Application of spectral time domain induced polarisation method to resolve orebody characterisation

Abstract

One of the most important issues in searching for metallic ores is to discriminate between different types and textures of mineralisations. One of the methods capable of deriving such information is the spectral induced polarisation (SIP). With advances in the time domain IP receivers it is possible to get SIP data with no more additional costs. Therefore using Cole-Cole impedance model for the subsurface it is possible to calculate the apparent Cole-Cole parameters by a curve matching technique in a least squares sense. In the current study, SIP measurements have been obtained using six chargeability slices of the transient decay curve after a 2 seconds square wave current on time at the Irankuh lead and zinc ore deposit complex. It is shown that the SIP measurements will give additional valuable textural and structural information which can be of great help in determining and delineating ore blocks for a systematic exploration program. It was found that the increase in time constant is associated with the ore zones with continuous and greater grain size of IP sources. The average frequency exponent for the vein type ores was found to be about three times larger than that of the disseminated ore zones. Also from the true chrageabilities obtained from SIP analysis, the location of the vein type ores was delineated with a higher resolution. Finally due to its cost efficiency and faster field operation it is suggested to collect SIP data for exploration targets where the textural information can play a very important role in dividing ore to the blocks with similar characteristics.