Subsurface Architecture of the Tuina Prospect and Its Relationship to Fluid Migration in Mineral Deposit Formation

The Tuina prospect is situated in northern Chile, approximately 50 km east of Calama in the Antofagasta Region. It lies within the Eocene-Oligocene metallogenic belt, which is home to world-class copper deposits, including Chuquicamata, El Abra, and Radomiro Tomic. To characterize the subsurface architecture, we deployed a temporary seismic network of 37 geophones and applied Local Seismic Tomography to derive seismic velocity models. The results show intermediate Vp/Vs values in the prospect area, suggesting a highly fractured environment consistent with surface geological data. Additionally, we identified a high Vp/Vs anomaly with a northwest orientation, reaching depths of up to 20 km and intersecting the anomaly associated with Tuina. We propose that this structure is not a simple lineament, as previously suggested, but rather a concealed fault system controlling the eastern boundary of the Eocene-Oligocene metallogenic belt. In this context, the so-called Calama-Olacapato-El Toro lineament represents a complex fault system playing a key role in the region’s structural evolution and mineralization. Based on this, we present a five-stage conceptual model explaining how fluid migration from subduction enables the formation of mineral prospects controlled by this fault system. The tomography results correlate with surface data, demonstrating the method’s effectiveness for geophysical exploration.