Sanders, F.; Seward, A.M.; Sagar, M.W.; Faure, K. 2024 Thermal properties of Zealandia basement rocks: results of Thermal Conductivity Scanner measurements, 2023. Lower Hutt, N.Z.: GNS Science. GNS Science report 2024/08. 127 p.; doi: 10.21420/CA2Y-TC78
Abstract
The density, apparent porosity, and thermal properties of 51 rock samples (including eight duplicates), collected from several regions around the South Island, New Zealand, were assessed in 2023 as part of the Understanding Zealandia – Te Rui-a-Maui (UZTRM) SSIF research programme. This is the second batch of measurements undertaken for the UZTRM programme and accompanies the Sagar et al. (2022) report. The collected rock samples represent a range of lithologies and basement rock terranes, including sedimentary (clastic mudstone, clastic sandstone, limestone), igneous (ash-rich tuff, diorite, spilite, tonalite, granitoid, gabbroic rock), and metamorphic (dioritic orthogneiss, granitoid orthogneiss, and greyschist) lithologies. Density and apparent porosity were determined using standard gravimetric methods. Amongst the 51 individual samples, dry densities range between 2.1 and 3.9 g/m3 and apparent porosity ranges from <0.1 to 26%. Thermal properties were measured for 48 of the samples using a Thermal Conductivity Scanner. Of these samples, thermal conductivity ranges between 1.36 and 4.59 W/mK, and thermal diffusivity between 0.74 and 1.71 x 10-6 m2/s. Density, apparent porosity and thermal properties are compared between samples classified by lithology type, and between similar lithologies derived from different basement terranes. Some differences between the properties of different lithologies are evident, but the small sample population size of each lithology group precludes the determination of any statistically significant differences between lithologies. (auths)
