Fine interpretation of magnetic data for a concealed mineral deposit: A case study of the Fe-polymetallic deposit from Western China

Abstract

We interpret the magnetic anomalies for exploration and characterization of the Galinge iron polymetallic deposit, which is the largest iron polymetallic deposit in Western China. This undeveloped deposit is completely concealed by the thick Quaternary sediments, presenting an exploration challenge. A lot of drillholes have been implemented focusing on the strong magnetic anomaly centers, while the relationship between magnetite-bearing and non-magnetite-bearing drillholes is unclear, and the metallogenic regularity in the whole area needs to be further studied. The edge detection is applied on the downward continued field to resolve individual magnetite ore bodies and enhance possible concealed ore bodies. Three anomaly belts trending NE-SW with a total extension length of ∼11 km are first revealed. Combining the sharper images from the enhanced magnetic anomaly and the drillholes, we infer that the deposits would be related to the syncline structure. Forward modeling confirms the inferred three belts of the ore bodies and also shows possibly two layers deposits in which the deep layer would be located at a depth of ∼1000 m. Although the deeper deposit results in a very smooth and low amplitude magnetic anomaly, the forward modeling shows that the anomalies from both the shallow magnetite and the inferred deep one fit the observed anomaly better. One deep drillhole reveals the fact that the magnetite is existed at a depth of ∼1000 m which highlights the interpretation of the deep deposit. The results show the contribution of the fine processing techniques which would be used to distinguish zones of potentially concealed mineralization.