Late metal-silicate separation on the IAB parent asteroid: Constraints from combined W and Pt isotopes and thermal modelling

The ε182W values obtained for the IAB iron meteorites range from −3.61 ± 0.10 to −2.73 ± 0.09. Correlating εiPt with ε182W data yields a pre-neutron capture ε182W of −2.90 ± 0.06. This corresponds to a metal-silicate separation age of 6.0 ± 0.8 Ma after CAI for the IAB parent body, and is interpreted to represent a body-wide melting event. Later, between 10 and 14 Ma after CAI, an impact led to a catastrophic break-up and subsequent reassembly of the parent body. Thermal models of the interior evolution that are consistent with these estimates suggest that the IAB parent body underwent metal-silicate separation as a result of internal heating by short-lived radionuclides and accreted at around 1.4±0.1 Ma after CAIs with a radius of greater than 60 km.