Sampling Volume of the NEOCHIM Electrogeochemical Method

Abstract

The poorly known CHIM electrogeochemical exploration method, a hybrid geophysical/geochemical method, is claimed by its Russian developers io be especially useful in exploration for deeply buried mineral deposits.The U.S. Geological Survey began research on the CHIM method in 1989. This research iclgntified significant problems related to electrode design, resulting in development of an entirely new type of electrode. This new electrodc now permits soil ion extractions approximating that required by Faraday's law of eleètrolysis. Based on a Faradaic extraction, the volume of soil sampled by a CHIM extraction is shown to be V = mpQ, where m is ionic mobility, p, earth resistivity, and Q, the electric charge expended. For typical CHIM operating parameters these volumes may be as much as 106 times the volumes of soils typically analyzed in conventional geochemical methods. It is this large difference in sample volume that provides advantages for the CHIM method.