Scientific Drilling in the Taupo Volcanic Zone? Exploring Intense Volcanic and Geothermal Processes in a Rapidly Rifting Arc

Abstract

Scientific drilling programmes yield game-changing datasets to improve knowledge of Earth processes, and are pushing the limits of conventional geothermal uses. The Taupō Volcanic Zone (TVZ) in Aotearoa New Zealand is the ideal place to study the interactions between tectonic, magmatic, volcanic, geothermal and microbiological processes in a rapidly rifting young volcanic arc that hosts numerous rhyolite calderas, andesite and dacite cones. Unravelling the heat and mass transport mechanisms in the TVZ has direct implications for understanding the entire subduction factories, better assess associated earthquake and volcanic hazards, and sustainably use geothermal resources which, in New Zealand, are of great significance to Māori. Since the 1950s, extensive geophysical, geological and geochemical datasets have been collected throughout the TVZ. Geothermal drilling up to 3.2 km depth and 340°C into near-neutral pH reservoirs has provided a window into the sub-surface TVZ. This lead to discoveries on geothermal, continental rift and arc systems. To expand the exploration of TVZ subsurface with in-situ data outside conventional geothermal reservoirs, we propose the establishment of a scientific drilling programme. Scientific drilling will advance our understanding of: (1) feedbacks between the volcanic arc and an active rift; (2) controls on the timing and rates of volcanic and seismic events; (3) large-scale hydrology and magma systems; and (4) the microbiological diversity and function of the deep biosphere. We present the Okataina Volcanic Center, an accessible rhyolitic caldera where extensive surface data is already available, as one of the candidate areas with exciting potential to answer these research themes. At these very early stages, we seek to build strong relationships with Māori groups, and a multi-disciplinary national and international team, to develop the idea of a TVZ scientific drilling. This programme will aim to test fundamental geoscientific and geothermal concepts within the TVZ exceptional geological setting, and strengthen linkages with other ongoing geothermal scientific drilling programmes.