Lu-Hf systematics and the early silicate differentiation history of the Moon

Basic data for this project

Description

The Earth's Moon is an invaluable archive for investigating the earliest differentiation history of the Earth and Moon, providing information that is inaccessible from studies on even the oldest terrestrial samples. Combined Lu–Hf and Sm–Nd studies on lunar samples provide key information on the timing and nature of the early differentiation of the Moon, and are essential for distinguishing between a chondritic and non-chondritic composition of the Earth and Moon. For instance, the lunar Hf-Nd isotopic record has been used to argue for non-chondritic relative abundances of refractory lithophile elements in the Earth and Moon. If true, all geochemical models for the differentiation of the Earth need to be revised entirely. However, cosmic-ray induced Hf isotope shifts can significantly bias the Lu-Hf record of lunar samples, a phenomenon that has not been accounted for in previous studies. We aim to (1) evaluate the influence of neutron-capture reactions on the Lu-Hf system in lunar rocks, and (2) to comprehensively assess the Lu–Hf record of all known major silicate reservoirs of the Moon.