The heat transport properties of feldspar, one of the major minerals of the crust, are important for constraining the thermal state of the Earth’s crust. The thermal diffusivity (D) and thermal conductivity (κ) of two natural alkali feldspars, namely, perthite and albite (Ab), were simultaneously measured at high temperatures (300–873 K) and high pressures (0.8–3 GPa) using a transient plane-source method. The present results show that the D and κ of these alkali feldspars decreased with the increase in temperature, whereas the κ of perthite remained almost constant at above 450 K. The D and κ of these samples decreased by 24–35% and 8–21% when the temperature increased from 300 to 873 K, respectively, suggesting that phonon conduction may be the dominant mechanism. The D and κ of these samples also exhibited a positive pressure dependence as indicated by their positive pressure coefficients: 0.052–0.098 mm²s⁻¹GPa⁻¹ for D and 0.189–0.325 Wm⁻¹K⁻¹GPa⁻¹ for κ. Combining previous data with the results of this study, the D and κ of an intermediate albite-orthoclase solid solution can be reasonably estimated by an empirical model. Furthermore, the average κ of the crust was recalculated to accurately constrain the thermal thickness and temperature of the lithosphere. The present estimate suggests that partial melting can occur at shallow depths of the middle and lower crust, which may provide a new understanding of the low-velocity and high-conductivity anomalies revealed by geophysical observations in the crust.

长石（地壳的主要矿物之一）的热传递特性对于限制地壳的热态非常重要。在高温（300–873 K）和高压（0.8–3 GPa）下，同时测量了两种天然碱长石，即硫铁矿和钠长石（Ab）的热扩散率（D）和热导率（κ）。瞬态平面源法。本结果表明，d和κ这些碱性长石的随温度的增加而降低，而κ条纹长石的保持在高于450 K的几乎恒定的d和κ当温度从300 K升高到873 K时，这些样品中的分别下降了24-35％和8-21％，这表明声子传导可能是主要的机理。的d和κ这些样品也表现出阳性压力的依赖性可以通过正压力系数所指示的：0.052-0.098毫米²小号^-1 GPA ^-1为d和0.189-0.325了Wm ^-1 ķ ^-1 GPA ^-1为κ。将先前的数据与本研究的结果相结合，D和κ可以通过经验模型合理地估计中间钠长石-原正石固溶体的含量。此外，重新计算了地壳的平均κ以精确地限制岩石圈的热厚度和温度。目前的估计表明，部分熔融可能发生在中地壳和下地壳的浅层深度，这可能提供对地壳中地球物理观测所揭示的低速和高电导率异常的新认识。