Stable Isotope Geochemistry of the Tongonan Geothermal System, Leyte, Philippines

Abstract

Stable isotope and geochemical data on samples from natural features, shallow wells and deep wells collected over a number of years from the area of Leyte have been evaluated. The variations in the isotopic compositions of the thermal waters are used to describe natural processes within the system. The effect of the of the deep wells on the isotope data is formulated. Water from the Tongonan wells shows an oxygen-18 shift of 5 ,which is larger than at Wairakei and Broadlands, probably in part became of the high temperatures at Tongonan, Recent measurements indicate that the deuterium shift is very much than previously thought. Isotopic measurements of methane in the gases suggests differing from the Eastern and Central Philippine faults.