The Taupo Volcanic Zone (TVZ, New Zealand) is a NE-SW fault controlled volcano-tectonic depression, about 350 km long and 60 km wide, infilled by Quaternary volcano-sedimentary rocks with underlying faulted Mesozoic greywacke basement. The depth of the basement is constrained by drillholes in several geothermal fields, including at Ohaaki, Kawerau, Rotokawa, Ngatamariki and Tauhara. At Wairakei, Mokai and Mangakino geothermal fields, the basement has not yet been encountered, although deep wells of more than 2.5 km vertical depth provide insights on the depth of the basement at these locations, and constraints on major structures (e.g. faults, caldera) affecting the TVZ. The new capabilities of Leapfrog Geothermal allow complex geological and structural frameworks to be modelled. Here, regional and field specific geology, structural measurements, and gravity data interpretations are combined with historical and new geothermal drillhole data to model the surface of the greywacke basement in 3D. The ability to model the greywacke basement in a 3D interface provides new insights regarding the geological and structural framework of the TVZ, and information that impacts our understanding of its rheology and controls on deep-seated permeability. The model provides an integrated and innovative tool to support future development of New Zealand’s high enthalpy (>250°C) geothermal resources.

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