Recent advances in high precision mass spectrometry have made it possible to study the early history of the Earth (4- 4.6 Ga ago) using the decay signature of the extinct nuclide 146Sm. 146Sm was present at the beginning of solar system history with an abundance of only 0.25% of Sm. Observable variations in the abundance of its daughter nuclide 142Nd record differentiation processes active only during the first 300 Ma of Earth history. By linking the short-lived 146Sm-142Nd and long-lived 147Sm-143Nd chronometers into a "coupled" systematics, it is possible to precisely constrain the formation history of the Earth's primordial protocrust. The Hadean epoch (4.0-4.6 Ga) is the least well-known period in Earth history. This project will map out a basic chronological outline of global geochemical differentiation.
