Proceedings of the 7th New Zealand Geothermal Workshop 1985. Oxygen isotope exchange in relation to hydrotermal alteration of rocks. New Zealand Geothermal Workshop [7, 6-8 Nov. 1985, New Zealand].

Absar, A.

1985

1067
CIENA

0-86869-065-1

Oxygen isotope data from unaltered to intensely altered rocks indicate that substantial 18o-exchange precedes the visible effects of hydrothermal alteration. The cumulative water to rock mass ratios calculated from the 18o-data are generally less than 1; values more than 1 are less sensitive to 18o-exchange. These ratios correspond to times when rock and fluid attained Ù 18o compositions close to their current values, a situation that probably occurs during the early part of the history of most geothermal systems. Water/rock ratios which are calculated on the basis of leaching and addition of some common and rare alkalies during hydrothermal alteration, however, are in comparison higher by two orders of magnitude. This is because these latter ratios relate two much slower processes and are affected by subsequent fluid throughput during the entire history of the system. ABSTRACT. INTRODUCTION. RELATIVE RATES OF 180-EXCHANGE AND HYDROTHERMAL ALTERATION. WATER TO ROCK RATIOS. DISCUSSION. CONCLUSIONS. ACKNOWLEDGEMENTS. REFERENCES.

Presenta gráfs.

NUEVA ZELANDIA; ENERGIA GEOTERMICA; GEOTERMIA; INGENIERIA DE RESERVORIO; CAMPOS GEOTERMICOS; MINERALES; ANALISIS QUIMICO;