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Calculation of thermal conductivity of low-porous igneous rocks from modal mineralogy

This data set compiles the raw data that were used to calculate the bulk thermal conductivity (λb) of low-porosity igneous rocks from modal mineralogy, porosity, and nature of saturation fluid. It compliments a paper by Fuchs et al. (2018) to which it represents supplementary material. The paper reports the result of seeking out the mixing model(s) providing the best match between measured (λb.meas) and calculated bulk thermal conductivity (λb.calc) for low-porous igneous rocks. The study encompassed 45 samples representing various geological provinces in eight countries.Our suite of samples covers the entire range from ultramafic (gabbro/diorite) to silicic rocks (granite), straddling the range 36–76 wt.% SiO2 (corresponding quartz range: 0–45 vol.%), and includes both such of alkaline, peralkaline, metaluminous, and peraluminous affinity. Assessment of the quality of fit involved all frequently applied mixing models that consider quantitative data on modal mineralogy.Our evaluation clearly demonstrates that λb of low-porous igneous rocks, irrespective of being ultramafic or felsic, could be indirectly calculated from their mineral content with an acceptable error by employing the harmonic mean model. We show that the use of the harmonic-mean (HM) model for both rock matrix and porosity provided a good match between λb.meas and λb.calc of < 10% deviation (2σ), with relative and absolute errors amounting to 1.4 ± 9.7% and 4.4 ± 4.9% respectively. The results of our study constitute a big step forward to a robust conclusion on the overall applicability of the HM model for inferring λb of low-porous, mafic to silicic magmatic and metamorphic rocks with an acceptable magnitude of error.The data included in this data publication are the tables and plots described in Fuchs et al. (2018). They are provided in Excel (.xlsx) and .csv Formats and are further described in the data description file. The diagrams are only included in the Excel version.

Thermal diffusivity–porosity data used in the evaluation of the Goto-Matsubayashi modified geometric model for continental sedimentary rocks

This data set compiles the raw data used to evaluate the performance of the Goto & Matsubayashi model for continental sedimentary rocks ( Goto & Matsubayashi, 2009). It reports thermal diffusivity (α) and porosity (φ) data for two suites of rock, quartz sandstones of varying porosity and clastic and carbonate lithologies of variable porosity and modal mineralogy.The rock collection involves roughly 120 samples (from boreholes and outcrops) with porosities between 0 and 35%, on which the operability of the Goto & Matsubayashi modified geometric mean model (mGM) was evaluated and quantified.Our study confirms the operability of the mGM for consolidated quartz-rich sandstones and implies a reasonably good performance of this model also for mineralogically more complex sedimentary rocks. This model was also proven to be an appropriate tool to convert thermal diffusivity data obtained on air-saturated samples into such reflecting water-saturated conditions. Altogether, our study suggests that the mGM is suited to model thermal-diffusivity data of all types of sedimentary rock of whatever porosity and chemistry of the pore fluid.The data reported in this data publication are the basis for tables and plots published by Fuchs et al. (2020). Data are provided in tab-delimited text format and described in detail in the associated data description.

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