Potassium isotopic composition of the Moon

摘要: Abstract The Moon is depleted in water and other volatiles compared to Earth the bulk solar composition. Such depletion of volatile elements stable isotope fractionations these can be used better understand origin early differentiation history Moon. In this study, we focus on moderately element, potassium, report K elemental abundances isotopic compositions (δ41K relative NIST SRM 3141a) for nineteen Apollo lunar rocks meteorites (twenty-two subsamples), spanning all major geochemical petrologic types materials. low-Ti high-Ti basalts are indistinguishable, providing a basalt average δ41K –0.07 ± 0.09‰ (2SD), which also consider best estimate mantle silicate significant enrichment its heavier isotopes Moon, with (δ41K = –0.48 ± 0.03‰), consistent previous analyses (e.g., Cl, Cu, Zn, Ga, Rb). We nonmare samples, show large variations ratios basalts. interpret fractionation as result late-stage magma ocean degassing during urKREEP formation, coupled Cl fractionation. Degassing likely triggered redistribution enriching reservoir heavy while implanting light signatures onto surface. This scenario suggests heterogeneous distribution consequence magmatic evolution.