Metallic mineral exploration by using ambient noise tomography in Ashele copper mine, Xinjiang, China

Abstract

Rapid advances in the seismic exploration method have allowed its application in metallic mineral exploration. However, 2D seismic profiles are often insufficient to describe the shape and areal extent of ore-bearing rock masses away from survey lines. Although more complete, collecting 3D seismic data is expensive, time consuming, and may require considerable investment in surface access. The combination of ambient noise tomography and 2D seismic reflection exploration methods can produce acceptable results relatively quickly and at a low cost. The enormous Ashele copper deposit in northwest China is a typical deposit formed by volcanic eruption. It is rich in resources and possesses good prospecting potential in its deeper and peripheral areas. We performed ambient noise tomography to investigate a near-surface 3D S-wave velocity ([Formula: see text]) structure above a depth of 0.7 km in the Ashele mining area (approximately 8 × 12 km) using 25 days of continuous ambient noise data. From the combined interpretation of the 3D [Formula: see text] structure and the existing 2D seismic reflection profile, we infer that there may be ore-bearing rock masses in the western and northern sides of the research area. We report the discovery of an ancient volcano at a depth of 500 m on the western side of this region. The banded velocity anomalies and the existence of the ancient volcano signify the formation process of a bimodal volcanic rock association. It has been proven that the combination of ambient noise tomography and 2D seismic reflection exploration methods can produce important results in metallic mineral exploration. Therefore, ambient noise tomography can be used as an economical, convenient, and efficient method for future explorations, complementing the 2D seismic reflection exploration method.