1Depto. de Geotermia, Div. Fuentes de Energía, Instituto de Investigaciones Eléctricas, Apdo. Postal 475, Cuernavaca, Mor. 62000, Mexico
2Earlier publication of the author are also under the name of Surendra PAL
3Inst. f. Geowissenschaften, Johannes-Gutenberg Universität, Mainz, Germany
4Max-Planck-Institut f. Chemie, Abt. Geochemie, Mainz, Germany
5Present address of SPV is 3.