A. Yoneda et H. Spetzler, TEMPERATURE-FLUCTUATION AND THERMODYNAMIC PROPERTIES IN EARTHS LOWER MANTLE - AN APPLICATION OF THE COMPLETE TRAVEL-TIME EQUATION OF STATE, Earth and planetary science letters, 126(4), 1994, pp. 369-377
The complete travel time equation of state (CT-EOS) enables us to obta
in all the thermodynamic parameters from travel time or velocity measu
rements of elastic waves at simultaneously high pressure and temperatu
re. Here we formulate the adiabatic CT-EOS and apply it to the lateral
heterogeneity of seismic wave velocity in the lower mantle. We obtain
ed internally consistent results for temperature, thermal expansivity
and the Gruneisen constant in the low mantle; at the depth (2741 km) j
ust above D'' layer, the most likely results are similar to 2500 K for
temperature, similar to 1.0X10(-5) K-1 for thermal expansivity and si
milar to 1.0 for the Gruneisen constant. We also discuss the geophysic
al implication of the small thermal expansivity suggested in the deep
lower mantle.