GEOPHYSICAL PROSPECTING EFFECT IN THE GRAPHITE-BEARING STRATA IN EASTERN LIAONING: A Case Study of the Diaoyutai Gold-Silver Deposit

Due to the graphite contained in the Gaojiayu Formation in Eastern Liaoning area, the anomaly value of high polarizability is often higher than that of ore-induced anomalies, while that of low resistance is commonly lower. That seriously affects the prospecting results of geophysical methods. In this paper, the exploration in Diaoyutai Au-Ag deposit is analyzed as an example. On the basis of the stratigraphic and lithologic structure, metallogenic geological conditions and ore-controlling and ore-host structures, the electrical properties of rocks and ores are measured. With IP intermediate gradient and AMT combined method, the abnormal response model is established for the graphite-bearing strata, by which the ore-induced anomalies are correctly identified and classified. The verification drilling shows a good result.