| Abstract |
Kawerau and Ohaaki geothermal fields have regional similarities - both occur close to the east margin of the TVZ, have shallow basement, and are not associated with a major rhyolitic caldera. The Kawerau basement slope into the TVZ is half as steep as at Ohaaki, and the south to north drop could be accommodated on two major faults. Predicting basement permeability fiom fault patterns is difficult, and may lead to erroneous well targeting. Kawerau greywackes belong to Waioeka petrofacies of the Torlesse, and have more plagioclase, but less quartz and argillitethan the Axial-A petrofacies greywackes of Ohaaki. Because of this, the Kawerau basement may sustain open fiactures to greater temperatures and depths than Ohaaki basement. |