| Title | Preliminary Stable Isotope Investigations of Acid Fluids in Geothermal Systems of the Philippines |
|---|---|
| Authors | Robinson, B.W., Villasenor, L.B. and Clemente, V.C. |
| Year | 1987 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | To determine the of the sulphate in the acidsulphate fluids of the Bacon-Manito and Palinpinon Geothermal Projects, the sulphur isotopic compositions of gas, elemental sulphur, dissolved sulphate, anhydrite from well blockages and pyrite and anhydrite from well cores were measured. The H2S gas has values around i n the geothermal centres; this suggests an ultimate magmatic origin with no gas present in the geothermal areas. Oxidation of this in the near surface environment produces acid-sul phate springs whose sulphate has similar values to the More positive values are produced by the sulphate starting to equilibrate isotopically with the under deeper, hotter conditions, a process which i s accelerated by a low Elemental sulphur is also formed by oxidation gas with a kinetic isotope effect of at least 4/00 but it does not appear to be a contributor to the acid fluids. Anhydrite from the cores and scraper samples from 1 blockages generally exhibit dissiniilar and values showing that the blockages were formed under different conditions to those i n the geoloqic past. These new conditions have presumably been caused by the drilling which promoted mixing of shallow rich waters with deep Ca-rich thermal waters. |