Application of the Magnetic Geophysical Method to Exploration of the Potassic Zone in Some Porphyry Copper Deposits (Iran)

Abstract

Haftcheshmeh, Masjeddaghi and Nowchun are three giant porphyry systems located in Iran. Because of the presence of potassic alteration outcrops in the Haftcheshmeh ore deposit (NW Iran), we decided to detect borders of this alteration zone by a ground magnetic method. Goal of exploration is to understand the distribution of concentration in porphyry systems, as the level of magnetization commonly differs across alteration boundaries. Further, 3D interpretation of magnetic data is important to improve our understanding of geology and alteration in the system. In this paper, qualitative and quantitative results of geophysical surveys are presented in the form of total field intensity, second derivative, upward continuation and pole reduction maps. Comparison of magnetic results with borehole logging provides a good pattern to a field geologist to assign and guide an exploration project. According to this pattern, all drill holes in Haftcheshmeh, Masjeddaghi and nowchun porphyry system were designed. According to the results for the mentioned copper systems, anomalous magnetic features are related to the sub-volcanic intrusions and high anomaly zones over the potassic alteration probably show the existence of magnetite. The potassic zone pattern can be used as a key in all further exploration of porphyry systems.