The Geobattery model: a contribution to large scale electrochemistry

In geophysics, minima of the static electrical potential along the Earth's surface are called self-potential (SP) anomalies. In the immediate vicinity of the Continental Deep Drilling (KTB) in the Oberpfalz (Bavaria, Germany) an SP anomaly has been observed amounting to -0.6 V. This fact has been taken as the occasion to start an attempt to clarify the origin of the SP anomaly near the KTB, utilizing measurements of various parameters (electrical potential, redox potential) within the drilling hole. According to a theory by Sate and Mooney, SP anomalies may be caused by electrochemical processes in the Earth crust similar to a galvanic cell: a steeply inclined electronic conductive mineralization connects regions of different redox potential. Such a configuration forms a giant electrochemical cell called 'geobattery'. In order to develop an adequate algorithm for calculating geobatteries, laboratory simulations with synthetic materials were carried out accounting for the redox potential field, the position of the electronic conductor, and kinetic parameters of the electrochemical reactions which occur at the surface of the mineralization. (C) 1997 Elsevier Science Ltd.