Elucidation of Asteroidal Crust Evolution Based on U–Pb and Hf–W Dating of Differentiated Meteorites

Abstract

Chronologies of extraterrestrial materials provide key information to reveal the formation and evolution of our planetary system. Uranium–lead dating utilizes the decays of long-lived radionuclides ²³⁸U and ²³⁵U to obtain absolute age information of various geological events of the targets. Hafnium–tungsten dating uses an excess of ¹⁸²W, a daughter nuclide of the short-lived radionuclide ¹⁸²Hf, to determine relative ages of the early solar system events (≥ ～4.5 billion years ago).In-situ measurements by high-spatial resolution secondary ion mass spectrometers (SIMS) enable to determine the U–Pb/²⁰⁷Pb–²⁰⁶Pb ages and ¹⁸²Hf–¹⁸²W ages of accessory minerals (e.g., zircon and Ca-phosphates) contained in various types of meteorites. Here, I summarize the recent chronological works and their possible interpretations focusing on Vesta-related meteorites groups, eucrites and mesosiderites.