Spontaneous potential method

Spontaneous potential (SP) method (also called self-potential) is based on measurements of natural electric fields in rocks. Physicochemical processes that proceed in rocks usually cause these type of fields. These processes are:

• redox reactions between electron-conductive rocks like graphite, most of sulfides, magnetite etc.) and interstitial water;
• water filtration in the pores of rocks;
• concentration gradient of salts dissolved in the interstitial water;
• temperature gradient. 

Sources of the most powerful electric fields (up to 1.2 V) are often connected to redox reactions on either boundaries of carbonic bodies (graphite) or massive sulfide ores saturated by pore water. The SP method stands out among other geophysical methods by its simplicity. The equipment consists of two non-polarizing electrodes, a wire and voltmeters with big input resistivity. Thus, the SP measurement technique is cheap and high-performance.

Despite of its ease, the SP method is suitable for the solution of many geological tasks like:

• mapping of carbonaceous bodies which often are host-rocks at coarse gold deposits
• exploration of massive sulfide bodies at copper-pyrite and polymetallic deposits.