3D magnetotelluric imaging of the middle-upper crustal conduit system beneath the Lei-Hu-Ling volcanic area of northern Hainan Island, China

Abstract

We present a magnetotelluric study of the Lei-Hu-Ling volcanic system in the Haikou Volcanic Zone, Hainan, China. Data acquired from 111 broadband magnetotelluric sites was used to construct a 3D resistivity model of the magmatic system. The 3D inversion shows that a well-developed shallow low-resistivity zone in the southwest of the Changliu-Xiangou Fault corresponds to the Fushan depression, and a large conductor presents in the depths of 4–10 km underlying the Lei-Hu-Ling volcanic system. The deep conductor displays a N–S lineation oblique to the Changliu-Xiangou Fault, indicating that the fault does not control the deeper magmas path. We prefer to attribute the deep conductor to accumulation of high-salinity fluids in the storage zone with porosity of 1% to 1.6%, which was associated with the transportation of magmatic fluids and volatiles supplied by a partial melting zone at greater depths.