Temperature-dependent thermal diffusivity of the Earth’s crust and implications for magmatism

摘要: The rate of heat transfer by conduction is the dominant factor that determines thermal evolution planetary crust and lithosphere. Most models Earth's assume constant values for diffusivity, owing to large experimental uncertainties in measuring this property rocks at high temperature. Whittington et al. have used recent advances laser-flash analysis on three different crustal types show diffusivity strongly decreases with increasing They find be about half commonly assumed mid-crustal temperatures therefore conclude hot middle lower a much more effective insulator than previously thought. also present lithospheric during continental collision, demonstrate temperature dependence rock properties leads positive feedback between strain heating shear zones efficient insulation, removing requirement unusually radiogenic production achieve melting temperatures. lithosphere governed conduction, which determined rock's usually remain constant. Alan colleagues fact temperature, concluding thought; removes largely conduction1,2,3. governing physical are (κ) conductivity (k = κρCP), where ρ denotes density CP specific capacity pressure. Although both κ k decrease above ambient temperature4,5, most Earth’s (∼1 mm2 s-1) and/or (∼3 5 W m-1 K-1)6,7 associated conventional contact methods Recent analysis8,9 permit accurate (±2 per cent) measurements minerals geologically relevant temperatures10. Here we provide data from types, showing 1.5–2.5 mm2 s-1 conditions, approaching 0.5 mm2 s-1 latter value approximately assumed, Above quartz α–β phase transition, nearly independent similar mantle materials11. Calculated indicate its negative smaller κ, increase but diminishes 50 cent surface transition. We collision Positive heating, increased insulation partial predicted occur many tectonic settings, mantle, facilitating reworking differentiation12.