Abstrakt
We report the Earth's rate of radiogenic heat production and (anti)neutrino luminosity from geologically relevant short-lived radionuclides (SLR) and long-lived radionuclides (LLR) using decay constants from the geological community, updated nuclear physics parameters, and calculations of the beta spectra. We track the time evolution of the radiogenic power and luminosity of the Earth over the last 4.57 billion years, assuming an absolute abundance for the refractory elements in the silicate Earth and key volatile/refractory element ratios (e.g., Fe/Al, K/U, and Rb/Sr) to set the abundance levels for the moderately volatile elements.
The relevant decays for the present-day heat production in the Earth (19.9 +/- 3.0 TW) are from(40)K,Rb-87,Sm-147,Th-232,U-235, and(238)U. Given element concentrations in kg-element/kg-rock and density rho in kg/m(3), a simplified equation to calculate the present-day heat production in a rock is h[mu W m-(3])=rho 3.387 x 10(-3) K + 0.01139Rb + 0.04595Sm+26.18Th+98.29U) The radiogenic heating rate of Earth-like material at solar system formation was some 10(3) to 10(4) times greater than present-day values, largely due to decay of Al-26 in the silicate fraction, which was the dominant radiogenic heat source for the first similar to 10 Ma.
Assuming instantaneous Earth formation, the upper bound on radiogenic energy supplied by the most powerful short-lived radionuclide Al-26 (t(1/2)= 0.7 Ma) is 5.5x10(31) J, which is comparable (within a factor of a few) to the planet's gravitational binding energy. Plain Language Summary The decay of radioactive elements in planetary interiors produces heat that drives the dynamic processes of convection (core and mantle), melting, and volcanism in rocky bodies in the solar system and beyond.
For elements with half-lives of 100,000 to 100 billion years, uncertainties in their decay constants range from 0.2% to similar to 4%, and comparing data from physics versus geology shows differences of about 1% to 4%. These differences, combined with uncertainties in Q values (energy released in reaction), lead to diverging results for heat production and for predictions of the amount of energy removed from the rocky body by emitted (anti)neutrinos.