Coupled geodynamics in the formation of Cu skarn deposits in the Tongling–Anqing district, China: Computational modeling and implications for exploration

Abstract

The Tongling–Anqing copper district is an important mature copper skarn mining district in China. To better understand the localization of ore and thus facilitate deep ore exploration, computational modeling is used to investigate the coupled geodynamic processes during the syntectonic cooling of the ore-related intrusion, based on geological investigations of the Tongshan and Anqing deposits. The occurrence of brecciated diorite and skarn clasts in the ore and the sharp zigzag boundary of the ore body indicate that the copper ores were deposited after skarn formation and that they were located in some tensional spaces that are unevenly distributed along the contact zone between the felsic intrusion and sedimentary carbonates. The computational modeling results show that all of the skarn ore bodies are located in dilation zones close to the intrusion's contact, demonstrating the control of the dilation zones on the location of the skarn ore bodies, as a consequence of the coupling of geodynamic processes during the syntectonic cooling of the related intrusions. This recognition is helpful for selecting exploration targets in similar geological settings. Indeed, drilling into a deep dilation zone along the contact has resulted in the discovery of significant ore-body in the depth of the Tongshan mine, as the computational modeling predicted.