature reflects the cut effect of Pacific plate to the Eurasian plate;It characerizes as middle and low resistivity under 100 km in Chaozhou, the substance with middle and low resistivity is deduced as oceanic curst from the subduction of the pacific ocean.

Key words: northern Guangdong, Ruyuan-Chaozhou, magnetotellurics, electrical structure, geological significance