Effectiveness of transient electromagnetic method (TEM) used for the localization of Pb–Zn ore bodies at the Cho Don deposit, province Bac Can, North Vietnam is appraised based on the modelling processes results. Conductive Pb–Zn ore bodies hosted in high-resistive limestone are in good conditions for the application of the TEM. The modelling process relays on the calculation of the voltage decay in time domain formed from the induced magnetic field diffusing into the study medium, when a pulse current with a given frequency is flowing in a transmitting loop coil. The model results show that the power current of 1 A transmitted from the coils with 100 or 400 m of size is effective for localization of the Zn–Pb ore bodies. However, the resolution and penetration depth of the TEM with a coil of L = 100 m is better and shorter in comparison with those in the case using the coil L = 400 m.
The IOCG Sin Quyen deposit is located in the Red River shear zone of North Vietnam. The ore bodies are known as hydrothermal veins and are hosted in Proterozoic metapelite. A block modelling approach was used to build a 3D model of the ore bodies. An analysis was carried out on Surfer 11 computer software using the archival data recorded from several dozen boreholes distributed within the study area, as well as data obtained from the mineral and chemical analysis of 50 samples collected recently in the deposit. The ore bodies generally trend in a NW-SE direction with an average azimuth of 107° and dip of around 70°.The Cu content in the ore bodies is inhomogeneous. In the bed extension direction, the exponential correlation of Cu concentration in ore bodies is recognized within 2,500 m, while in the direction perpendicular to the bed strike, the exponential dependence is observed on 500 m of distance. The high-grade mineralisation of copper within the ore bodies is often at the altitude interval from ∼100 m to ∼150 m above sea level (asl). These bodies are also rich in uranium and gold bearing minerals. The total resources of Cu, U and Ag were estimated and amount to 361,000; 12.7 and 11.87 tonnes respectively. The model indicates the downward extension of some ore bodies to below 300 m beneath the ground surface.
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