Surface Alteration Between Orakeikorako and Te Kopia Thermal Areas

Abstract

Volcanic facies models for andesitic stratovolcanoes have been utilised in volcanological studies and in exploration for mineral deposits. A four facies model has now been successfully applied to establish a stratigraphic sequence at Wayang Windu geothermal project where overlapping andesitic volcanic piles of similar lithological character are present in the wells. Formational boundaries can be defined where there are rapid non-systematic changes in facies, and the proximity to eruptive centres defined by lateral gradational changes in facies. Structural data and primary mineralogical indicators of different stratigraphic units are in agreement with the facies as are K-Ar dating and geochemical analysis of fresh rocks.