Local uplift and copper metallogenic prospect in the Luzong ore district, Eastern China: evidence from 3D magnetotelluric imaging

摘要

The Lujiang-Zongyang (Luzong) ore district is well known for porphyry iron deposits that are mainly located in the Luzong volcanic basin, an important iron ore area in eastern China. Since the discovery of copper deposits in the ore district, regional tectonic evolution and geodynamic processes have become important issues for further mineral exploration. However, most prior research focused on geology and metallogeny, and little attention has been paid to the deep structure and its relationship to mineralisation. To understand this problem further, data were collected at 76 broadband magnetotelluric stations in the central Luzong basin, and then inverted in 3D using the nonlinear conjugate gradient method. Based on the inverted 3D electrical model, we consider that hot material upwelled beneath the lower crust in the centre of this region, where the crustal resistor is shallow and thin compared with surrounding resistors. We infer that one local uplift belt existed upon the upwelling material. The regional high aeromagnetic anomalies and low residual gravity anomalies hint at the presence of a shallow volcanic basin and upper mantle material. Because of the copper metallogeny in the adjacent district, we suggest that the local uplift belt in the centre basin has great potential for copper prospecting.