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 β spectra. We carefully account for all branches in
K decay using the updated β energy spectrum from physics and an updated branching
ratio from geological studies. 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 K, Rb, Sm, Th, U, and U. Given element
concentrations in kg-element/kg-rock and density ρ in kg/m, a simplied equation
to calculate the heat production in a rock is:
h [μWm] = ρ(3.387 × 10 [K] + 0.01139 [Rb] + 0.04607 [Sm] + 26.18 [Th] + 98.29 [U])
The radiogenic heating rate of earth-like material at Solar System formation was some 10 to 10 times greater than present-day values, largely due to decay of Al in the silicate fraction, which was the dominant radiogenic heat source for the first ~10My. Decay of Fe contributed a non-negligible amount of heating during the first ~15My after CAI (Calcium Aluminum Inclusion) formation, interestingly within the time frame of core{mantle segregation.