HR: 0830h
AN: P21D-17    [Abstracts]
TI: Towards a Balanced Power Budget for Earth
AU: * Anderson, O L
EM: ola@ess.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 595 Charles E. Young Dr. E, Los Angeles, CA 90095-1567 United States
AU: * Anderson, O L
EM: ola@ess.ucla.edu
AF: Department of Earth and Space Sciences, UCLA, 595 Charles E. Young Dr. East, Los Angeles, CA 90095-1567 United States
AB: Probable mechanisms that produce or absorb power for Earth and the amount of power they individually produce or absorb are enumerated. Power-producers include radiogenic heat from the core, mantle, and crust; latent heat of crystallization from the growing inner core; gravitational heat from the thermal contraction of Earth due to its cooling; and gravitational heat from the growing crust. Generation of mantle plumes is also taken to be a power producer. The lifetime of the inner core must be consistent with the power produced in the core. I use the preferred model of Nimmo et al. (2004) in which the power produced by the core is augmented by 2.1 terawatts (TW) of potassium-produced radiogenic energy, giving a total power of 7.1~TW flowing from the core to the mantle. The chief difficulty in making the power balance is to find the value of the mantle's radiogenic power. I do this by enumerating the nonradiogenic power of the mantle excluding the lithosphere, but including the power from the core. This enumeration includes power from mantle convection, from mantle plumes, and nonradiogenic power arriving from the core, the sum of which crosses the basal plane boundary of the lithosphere. Since this sum must equal Earth's total heat loss (44.3 TW) less the mantle's radiogenic power, I find the mantle's radiogenic power to be 23.5 ± 1.5~TW. This is lower than mantle radiogenic power estimates from Turcotte and Schubert (2002) and greater than from Stacey (1992). The power budget for the lithosphere and the crust is taken from Turcotte and Schubert (2002), except that it is modified to include the power loss from tidal dissipation (4 TW), which Verhoogen (1980) recommends be taken into account. Expenditures in the lithosphere are tidal dissipation, continental radiogenic heating, basal heating of the lithosphere and subduction of the lithosphere. Within the error limits set by the various mechanisms, the power income of Earth is found to equal its power expenditure and also equal its measured power loss (44.3 TW).
DE: 1507 Core processes (8115)
DE: 3924 High-pressure behavior
DE: 5134 Thermal properties
DE: 5418 Heat flow
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly