TUNGSTEN ISOTOPES AND THE EARLY DEVELOPMENT OF THE EARTH AND MOON

Abstract

The rates of accretion and core formation of the Earth and other inner solar system objects can be effectively studied using the newly developed 182Hf-182W chronometer. This approach offers far more leverage than any other short-lived nuclide system because: 1. the half-life of 9 Myrs is ideal for accretionary timescales; 2. both parent and daughter elements are highly refractory and in known, chondritic proportions in the Earth; 3. the initial 182Hf atomic abundance at the start of the solar system was relatively high; and 4. Hf and W are strongly fractionated by the early processes of melting and core formation.