Radiative Thermal Conductivity of the Lower Mantle Emma

Lower Mantle Thermal Conductivity Mantle QCMB Core Lay et al. , 2008 Better constraints

Heat Conduction Mechanisms • Two mechanisms likely control heat flow in lower mantle thermal

Diffusive Radiative Heat Transfer Thermal boundary layer (105 m) Mantle Scales Grain size (10

$Mantle Index of Refraction Model Anderson and Schreiber, 1965 n = 1. 05 +$

High-Pressure Absorption Coefficient of (Mg, Fe)Si. O 3 Perovskite pressure Goncharov et al. ,

krad(T) of Major Lower Mantle Phases Perovskite Keppler et al. Goncharov et al. P

krad(T) of Major Lower Mantle Phases Perovskite Ferropericlase Keppler et al. 6% Fe 15%

krad vs. Mantle Depth Perovskite (Keppler et al. ) Perovskite (Goncharov et al. )

Composite Mantle krad q Data from Keppler et al. Parallel Data from Goncharov et

Summary • krad at CMB 1 -4 W/m·K • Sensitivity of krad to mantle

$Index of Refraction and Temperature Profiles$

Slides: 17

Download presentation

Radiative Thermal Conductivity of the Lower Mantle Emma Rainey Abby Kavner Laurent Pilon

Lower Mantle Thermal Conductivity Mantle QCMB Core Lay et al. , 2008 Better constraints on kmantle needed

Heat Conduction Mechanisms • Two mechanisms likely control heat flow in lower mantle thermal boundary layer • Relative importance not well-known Lattice Vibrations http: //quantum-sidsen. blogspot. com/ Radiation Courtesy of B. Greenhagen

Diffusive Radiative Heat Transfer Thermal boundary layer (105 m) Mantle Scales Grain size (10 -3 m) Phonon scattering length (10 -9 m) Photon absorption length (10 -4 m) DT across grain < 10 -4 K krad depends on two optical properties: – Index of refraction (nl) – Absorption coefficient (bl)

$Mantle Index of Refraction Model Anderson and Schreiber, 1965 n = 1. 05 +$

Mantle Index of Refraction Model Anderson and Schreiber, 1965 n = 1. 05 + 0. 188 r • Dominant high P/T effect on n expected to be from density • n scales linearly with density for minerals n 1. 8 – 2. 2 in lower mantle Refractive index

High-Pressure Absorption Coefficient of (Mg, Fe)Si. O 3 Perovskite pressure Goncharov et al. , 2008 Keppler et al. , 2008

krad(T) of Major Lower Mantle Phases Perovskite Keppler et al. Goncharov et al. P P

krad(T) of Major Lower Mantle Phases Perovskite Ferropericlase Keppler et al. 6% Fe 15% Fe Goncharov et al. P P P 25% Fe P P (Mg, Fe)O absorption coefficients from Goncharov et al. , 2006 and 2009

krad vs. Mantle Depth Perovskite (Keppler et al. ) Perovskite (Goncharov et al. ) Ferropericlase

Composite Mantle krad q Data from Keppler et al. Parallel Data from Goncharov et al. Series • Composite mantle: 80% Pv + 20% Fp q

Summary • krad at CMB 1 -4 W/m·K • Sensitivity of krad to mantle properties: • Iron content has large effect compared to temperature • Individual phases and phase configuration have significant effect • Calculated krad is upper bound • Neglected scattering and minor impurities

BACKUPS

$Index of Refraction and Temperature Profiles$

Index of Refraction and Temperature Profiles