INDUCED POLARIZATION RESPONSE ON CU-MO MINERAL DEPOSITS

Induced Polarization (IP) method is a non-destructive electrical geophysical technique and is often applied for mineral exploration and hydrological investigation. IP measures both conductive and capacitive properties of geologic materials, and it can be performed either in the time or frequency domain. Measurements performed in a spectral manner (spectral induced polarization, SIP) exploit the frequency dependence of subsurface properties and can be used for ore prospecting. In this study, we try to find SIP anomalies associated with Cu-Mo mineral in order to facilitate the mineral prospecting in the field. Total of 42 core samples from Xilamulun suture zone, Inner Mongolia were used in this study. The complex conductivity is measured over the frequency range 10^-3 to 10⁶ Hz. We observed that the real conductivities of all the samples have a significant positive correlation with the metallic grade, which the metallic simples (0.01~0.06 s/m) exhibit an order of magnitude higher that of non-metallic ones (2^-3~1.6^-3 s/m). The phases of metallic increased with frequency went higher. The phase responses of metallic rocks are < -200 mrad at frequencies < 10^-2 Hz but the non-metallic rocks (i.e. host rock) exhibit phase anomalies around -100 mrad at frequency range of 10^-3~10⁶ Hz. Furthermore, samples of main stages from porphyry deposits exhibit low phase response (<50 mrad). In order to fully interpret the data observed from core samples, we design synthetic samples with four-electrode columnar sample holders by mixing metallic with quartz gains to investigate the SIP responses from frequency-domain and SIP signature. The results could potentially help improve the accuracy of estimating metallic grade and mineral exploration application in this region.