Crustal Structure and its Control on Gold Mineralization in Wulong Goldfield, Liaodong Peninsula of China: Constraints from Ambient Noise Tomography with a Short-Period Dense Array

Abstract

During the destruction of the North China Craton in the Mesozoic era, a significant gold mineralization event occurred, leading to the formation of the world-renowned Jiaodong Gold Province. The Liaodong and Jiaodong regions have similar tectonic backgrounds and geological evolution histories. However, the confirmed gold resources in the Liaodong region are only one-tenth of those in Jiaodong. To reveal the controlling factors behind the differences in mineralization between these two regions and explore the deep mineralization prospects in the Liaodong region, we conducted a short-period and high-density array (WSP array) in the Wulong Gold Concentrated Area, the largest goldfield in the Liaodong region. Using data recorded by 334 SmartSolo seismometers for one month, we applied ambient noise tomography to obtain the S-wave velocity structure of the crust down to a depth of 3.5 km beneath the Wulong goldfield. The velocity structure revealed the presence of two sets of low-velocity anomalies trending NNE and NW, respectively, in the shallow crust (shallower than 1.5 km) of the Wulong goldfield, while two high-velocity anomalies were identified at deeper depths (1.5–3.5 km). By combining these findings with the geological characteristics of the Wulong goldfield, it was discovered that the high-velocity anomaly (II) corresponds to the Sanguliu granitic body exposed at the surface, while the high-velocity anomaly (I) could be a concealed intrusive body. The shallow low-velocity anomalies are the result of hydrothermal alteration caused by mineralizing fluids along the NNE- and NW-trending faults. The intersection of these two sets of faults, where the low-velocity anomalies exist, represents the center of the hydrothermal activities. Based on these observations, it is proposed that the area between the Sanguliu granitic body and the concealed intrusive body in the northwest has favorable metallogenic conditions. The intersections of the NNE- and NW-trending faults show the high potential for forming large to super-large altered rock-type gold deposits.