Tracking the thermal properties of the lower continental crust: Measured versus calculated thermal conductivity of high-grade metamorphic rocks (Southern Granulite Province, India)

摘要: Abstract In this study, the bulk thermal conductivity (TC) of 26 rock samples representing different types granulite-facies rocks, i.e., felsic, intermediate and mafic granulites, from Southern Granulite Province, India, is measured at dry saturated conditions with optical-scanning method. Thermal also calculated modal mineralogy (determined by XRD EPMA), applying several mixing models commonly used in studies. Most rocks are fine- to medium-grained equigranular texture. All isotropic weakly anisotropic possess low porosities ( −1  K for felsic between 2.5 3.5 W m granulites 2.4 2.7 W m granulites. Considering data literature compilations, representative lower continental crust typically display values 2 3 W m ambient temperature pressure conditions. Depending on model mineral TC value calculations, could be properly fitted. For mean TCs, harmonic provides an almost perfect fit, a deviation −1 ± 6% (1 σ ). However, implication that correspondence would minerals pores predominantly aligned parallel, which apparent contrast texture studied here. The geometric mean, does not consider any layering or and, thus, should better harmony textural characteristics high-grade matches very well, if minimal TCs reported applied (mean 5 ± 8%). Thus, appropriate laboratory measurements (in terms sample size physical-chemical-mechanical condition) available, metamorphic anisotropy porosity satisfactorily good assessed mineralogy, using sets study. Further work required applicability compute other types, e.g., igneous sedimentary rocks.