| Abstract |
Four wells, a distance of 1 to apart, have been drilled at Orakeikorako, of Taupo. Cores recovered from below about contain hydrothermal mineral assemblages that include quartz, albite, adularia, illite, chlorite, epidote, calcite, pyrite and titanite wairakite, clinozoisite, siderite, apatite and leucoxene). The distribution of secondary minerals reflects the hydrological and thermal regime which is as high as Temperature of homogenisation measurements, obtained for 278 inclusions in quartz and calcite for 16 core depths, mostly match measured bore temperatures (eg. shallow levels and However, results also indicate that southern parts of the field have cooled appreciably,eg. OK1 (deep levels) and OK4 whereas northwestern parts have heated (eg. OK6:11 Freezing temperatures were obtained for 83 of the inclusions; the determinationsresulted in calculated apparent from 0.2 to NaCl equivalence. High apparent salinities in some inclusions is attributed to the presence of C02 in the trapped fluid.. The observations are consistent with a model whereby the hydrothermal fluid inclusion data, plus present surface subsurface conditionsrecord the evolution of the Orakeikorako system, which has clearly changed with time. |