Investigating copper-molybdenum polymetallic deposits using audio-magnetotelluric sounding: A case study in the Shangri-La area, Yunnan Province, China

Abstract To analyze the deep geological structures of a copper-molybdenum polymetallic ore district located in the Shangri-La region, Yunnan Province, China, the audio-frequency magnetotelluric (AMT) sounding method was carried out. This approach accurately determined the electrical and structural characteristics of the subsurface in the mining area. Ore-prospecting indicators based on AMT data summarized the relationship between resistivity anomalies in AMT profiles and different types of orebodies: vein-like or columnar low-resistivity zones at shallow depths corresponding to intermediate- to low-temperature hydrothermal gold, lead, and zinc polymetallic orebodies; areas exhibiting columnar medium or medium-low resistivity characteristics indicating the presence of skarn-type or porphyry-type copper-molybdenum polymetallic orebodies; and intermediate-acid igneous rocks (e.g., diorite porphyrite and porphyry) displaying medium resistivity features. Several potential deep concealed orebodies were delineated, indicating that large-scale porphyry-type copper-molybdenum orebodies may exist at greater depths. The findings suggested that the AMT method is an effective geophysical tool for detecting concealed rock (ore) bodies in the Donglufang copper-molybdenum polymetallic and similar deposits.