Below are some highlights of activities and changes from the last year, by project:
Goal: searching for prospective locations for accessing supercritical fluids, and delineating potential resources in the Taupō Volcanic Zone (TVZ).
- A published study on magmatic degassing in the TVZ crust concluded that most of the geothermal systems are fed by heat conducted from deeper (>6 km) basaltic and rhyolitic magmas. Metals in fluids in geothermal systems could be sourced from both basement and rare, extremely diluted, magmatic fluids.
- A published study details a step change in the interpretation of basement terrane geometry under the Taupo Volcanic Zone (TVZ), using analysis of basement rocks brought to the surface in volcanic eruptions (xenoliths). This work provides a useful, 10-100 km scale context for more detailed investigations of TVZ geothermal systems.
- A published study on analysis of 18O/16O ratios of TVZ magmas and crustal basement terranes concluded that that the interface between TVZ magmatic and geothermal systems is a dynamic zone, where proximity between deep-circulating water and shallow magma bodies leads to large-scale interactions between magmas and altered materials. These are ideal conditions in which to search for supercritical fluids!
- We have developed and implemented a new 3-D finite element MT inversion code (FEMTIC) - a more advanced mesh design allowing topography to be incorporated and mesh to be adaptively refined around areas of interest, making computation more efficient and results better able to be placed in context with other models. We are working on combining the MT resistivity model with relocated seismicity.
- We are working on a new heat flow map of New Zealand. Depth to base of magnetic sources analysis has produced the first map of the depth to the Curie point for a portion of Zealandia continent, including New Zealand.
Goal: investigating chemical characteristics of supercritical fluids and their interactions with rocks and minerals under supercritical conditions.
- A new empirical equation for quartz solubility was developed, covering a wide range of temperatures and pressures relevant to supercritical geothermal systems.
- A generic large-scale 3D model of a typical geothermal system was developed. This model serves as a powerful tool for testing various brine production and injection scenarios and assessing CO2 sequestration potential in New Zealand's geothermal fields. The model also facilitates investigations into mineral alteration, fluid chemistry evolution, and porosity and permeability feedback effects on fluid flow.
- Our specialist high temperature-pressure geochemistry equipment was used to conduct an experimental study on the potential of Rhenium (Re) and Indium (In) as geothermal tracers under subcritical, super-hot and supercritical conditions.
- A published study examined reactive transport modelling of a high pressure and temperature laboratory experiment that simulated the reaction between unaltered tholeiitic basalt and distilled water under subcritical conditions (350°C and 490 bar).
Goal: translating supercritical research and forming an engaged stakeholder community.
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