Prediction of hidden ore bodies by synthesis of geological, geophysical and geochemical information based on dynamic model in Fenghuangshan ore field, Tongling district, China

Abstract

Although the Tongling district is one of the most important Cu districts in China, exploration strategies need to be urgently updated to achieve a more predictive method for discovering hidden ore bodies. This paper presents a case study showing how new exploration strategies were developed and successfully used to discover a hidden ore body in the Fenghuangshan ore field of the Tongling district. All previously discovered ore bodies in the Fenghuangshan ore field were Cu skarn deposits located where dilational fault zones cut the contact zone of the Xingwuli granitoid complex. The features of the ores and the related magmatic rocks and hydrothermal alteration suggest that porphyry copper deposits are also likely to be present in the ore field. After assessing spatial controls on ore formation, ore-related indicators numerical simulating the coupled thermal–hydrological–mechanical processes during syn-deformation cooling of the Xingwuli Intrusion were used to choose a target area to the south of the Fenfhuangshan mine. In this target area, we have carried out an exploration program involving mapping, rock chip sampling for Cu in the fractured and altered rocks, and pesu-random triple frequency induced polarization (IP) and the controlled source audio-frequency magnetotellurics (CSAMT) surveys. Synthesis of the data obtained in this program identified a target that was subsequently drilled. This test hole demonstrated the presence of high grade Cu ores typical of both skarn and porphyry copper deposits.