Towards a New Zealand Crustal Temperature Model

Abstract

New Zealand has a long history of developing geothermal resources for electricity generation, and to a more limited extent, direct use applications. An understanding of New Zealand’s thermal regime is important in expanding the use of geothermal energy, particularly direct use. However, the crustal temperature distribution across much of New Zealand is not well known. Good quality crustal temperature measurements are sparse and unevenly distributed, with distribution being driven by the locations of historic resource exploration and groundwater monitoring bores. Furthermore, New Zealand’s heat flow regime is complex with strong influences from fluid advection and convection, as well as transient processes (e.g., recent sedimentation and erosion) related to this relatively young and highly tectonic landmass. Predicting crustal temperatures is further limited due to the lack of good data on thermal properties of crustal rocks. We are developing a national temperature map using a 1D transient heat flow modelling approach. To support the model, we have established thermal properties measurement capability and are using measurements from this in conjunction with geochemical and mineralogical data to estimate thermal properties. Development of other model inputs is ongoing. This paper will present progress towards the collection of new thermal property data, compilation of historic temperature measurements, and their integration in a national temperature model for New Zealand.