The Prospectivity of Hot Spot Volcanic Islands for Geothermal Exploration

Abstract

The majority (>90%) of the World’s geothermal developments have been associated with volcanism adjacent to subduction zones at crustal plate boundaries. However the increased level of international interest in utilising geothermal resources for power generation, has directed attention to hotspot volcanic islands that are remote from subducting plate boundaries. This has been driven by the very successful development of geothermal resources in Iceland and Hawaii at so-called hotspots.
Over the past twenty years the origin and mechanisms of hotspot volcanics and mantle plumes has become a specialised field of study. In order to better assess the geothermal prospectivity of hotspot volcanic islands the questions must be asked - what other field associations, field relationships, chemical, mineralogical or petrological characteristics might be useful in such early assessments? What roles do size and age, magma type, and hydrological setting play in providing a suitable setting for high temperature geothermal systems? Seven hotspot islands are reviewed in the paper. They include Iceland, Hawaii, the Azores, Ascension, the Canary Islands, Samoa and Tahiti.
There are also strong economic drivers to encourage the development of such indigenous island resources for base load electricity supply on islands that are otherwise dependant on imported fuel oil.