Electrical conductivity of alkali feldspar solid solutions at high temperatures and high pressures

Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

“…The activation enthalpy for gneiss was close to the values for granite at the lower and higher temperature ranges. The activation enthalpies for albite and K-feldspar were 0.84 and 0.99 eV, respectively (Hu et al, 2013). With increasing pressure, the electrical conductivity of gneiss increased accordingly.…”

“…The symbol R 2 is denoted as the fitted correlation coefficient. cal conductivity of K-feldspar is 1 order of magnitude lower than albite, and K + and Na + ions are the charge carriers of Kfeldspar and albite, respectively (Hu et al, 2013). As shown in Fig.…”

“…Feldspar, quartz and biotite are the dominant minerals in the gneiss samples. Previous studies have suggested that the conduction mechanism for feldspar minerals is ionic conduction and the charge carriers are K + , Na + and Ca 2+ (Hu et al, 2013). The conduction mechanism for biotite has not been studied, whereas the charge carriers of phlogopite were proposed to be F − and K + .…”

“…As for the chemical compositions, the contents of SiO 2 for gneiss are lower than those of granite samples, and the contents of the calc-alkali ions are approximate between gneiss and granite samples. Hu et al (2013) demonstrated that the electrical conductivity of alkali feldspar significantly depends on the value of Na/(Na + K). This suggests that the electrical conductivity of gneiss is affected by the total content of alkali and calcium ions, as well as the ratios between various ions.…”

“…Hence, it is crucial to comprehensively measure the electrical conductivities of minerals and rocks that are distributed in the deep Earth. A series of electrical conductivity results of the main minerals and rocks have been reported in previous studies under high temperature and pressure conditions (Fuji-ta et al, 2007;Hu et al, 2011Hu et al, , 2013Dai et al, 2012;Yang et al, 2012;Sun et al, 2017a). However, the electrical conductivity of most metamorphic rocks has not been explored at high temperature and pressure, and thus the interpretation of high conductivity anomalies distributed in representative regional metamorphic belts is still not comprehensive.…”