ABSTRACT

Samples of schist, protomylonite, mylonite and ultramylonite from the hanging wall of New Zealand’s Alpine Fault were measured using a transient plane source, yielding mean bulk thermal conductivity of 2.04 ± 0.33 W m^–1 K^–1 in a dry state and 2.78 ± 0.51 W m^–1 K^–1 in a wet state at room temperature. Corresponding thermal diffusivity is 1.35 ± 0.32×10^–6 m² s^–1 in a dry state and 1.72 ± 0.27×10^–6 m² s^–1 in a wet state. Thermal conductivity and diffusivity calculated from the mineralogical composition of cuttings from the DFDP-2B borehole in Whataroa Valley and previously published thermal properties of minerals are 3.26 ± 0.16 W m^–1 K^–1 and 1.56 ± 0.08×10^–6 m² s^–1, respectively. We attribute the significant difference in thermal conductivity to regional mineralogical variations in composition of rock samples versus borehole cuttings. Anisotropy of thermal properties is inferred to exist on a centimetre scale, due to competing effects of aligned quartz veins, minerals, and microfractures; but our measurements do not confirm significant anisotropy. Radiogenic heat productivity calculated from geochemical data and a gamma log in DFDP-2B (1.8–2.1 μW m^–3) falls within the previously reported range for greywacke and schist.

摘要

使用瞬态平面源测量了来自新西兰高山断层挂壁的片岩、原糜棱岩、糜棱岩和超糜棱岩样品，在干燥状态下产生的平均体积热导率为 2.04 ± 0.33 W m ^–1 K ^–1和 2.78 ± 0.51 W m ^–1 K ^–1在室温下处于湿润状态。对应的热扩散系数在干燥状态下为 1.35 ± 0.32×10 ^–6 m ² s ^–1和 1.72 ± 0.27×10 ^–6 m ² s ^–1处于潮湿状态。根据 Whataroa Valley DFDP-2B 钻孔岩屑的矿物成分计算得出的热导率和扩散率以及之前公布的矿物热特性分别为 3.26 ± 0.16 W m ^–1 K ^–1和 1.56 ± 0.08×10 ^–6 m ² s ^{– 1}， 分别。我们将热导率的显着差异归因于岩石样品与钻孔岩屑成分的区域矿物学变化。由于排列的石英脉、矿物和微裂缝的竞争效应，推断出热性质的各向异性存在于厘米级；但我们的测量并未证实显着的各向异性。根据地球化学数据和 DFDP-2B 中的伽马测井 (1.8–2.1 μW m ^–3 )计算出的放射热生产力属于先前报告的灰岩和片岩范围。